Provided by: librose-db-object-perl_0.810-1_all 
NAME
Rose::DB::Object::Manager - Fetch multiple Rose::DB::Object-derived objects from the
database using complex queries.
SYNOPSIS
##
## Given the following Rose::DB::Object-derived classes...
##
package Category;
use base 'Rose::DB::Object';
__PACKAGE__->meta->setup
(
table => 'categories',
columns =>
[
id => { type => 'int', primary_key => 1 },
name => { type => 'varchar', length => 255 },
description => { type => 'text' },
],
unique_key => 'name',
);
...
package CodeName;
use base 'Rose::DB::Object';
__PACKAGE__->meta->setup
(
table => 'code_names',
columns =>
[
id => { type => 'int', primary_key => 1 },
product_id => { type => 'int' },
name => { type => 'varchar', length => 255 },
applied => { type => 'date', not_null => 1 },
],
foreign_keys =>
[
product =>
{
class => 'Product',
key_columns => { product_id => 'id' },
},
],
);
...
package Product;
use base 'Rose::DB::Object';
__PACKAGE__->meta->setup
(
table => 'products',
columns =>
[
id => { type => 'int', primary_key => 1 },
name => { type => 'varchar', length => 255 },
description => { type => 'text' },
category_id => { type => 'int' },
region_num => { type => 'int' },
status =>
{
type => 'varchar',
check_in => [ 'active', 'inactive' ],
default => 'inactive',
},
start_date => { type => 'datetime' },
end_date => { type => 'datetime' },
date_created => { type => 'timestamp', default => 'now' },
last_modified => { type => 'timestamp', default => 'now' },
],
unique_key => 'name',
foreign_keys =>
[
category =>
{
class => 'Category',
key_columns =>
{
category_id => 'id',
}
},
],
relationships =>
[
code_names =>
{
type => 'one to many',
class => 'CodeName',
column_map => { id => 'product_id' },
manager_args =>
{
sort_by => CodeName->meta->table . '.applied DESC',
},
},
],
);
...
##
## Create a manager class
##
package Product::Manager;
use base 'Rose::DB::Object::Manager';
sub object_class { 'Product' }
__PACKAGE__->make_manager_methods('products');
# The call above creates the methods shown below. (The actual
# method bodies vary slightly, but this is the gist of it...)
#
# sub get_products
# {
# shift->get_objects(@_, object_class => 'Product');
# }
#
# sub get_products_iterator
# {
# shift->get_objects_iterator(@_, object_class => 'Product');
# }
#
# sub get_products_count
# {
# shift->get_objects_count(@_, object_class => 'Product');
# }
#
# sub update_products
# {
# shift->update_objects(@_, object_class => 'Product');
# }
#
# sub delete_products
# {
# shift->delete_objects(@_, object_class => 'Product');
# }
...
##
## Use the manager class
##
#
# Get a reference to an array of objects
#
$products =
Product::Manager->get_products
(
query =>
[
category_id => [ 5, 7, 22 ],
status => 'active',
start_date => { lt => '15/12/2005 6:30 p.m.' },
name => { like => [ '%foo%', '%bar%' ] },
],
sort_by => 'category_id, start_date DESC',
limit => 100,
offset => 80,
);
foreach my $product (@$products)
{
print $product->id, ' ', $product->name, "\n";
}
#
# Get objects iterator
#
$iterator =
Product::Manager->get_products_iterator
(
query =>
[
category_id => [ 5, 7, 22 ],
status => 'active',
start_date => { lt => '15/12/2005 6:30 p.m.' },
name => { like => [ '%foo%', '%bar%' ] },
],
sort_by => 'category_id, start_date DESC',
limit => 100,
offset => 80,
);
while($product = $iterator->next)
{
print $product->id, ' ', $product->name, "\n";
}
print $iterator->total;
#
# Get objects count
#
$count =
Product::Manager->get_products_count
(
query =>
[
category_id => [ 5, 7, 22 ],
status => 'active',
start_date => { lt => '15/12/2005 6:30 p.m.' },
name => { like => [ '%foo%', '%bar%' ] },
],
);
die Product::Manager->error unless(defined $count);
print $count; # or Product::Manager->total()
#
# Get objects and sub-objects in a single query
#
$products =
Product::Manager->get_products
(
with_objects => [ 'category', 'code_names' ],
query =>
[
category_id => [ 5, 7, 22 ],
status => 'active',
start_date => { lt => '15/12/2005 6:30 p.m.' },
# We need to disambiguate the "name" column below since it
# appears in more than one table referenced by this query.
# When more than one table is queried, the tables have numbered
# aliases starting from the "main" table ("products"). The
# "products" table is t1, "categories" is t2, and "code_names"
# is t3. You can read more about automatic table aliasing in
# the documentation for the get_objects() method below.
#
# "category.name" and "categories.name" would work too, since
# table and relationship names are also valid prefixes.
't2.name' => { like => [ '%foo%', '%bar%' ] },
],
sort_by => 'category_id, start_date DESC',
limit => 100,
offset => 80,
);
foreach my $product (@$products)
{
# The call to $product->category does not hit the database
print $product->name, ': ', $product->category->name, "\n";
# The call to $product->code_names does not hit the database
foreach my $code_name ($product->code_names)
{
# This call doesn't hit the database either
print $code_name->name, "\n";
}
}
#
# Update objects
#
$num_rows_updated =
Product::Manager->update_products(
set =>
{
end_date => DateTime->now,
region_num => { sql => 'region_num * -1' }
status => 'defunct',
},
where =>
[
start_date => { lt => '1/1/1980' },
status => [ 'active', 'pending' ],
]);
#
# Delete objects
#
$num_rows_deleted =
Product::Manager->delete_products(
where =>
[
status => [ 'stale', 'old' ],
name => { like => 'Wax%' },
or =>
[
start_date => { gt => '2008-12-30' },
end_date => { gt => 'now' },
],
]);
DESCRIPTION
Rose::DB::Object::Manager is a base class for classes that select rows from tables fronted
by Rose::DB::Object-derived classes. Each row in the table(s) queried is converted into
the equivalent Rose::DB::Object-derived object.
Class methods are provided for fetching objects all at once, one at a time through the use
of an iterator, or just getting the object count. Subclasses are expected to create
syntactically pleasing wrappers for Rose::DB::Object::Manager class methods, either
manually or with the make_manager_methods method. A very minimal example is shown in the
synopsis above.
CLASS METHODS
dbi_prepare_cached [BOOL]
Get or set a boolean value that indicates whether or not this class will use DBI's
prepare_cached method by default (instead of the prepare method) when preparing SQL
queries. The default value is false.
default_limit_with_subselect [BOOL]
Get or set a boolean value that determines whether or not this class will consider
using a sub-query to express "limit"/"offset" constraints when fetching sub-objects
related through one of the "...-to-many" relationship types. Not all databases
support this syntax, and not all queries can use it even in supported databases. If
this parameter is true, the feature will be used when possible, by default. The
default value is true.
default_manager_method_types [ LIST | ARRAYREF ]
Get or set the default list of method types used by the make_manager_methods method.
The default list is "objects", "iterator", "count", "delete", and "update".
default_nested_joins [BOOL]
Get or set a boolean value that determines whether or not this class will consider
using nested JOIN syntax when fetching related objects. Not all databases support
this syntax, and not all queries can use it even in supported databases. If this
parameter is true, the feature will be used when possible, by default. The default
value is true.
default_objects_per_page [NUM]
Get or set the default number of items per page, as returned by the get_objects method
when used with the "page" and/or "per_page" parameters. The default value is 20.
delete_objects [ PARAMS | ARRAYREF | HASHREF ]
Delete rows from a table fronted by a Rose::DB::Object-derived class based on PARAMS,
where PARAMS are name/value pairs. Returns the number of rows deleted, or undef if
there was an error.
If the first argument is a reference to a hash or array, it is converted to a
reference to an array (if necessary) and taken as the value of the "where" parameter.
Valid parameters are:
all BOOL
If set to a true value, this parameter indicates an explicit request to delete all
rows from the table. If both the "all" and the "where" parameters are passed, a
fatal error will occur.
db DB
A Rose::DB-derived object used to access the database. If omitted, one will be
created by calling the init_db method of the object_class.
prepare_cached BOOL
If true, then DBI's prepare_cached method will be used (instead of the prepare
method) when preparing the SQL statement that will delete the objects. If
omitted, the default value is determined by the dbi_prepare_cached class method.
object_class CLASS
The name of the Rose::DB::Object-derived class that fronts the table from which
rows are to be deleted. This parameter is required; a fatal error will occur if
it is omitted. Defaults to the value returned by the object_class class method.
where ARRAYREF
The query parameters, passed as a reference to an array of name/value pairs.
These pairs are used to formulate the "where" clause of the SQL query that is used
to delete the rows from the table. Arbitrarily nested boolean logic is supported.
For the complete list of valid parameter names and values, see the documentation
for the "query" parameter of the build_select function in the
Rose::DB::Object::QueryBuilder module.
If this parameter is omitted, this method will refuse to delete all rows from the
table and a fatal error will occur. To delete all rows from a table, you must
pass the "all" parameter with a true value. If both the "all" and the "where"
parameters are passed, a fatal error will occur.
error
Returns the text message associated with the last error, or false if there was no
error.
error_mode [MODE]
Get or set the error mode for this class. The error mode determines what happens when
a method of this class encounters an error. The default setting is "fatal", which
means that methods will croak if they encounter an error.
PLEASE NOTE: The error return values described in the method documentation in the rest
of this document are only relevant when the error mode is set to something "non-
fatal." In other words, if an error occurs, you'll never see any of those return
values if the selected error mode dies or croaks or otherwise throws an exception when
an error occurs.
Valid values of MODE are:
carp
Call Carp::carp with the value of the object error as an argument.
cluck
Call Carp::cluck with the value of the object error as an argument.
confess
Call Carp::confess with the value of the object error as an argument.
croak
Call Carp::croak with the value of the object error as an argument.
fatal
An alias for the "croak" mode.
return
Return a value that indicates that an error has occurred, as described in the
documentation for each method.
In all cases, the class's "error" attribute will also contain the error message.
get_objects [ PARAMS | HASHREF | ARRAYREF ]
Get Rose::DB::Object-derived objects based on PARAMS, where PARAMS are name/value
pairs. Returns a reference to a (possibly empty) array, or undef if there was an
error.
If the first argument is a reference to a hash or array, it is converted to a
reference to an array (if necessary) and taken as the value of the "query" parameter.
Each table that participates in the query will be aliased. Each alias is in the form
"tN" where "N" is an ascending number starting with 1. The tables are numbered as
follows.
• The primary table is always "t1"
• The table(s) that correspond to each relationship or foreign key named in the
"with_objects" parameter are numbered in order, starting with "t2"
• The table(s) that correspond to each relationship or foreign key named in the
"require_objects" parameter are numbered in order, starting where the
"with_objects" table aliases left off.
"Many to many" relationships have two corresponding tables, and therefore will use two
"tN" numbers. All other supported of relationship types only have just one table and
will therefore use a single "tN" number.
For example, imagine that the "Product" class shown in the synopsis also has a "many
to many" relationship named "colors." Now consider this call:
$products =
Product::Manager->get_products(
require_objects => [ 'category' ],
with_objects => [ 'code_names', 'colors' ],
multi_many_ok => 1,
query => [ status => 'defunct' ],
sort_by => 't1.name');
The "products" table is "t1" since it's the primary table--the table behind the
"Product" class that "Product::Manager" manages. Next, the "with_objects" tables are
aliased. The "code_names" table is "t2". Since "colors" is a "many to many"
relationship, it gets two numbers: "t3" and "t4". Finally, the "require_objects"
tables are numbered: the table behind the foreign key "category" is "t5". Here's an
annotated version of the example above:
# Table aliases in the comments
$products =
Product::Manager->get_products(
# t5
require_objects => [ 'category' ],
# t2 t3, t4
with_objects => [ 'code_names', 'colors' ],
multi_many_ok => 1,
query => [ status => 'defunct' ],
sort_by => 't1.name'); # "products" is "t1"
Also note that the "multi_many_ok" parameter was used in order to suppress the warning
that occurs when more than one "... to many" relationship is included in the
combination of "require_objects" and "with_objects" ("code_names" (one to many) and
"colors" (many to many) in this case). See the documentation for "multi_many_ok"
below.
The "tN" table aliases are for convenience, and to isolate end-user code from the
actual table names. Ideally, the actual table names should only exist in one place in
the entire code base: in the class definitions for each Rose::DB::OBject-derived
class.
That said, when using Rose::DB::Object::Manager, the actual table names can be used as
well. But be aware that some databases don't like a mix of table aliases and real
table names in some kinds of queries.
Valid parameters to get_objects are:
allow_empty_lists BOOL
If set to true, "query" parameters with empty lists as values are allowed. For
example:
@ids = (); # empty list
Product::Manager->get_products(
query =>
[
id => \@ids,
...
]);
By default, passing an empty list as a value will cause a fatal error.
db DB
A Rose::DB-derived object used to access the database. If omitted, one will be
created by calling the init_db method of the "object_class".
debug BOOL
If true, print the generated SQL to STDERR.
distinct [ BOOL | ARRAYREF ]
If set to any kind of true value, then the "DISTINCT" SQL keyword will be added to
the "SELECT" statement. Specific values trigger the behaviors described below.
If set to a simple scalar value that is true, then only the columns in the primary
table ("t1") are fetched from the database.
If set to a reference to an array of table names, "tN" table aliases, or
relationship or foreign key names, then only the columns from the corresponding
tables will be fetched. In the case of relationships that involve more than one
table, only the "most distant" table is considered. (e.g., The map table is
ignored in a "many to many" relationship.) Columns from the primary table ("t1")
are always selected, regardless of whether or not it appears in the list.
This parameter conflicts with the "fetch_only" parameter in the case where both
provide a list of table names or aliases. In this case, if the value of the
"distinct" parameter is also reference to an array table names or aliases, then a
fatal error will occur.
fetch_only ARRAYREF
ARRAYREF should be a reference to an array of table names or "tN" table aliases.
Only the columns from the corresponding tables will be fetched. In the case of
relationships that involve more than one table, only the "most distant" table is
considered. (e.g., The map table is ignored in a "many to many" relationship.)
Columns from the primary table ("t1") are always selected, regardless of whether
or not it appears in the list.
This parameter conflicts with the "distinct" parameter in the case where both
provide a list of table names or aliases. In this case, then a fatal error will
occur.
for_update BOOL
If true, this parameter is translated to be the equivalent of passing the lock
parameter and setting the "type" to "for update". For example, this:
for_update => 1
is equivalent to this:
lock => { type => 'for update' }
See the lock parameter below for more information.
hints HASHREF
A reference to a hash of hints that influence the SQL generated to fetch the
objects. Hints are just "suggestions" and may be ignored, depending on the actual
features of the database being queried. Use the debug parameter to see the
generated SQL. Most of the current hints apply to MySQL only. See the relevant
documentation for more details:
<http://dev.mysql.com/doc/refman/5.0/en/select.html>
The hints hash is keyed by tN table aliases or relationship names. The value of
each key is a reference to a hash of hint directives. In the absence of any key
for "t1" or the name of the primary table, the entire hints hash is considered
applicable to the primary table.
Valid hint directives are:
all_rows BOOL
If true, direct the database to choose the query plan that returns all the
records as quickly as possible.
big_result BOOL
If true, indicate to the database that the result set is expected to be big.
buffer_result BOOL
If true, force the result to be put into a temporary table.
cache BOOL
If true, ask the database to store the result in its query cache.
calc_found_rows BOOL
If true, ask the database to internally calculate the number of rows found,
ignoring any limit or offset arguments.
comment TEXT
Add a comment after the "SELECT" keyword in the query. TEXT should not be
surrounded by any comment delimiters. The appropriate delimiters will be
added automatically.
first_rows BOOL
If true, direct the database to choose the query plan that returns the first
result record as soon as possible.
force_index [ INDEX | ARRAYREF ]
Force the use of the named indexes, specified by an index name or a reference
to an array of index names.
high_priority BOOL
If true, give this query higher priority.
ignore_index [ INDEX | ARRAYREF ]
Ignore the named indexes, specified by an index name or a reference to an
array of index names.
no_cache BOOL
If true, ask the database not to store the result in its query cache.
small_result BOOL
If true, indicate to the database that the result set is expected to be small.
straight_join BOOL
If true, ask the database to join the tables in the order that they are listed
in the "FROM" clause of the SQL statement.
strict_ops BOOL
If true, any comparison operator used in the "query" that is not listed in the
Rose::DB::Object::QueryBuilder documentation will cause a fatal error. The
default value is determined by the strict_ops class method.
use_index [ INDEX | ARRAYREF ]
Prefer to use the named indexes, specified by an index name or a reference to
an array of index names.
inject_results BOOL
If true, then the data returned from the database will be directly "injected" into
the objects returned by this method, bypassing the constructor and column mutator
methods for each object class. The default is false. This parameter is ignored
(i.e., treated as if it were false) if the "select" parameter is passed.
This parameter is useful for situations where the performance of get_objects is
limited by the speed at which Rose::DB::Object-derived objects can be created.
It's safe to set this parameter to true only if the constructor and column mutator
methods for all of the classes involved do not have any side-effects (or if it's
is okay to bypass any side-effects).
The default Rose::DB::Object constructor and the column mutator methods created by
the column classes included in the Rose::DB::Object module distribution do not
have any side-effects and should therefore be safe to use with this parameter.
limit NUM
Return a maximum of NUM objects.
limit_with_subselect BOOL
This parameter controls whether or not this method will consider using a sub-query
to express "limit"/"offset" constraints when fetching sub-objects related through
one of the "...-to-many" relationship types. Not all databases support this
syntax, and not all queries can use it even in supported databases. If this
parameter is true, the feature will be used when possible.
The default value is determined by the default_limit_with_subselect class method.
lock [ TYPE | HASHREF ]
Select the objects using some form of locking. These lock directives have
database-specific behavior and not all directives are supported by all databases.
Consult your database's documentation to find out more. Use the debug parameter
to see the generated SQL.
The value should be a reference to a hash or a TYPE string, which is equivalent to
setting the value of the "type" key in the hash reference form. For example,
these are both equivalent:
lock => 'for update'
lock => { type => 'for update' }
Valid hash keys are:
columns ARRAYREF
A reference to an array of column names to lock. The columns may be prefixed
with their table name or their "tN" alias (e.g., "mytable.mycol" or
"t2.mycol") or left unadorned if they are not ambiguous. References to
scalars will be de-referenced and used as-is, included literally in the SQL
locking clause.
nowait BOOL
If true, do not wait to acquire the lock. If supported, this is usually by
adding a "NOWAIT" directive to the SQL.
on ARRAYREF
A reference to an array of items to lock. Depending on the database, these
may be column or tables. Both column and table names should be specified
using dot-separated relationship paths.
For example, "vendor.region.name" would lock the "name" column in the table
arrived at by traversing the "vendor" and then the "region" relationships,
starting from the primary table ("t1"). Lone column names may also be used,
provided they're not ambiguous.
For locking whole tables, "vendor.region" would lock the table arrived at by
traversing the "vendor" and then the "region" relationships. (See the
require_objects parameter for more information on relationship traversal.)
Finally, references to scalars will be de-referenced and used as-is, included
literally in the SQL locking clause.
skip_locked BOOL
If true, skip any locked rows. If supported, this is usually by adding a
"SKIP LOCKED" clause to the SQL.
tables ARRAYREF
A reference to an array of tables to lock. Table named or "tN" aliases may be
used. References to scalars will be de-referenced and used as-is, included
literally in the SQL locking clause.
type TYPE
The type of lock to acquire. Valid values for TYPE are "for update" and
"shared". This hash key is required unless the for_update parameter was
passed with a true value.
wait TIME
Wait for the specified TIME (generally seconds) before giving up acquiring the
lock. If supported, this is usually by adding a "WAIT ..." clause to the SQL.
You may pass only one of the parameters that specifies "what to lock" (i.e.,
"columns", "on", or "tables").
nested_joins BOOL
This parameter controls whether or not this method will consider using nested JOIN
syntax when fetching related objects. Not all databases support this syntax, and
not all queries will use it even in supported databases. If this parameter is
true, the feature will be used when possible.
The default value is determined by the default_nested_joins class method.
multi_many_ok BOOL
If true, do not print a warning when attempting to do multiple LEFT OUTER JOINs
against tables related by "... to many" relationships. See the documentation for
the "with_objects" parameter for more information.
nonlazy [ BOOL | ARRAYREF ]
By default, get_objects will honor all load-on-demand columns when fetching
objects. Use this parameter to override that behavior and select all columns
instead.
If the value is a true boolean value (typically "1"), then all columns will be
fetched for all participating classes (i.e., the main object class as well as any
sub-object classes).
The value can also be a reference to an array of relationship names. The sub-
objects corresponding to each relationship name will have all their columns
selected. To refer to the main class (the "t1" table), use the special name
"self".
object_args HASHREF
A reference to a hash of name/value pairs to be passed to the constructor of each
"object_class" object fetched, in addition to the values from the database.
object_class CLASS
The name of the Rose::DB::Object-derived objects to be fetched. This parameter is
required; a fatal error will occur if it is omitted. Defaults to the value
returned by the object_class class method.
offset NUM
Skip the first NUM rows. If the database supports some sort of "limit with
offset" syntax (e.g., "LIMIT 10 OFFSET 20") then it will be used. Otherwise, the
first NUM rows will be fetched and then discarded.
This parameter can only be used along with the "limit" parameter, otherwise a
fatal error will occur.
page NUM
Show page number NUM of objects. Pages are numbered starting from 1. A page
number less than or equal to zero causes the page number to default to 1.
The number of objects per page can be set by the "per_page" parameter. If the
"per_page" parameter is supplied and this parameter is omitted, it defaults to 1
(the first page).
If this parameter is included along with either of the "limit" or <offset>
parameters, a fatal error will occur.
per_page NUM
The number of objects per "page". Defaults to the value returned by the
default_objects_per_page class method (20, by default).
If this parameter is included along with either of the "limit" or <offset>
parameters, a fatal error will occur.
prepare_cached BOOL
If true, then DBI's prepare_cached method will be used (instead of the prepare
method) when preparing the SQL statement that will fetch the objects. If omitted,
the default value is determined by the dbi_prepare_cached class method.
query ARRAYREF
The query parameters, passed as a reference to an array of name/value pairs.
These pairs are used to formulate the "where" clause of the SQL query that, in
turn, is used to fetch the objects from the database. Arbitrarily nested boolean
logic is supported.
For the complete list of valid parameter names and values, see the documentation
for the "query" parameter of the build_select function in the
Rose::DB::Object::QueryBuilder module.
This class also supports an extension to the query syntax supported by
Rose::DB::Object::QueryBuilder. In addition to table names and aliases, column
(or column method) names may be prefixed with foreign key or relationship names.
These names may be chained, with dots (".") separating the components.
For example, imagine three tables, "products", "vendors", and "regions", fronted
by three Rose::DB::Object-derived classes, "Product", "Vendor", and "Region",
respectively. Each "Product" has a "Vendor", and each "Vendor" has a "Region".
To select only products whose vendors are in the United States, use a query
argument like this:
query => [ 'vendor.region.name' => 'US' ],
This assumes that the "Product" class has a relationship or foreign key named
"vendor" that points to the product's "Vendor", and that the "Vendor" class has a
foreign key or relationship named "region" that points to the vendor's "Region",
and that 'vendor.region' (or any foreign key or relationship name chain that
begins with 'vendor.region.') is an argument to the "with_objects" or
"require_objects" parameters.
Please note that the "tN" table aliases are not allowed in front of these kinds of
chained relationship parameters. (The chain of relationship names specifies the
target table, so any "tN" alias would be redundant at best, or present a conflict
at worst.)
require_objects ARRAYREF
Only fetch rows from the primary table that have all of the associated sub-objects
listed in ARRAYREF, a reference to an array of foreign key or relationship names
defined for "object_class". The supported relationship types are "one to one,"
"one to many," and "many to many".
For each foreign key or relationship name listed in ARRAYREF, another table will
be added to the query via an implicit inner join. The join conditions will be
constructed automatically based on the foreign key or relationship definitions.
Note that each related table must have a Rose::DB::Object-derived class fronting
it.
Foreign key and relationship names may be chained, with dots (".") separating each
name. For example, imagine three tables, "products", "vendors", and "regions",
fronted by three Rose::DB::Object-derived classes, "Product", "Vendor", and
"Region", respectively. Each "Product" has a "Vendor", and each "Vendor" has a
"Region".
To fetch "Product"s along with their "Vendor"s, and their vendors' "Region"s,
provide a "with_objects" argument like this:
require_objects => [ 'vendor.region' ],
This assumes that the "Product" class has a relationship or foreign key named
"vendor" that points to the product's "Vendor", and that the "Vendor" class has a
foreign key or relationship named "region" that points to the vendor's "Region".
This chaining syntax can be used to traverse relationships of any kind, including
"one to many" and "many to many" relationships, to an arbitrary depth.
The following optional suffixes may be added after any name in the chain in order
to override the join type used:
Suffix Join Type
------ ----------
! Inner join
? Left outer join
Each link in a "require_objects" chain uses an inner join by default. In other
words, the following "require_objects" parameters are all equivalent:
# These all mean the same thing
require_objects => [ 'vendor.region' ]
require_objects => [ 'vendor!.region!' ]
require_objects => [ 'vendor.region!' ]
require_objects => [ 'vendor!.region' ]
Thus, it is only really useful to use the "?" suffix in "require_objects"
parameters (though the "!" suffixes don't do any harm). Here's a useful example
of a call with hybrid join chain:
$products =
Product::Manager->get_products(
require_objects => [ 'vendor.region?' ]);
All product objects returned would have associated vendor objects, but those
vendor objects may or may not have associated region objects.
Note that inner joins may be implicit and nested_joins may or may not be used.
When in doubt, use the debug parameter to see the generated SQL.
Warning: there may be a geometric explosion of redundant data returned by the
database if you include more than one "... to many" relationship in ARRAYREF.
Sometimes this may still be more efficient than making additional queries to fetch
these sub-objects, but that all depends on the actual data. A warning will be
emitted (via Carp::cluck) if you include more than one "... to many" relationship
in ARRAYREF. If you're sure you know what you're doing, you can silence this
warning by passing the "multi_many_ok" parameter with a true value.
Note: the "require_objects" list currently cannot be used to simultaneously fetch
two objects that both front the same database table, but are of different classes.
One workaround is to make one class use a synonym or alias for one of the tables.
Another option is to make one table a trivial view of the other. The objective is
to get the table names to be different for each different class (even if it's just
a matter of letter case, if your database is not case-sensitive when it comes to
table names).
select [ CLAUSE | ARRAYREF ]
Select only the columns specified in either a comma-separated string of column
names or a reference to an array of column names. Strings are naively split
between each comma. If you need more complex parsing, please use the array-
reference argument format instead.
Column names should be prefixed by the appropriate "tN" table alias, the table
name, or the foreign key or relationship name. The prefix should be joined to the
column name with a dot ("."). Examples: "t2.name", "vendors.age".
Unprefixed columns are assumed to belong to the primary table ("t1") and are
explicitly prefixed as such when selecting from more than one table. If a column
name matches "/ AS \w+$/" then no prefix is applied.
If the column name is "*" (e.g., "t1.*") then all columns from that table are
selected.
If an item in the referenced array is itself a reference to a scalar, then that
item will be dereferenced and passed through unmodified.
If selecting sub-objects via the "with_objects" or "require_objects" parameters,
you must select the primary key columns from each sub-object table. Failure to do
so will cause those sub-objects not to be created.
Be warned that you should provide some way to determine which column or method and
which class an item belongs to: a tN prefix, a column name, or at the very least
an "... AS ..." alias clause.
If any "with_objects" or "require_objects" arguments are included in this call,
the "select" list must include at least the primary key column(s) from each table
that contributes to the named relationships.
This parameter conflicts with the "fetch_only" parameter. A fatal error will
occur if both are used in the same call.
If this parameter is omitted, then all columns from all participating tables are
selected (optionally modified by the "nonlazy" parameter).
share_db BOOL
If true, "db" will be passed to each Rose::DB::Object-derived object when it is
constructed. Defaults to true.
sort_by [ CLAUSE | ARRAYREF ]
A fully formed SQL "ORDER BY ..." clause, sans the words "ORDER BY", or a
reference to an array of strings or scalar references to be de-referenced as
needed, joined with a comma, and appended to the "ORDER BY" clause.
If an argument is a reference to a scalar, then it is passed through to the ORDER
BY clause unmodified.
Otherwise, within each string, any instance of "NAME." will be replaced with the
appropriate "tN." table alias, where NAME is a table, foreign key, or relationship
name. All unprefixed simple column names are assumed to belong to the primary
table ("t1").
If selecting sub-objects (via "require_objects" or "with_objects") that are
related through "one to many" or "many to many" relationships, the first condition
in the sort order clause must be a column in the primary table (t1). If this
condition is not met, the list of primary key columns will be added to the
beginning of the sort order clause automatically.
table_aliases BOOL
When only a single table is used in q auery, this parameter controls whether or
not the "tN" aliases are used. If the parameter is not passed, then tables are
aliased. If it is passed with a false value, then tables are not aliased. When
more than one table participates in a query, the "tN" table aliases are always
used and this option is ignored.
unique_aliases BOOL
If true, and if there is no explicit value for the "select" parameter and more
than one table is participating in the query, then each selected column will be
given a unique alias by prefixing it with its table alias and an underscore. The
default value is false. Example:
SELECT
t1.id AS t1_id,
t1.name AS t1_name,
t2.id AS t2_id,
t2.name AS t2_name
FROM
foo AS t1,
bar AS t2
WHERE
...
These unique aliases provide a technique of last resort for unambiguously
addressing a column in a query clause.
where ARRAYREF
This is an alias for the "query" parameter (see above).
with_map_records [ BOOL | METHOD | HASHREF ]
When fetching related objects through a "many to many" relationship, objects of
the map class are not retrieved by default. Use this parameter to override the
default behavior.
If the value is "1", then each object fetched through a mapping table will have
its associated map record available through a "map_record()" attribute.
If a method name is provided instead, then each object fetched through a mapping
table will have its associated map record available through a method of that name.
If the value is a reference to a hash, then the keys of the hash should be "many
to many" relationship names, and the values should be the method names through
which the maps records will be available for each relationship.
with_objects ARRAYREF
Also fetch sub-objects (if any) associated with rows in the primary table based on
a reference to an array of foreign key or relationship names defined for
"object_class". The supported relationship types are "one to one," "one to many,"
and "many to many".
For each foreign key or relationship name listed in ARRAYREF, another table will
be added to the query via an explicit LEFT OUTER JOIN. (Foreign keys whose
columns are all NOT NULL are the exception, however. They are always fetched via
inner joins.) The join conditions will be constructed automatically based on the
foreign key or relationship definitions. Note that each related table must have a
Rose::DB::Object-derived class fronting it. See the synopsis for an example.
"Many to many" relationships are a special case. They will add two tables to the
query (the "map" table plus the table with the actual data), which will offset the
"tN" table numbering by one extra table.
Foreign key and relationship names may be chained, with dots (".") separating each
name. For example, imagine three tables, "products", "vendors", and "regions",
fronted by three Rose::DB::Object-derived classes, "Product", "Vendor", and
"Region", respectively. Each "Product" has a "Vendor", and each "Vendor" has a
"Region".
To fetch "Product"s along with their "Vendor"s, and their vendors' "Region"s,
provide a "with_objects" argument like this:
with_objects => [ 'vendor.region' ],
This assumes that the "Product" class has a relationship or foreign key named
"vendor" that points to the product's "Vendor", and that the "Vendor" class has a
foreign key or relationship named "region" that points to the vendor's "Region".
This chaining syntax can be used to traverse relationships of any kind, including
"one to many" and "many to many" relationships, to an arbitrary depth.
The following optional suffixes may be added after any name in the chain in order
to override the join type used:
Suffix Join Type
------ ----------
! Inner join
? Left outer join
Each link in a "with_objects" chain uses a left outer join by default. In other
words, the following "with_objects" parameters are all equivalent:
# These all mean the same thing
with_objects => [ 'vendor.region' ]
with_objects => [ 'vendor?.region?' ]
with_objects => [ 'vendor.region?' ]
with_objects => [ 'vendor?.region' ]
Thus, it is only really useful to use the "!" suffix in "with_objects" parameters
(though the "?" suffixes don't do any harm). Here's a useful example of a call
with hybrid join chain:
$products =
Product::Manager->get_products(
with_objects => [ 'vendor!.region' ]);
All product objects returned would have associated vendor objects, but those
vendor object may or may not have associated region objects.
Note that inner joins may be implicit and nested_joins may or may not be used.
When in doubt, use the debug parameter to see the generated SQL.
Warning: there may be a geometric explosion of redundant data returned by the
database if you include more than one "... to many" relationship in ARRAYREF.
Sometimes this may still be more efficient than making additional queries to fetch
these sub-objects, but that all depends on the actual data. A warning will be
emitted (via Carp::cluck) if you include more than one "... to many" relationship
in ARRAYREF. If you're sure you know what you're doing, you can silence this
warning by passing the "multi_many_ok" parameter with a true value.
Note: the "with_objects" list currently cannot be used to simultaneously fetch two
objects that both front the same database table, but are of different classes.
One workaround is to make one class use a synonym or alias for one of the tables.
Another option is to make one table a trivial view of the other. The objective is
to get the table names to be different for each different class (even if it's just
a matter of letter case, if your database is not case-sensitive when it comes to
table names).
get_objects_count [PARAMS]
Accepts the same arguments as get_objects, but just returns the number of objects that
would have been fetched, or undef if there was an error.
get_objects_from_sql [ SQL | PARAMS ]
Fetch objects using a custom SQL query. Pass either a single SQL query string or
name/value parameters as arguments. Valid parameters are:
args ARRAYREF
A reference to an array of arguments to be passed to DBI's execute method when the
query is run. The number of items in this array must exactly match the number of
placeholders in the SQL query.
db DB
A Rose::DB-derived object used to access the database. If omitted, one will be
created by calling the init_db method of the "object_class".
object_class CLASS
The class name of the Rose::DB::Object-derived objects to be fetched. Defaults to
the value returned by the object_class class method.
prepare_cached BOOL
If true, then DBI's prepare_cached method will be used (instead of the prepare
method) when preparing the SQL statement that will fetch the objects. If omitted,
the default value is determined by the dbi_prepare_cached class method.
share_db BOOL
If true, "db" will be passed to each Rose::DB::Object-derived object when it is
constructed. Defaults to true.
sql SQL
The SQL query string. This parameter is required.
Each column returned by the SQL query must be either a column or method name in
"object_class". Column names take precedence in the case of a conflict.
Returns a reference to an array of "object_class" objects.
Examples:
package Product::Manager;
use Product;
use base 'Rose::DB::Object::Manager';
sub object_class { 'Product' }
...
$products = Product::Manager->get_objects_from_sql(<<"EOF");
SELECT * FROM products WHERE sku % 2 != 0 ORDER BY status, type
EOF
$products =
Product::Manager->get_objects_from_sql(
args => [ '2005-01-01' ],
sql => 'SELECT * FROM products WHERE release_date > ?');
get_objects_iterator [PARAMS]
Accepts any valid get_objects arguments, but return a Rose::DB::Object::Iterator
object, or undef if there was an error.
get_objects_iterator_from_sql [PARAMS]
Accepts any valid get_objects_from_sql arguments, but return a
Rose::DB::Object::Iterator object, or undef if there was an error.
get_objects_sql [PARAMS]
Accepts the same arguments as get_objects, but return the SQL query string that would
have been used to fetch the objects (in scalar context), or the SQL query string and a
reference to an array of bind values (in list context).
make_manager_methods PARAMS
Create convenience wrappers for Rose::DB::Object::Manager's get_objects,
get_objects_iterator, and get_objects_count class methods in the target class. These
wrapper methods will not overwrite any existing methods in the target class. If there
is an existing method with the same name, a fatal error will occur.
PARAMS can take several forms, depending on the calling context. For a call to
make_manager_methods to succeed, the following information must be determined:
• object class
The class of the Rose::DB::Object-derived objects to be fetched or counted.
• base name or method name
The base name is a string used as the basis of the method names. For example, the
base name "products" might be used to create methods named "get_products",
"get_products_count", "get_products_iterator", "delete_products", and
"update_products".
In the absence of a base name, an explicit method name may be provided instead.
The method name will be used as is.
• method types
The types of methods that should be generated. Each method type is a wrapper for
a Rose::DB::Object::Manager class method. The mapping of method type names to
actual Rose::DB::Object::Manager class methods defaults to the following:
Type Method
-------- ----------------------
objects get_objects()
iterator get_objects_iterator()
count get_objects_count()
delete delete_objects()
update update_objects()
You may override the auto_manager_method_name method in the object_class's
convention manager class to customize one or more of these names.
• target class
The class that the methods should be installed in.
Here are all of the different ways that each of those pieces of information can be
provided, either implicitly or explicitly as part of PARAMS.
• object class
If an "object_class" parameter is passed in PARAMS, then its value is used as the
object class. Example:
$class->make_manager_methods(object_class => 'Product', ...);
If the "object_class" parameter is not passed, and if the target class inherits
from Rose::DB::Object::Manager and has also defined an "object_class" method, then
the return value of that method is used as the object class. Example:
package Product::Manager;
use Rose::DB::Object::Manager;
our @ISA = qw(Rose::DB::Object::Manager);
sub object_class { 'Product' }
# Assume object_class parameter is not part of the ... below
__PACKAGE__->make_manager_methods(...);
In this case, the object class would be "Product".
Finally, if none of the above conditions are met, one final option is considered.
If the target class inherits from Rose::DB::Object, then the object class is set
to the target class.
If the object class cannot be determined in one of the ways described above, then
a fatal error will occur.
• base name or method name
If a "base_name" parameter is passed in PARAMS, then its value is used as the base
name for the generated methods. Example:
$class->make_manager_methods(base_name => 'products', ...);
If the "base_name" parameter is not passed, and if there is only one argument
passed to the method, then the lone argument is used as the base name. Example:
$class->make_manager_methods('products');
(Note that, since the object class must be derived somehow, this will only work in
one of the situations (described above) where the object class can be derived from
the calling context or class.)
If a "methods" parameter is passed with a hash ref value, then each key of the
hash is used as the base name for the method types listed in the corresponding
value. (See method types below for more information.)
If a key of the "methods" hash ends in "()", then it is taken as the method name
and is used as is. For example, the key "foo" will be used as a base name, but
the key "foo()" will be used as a method name.
If the base name cannot be determined in one of the ways described above, then the
auto_manager_base_name method in the object_class's convention manager is called
on to supply a base name.
• method types
If an explicit list of method types is not passed to the method, then all of the
default_manager_method_types are created. Example:
# Base name is determined by convention manager auto_manager_base_name()
# method, all default method types created
$class->make_manager_methods();
# Base name is "products", all default method types created
$class->make_manager_methods('products');
# Base name is "products", all default method types created
$class->make_manager_methods(base_name => products', ...);
(Again, note that the object class must be derived somehow.)
If a "methods" parameter is passed, then its value must be a reference to a hash
whose keys are base names or method names, and whose values are method types or
references to arrays of method types.
If a key ends in "()", then it is taken as a method name and is used as is.
Otherwise, it is used as a base name. For example, the key "foo" will be used as
a base name, but the key "foo()" will be used as a method name.
If a key is a method name and its value specifies more than one method type, then
a fatal error will occur. (It's impossible to have more than one method with the
same name.)
Example:
# Make the following methods:
#
# * Base name: products; method types: objects, iterators
#
# get_products()
# get_products_iterator()
#
# * Method name: product_count; method type: count
#
# product_count()
#
$class->make_manager_methods(...,
methods =>
{
'products' => [ qw(objects iterator) ],
'product_count()' => 'count'
});
If the value of the "methods" parameter is not a reference to a hash, or if both
the "methods" and "base_name" parameters are passed, then a fatal error will
occur.
• target class
If a "target_class" parameter is passed in PARAMS, then its value is used as the
target class. Example:
$class->make_manager_methods(target_class => 'Product', ...);
If a "target_class" parameter is not passed, and if the calling class is not
Rose::DB::Object::Manager, then the calling class is used as the target class.
Otherwise, the class from which the method was called is used as the target class.
Examples:
# Target class is Product, regardless of the calling
# context or the value of $class
$class->make_manager_methods(target_class => 'Product', ...);
package Foo;
# Target class is Foo: no target_class parameter is passed
# and the calling class is Rose::DB::Object::Manager, so
# the class from which the method was called (Foo) is used.
Rose::DB::Object::Manager->make_manager_methods(
object_class => 'Bar',
base_name => 'Baz');
package Bar;
# Target class is Foo: no target_class parameter is passed
# and the calling class is not Rose::DB::Object::Manager,
# so the calling class (Foo) is used.
Foo->make_manager_methods(object_class => 'Bar',
base_name => 'Baz');
There's a lot of flexibility in this method's arguments (although some might use the
word "confusion" instead), but the examples can be pared down to a few common usage
scenarios.
The first is the recommended technique, as seen in the synopsis. Create a separate
manager class that inherits from Rose::DB::Object::Manager, override the
"object_class" method to specify the class of the objects being fetched, and then pass
a lone base name argument to the call to make_manager_methods.
package Product::Manager;
use Rose::DB::Object::Manager;
our @ISA = qw(Rose::DB::Object::Manager);
sub object_class { 'Product' }
__PACKAGE__->make_manager_methods('products');
The second example is used to install object manager methods directly into a
Rose::DB::Object-derived class. I do not recommend this practice; I consider it
"semantically impure" for the class that represents a single object to also be the
class that's used to fetch multiple objects. Inevitably, classes grow, and I'd like
the "object manager" class to be separate from the object class itself so they can
grow happily in isolation, with no potential clashes.
Also, keep in mind that Rose::DB::Object and Rose::DB::Object::Manager have separate
error_mode settings which must be synchronized or otherwise dealt with. Another
advantage of using a separate Rose::DB::Object::Manager subclass (as described
earlier) is that you can override the error_mode in your Rose::DB::Object::Manager
subclass only, rather than overriding the base class Rose::DB::Object::Manager
error_mode, which may affect other classes.
If none of that dissuades you, here's how to do it:
package Product;
use Rose::DB::Object:;
our @ISA = qw(Rose::DB::Object);
__PACKAGE__->make_manager_methods('products');
Finally, sometimes you don't want or need to use make_manager_methods at all. In
fact, this method did not exist in earlier versions of this module. The formerly
recommended way to use this class is still perfectly valid: subclass it and then call
through to the base class methods.
package Product::Manager;
use Rose::DB::Object::Manager;
our @ISA = qw(Rose::DB::Object::Manager);
sub get_products
{
shift->get_objects(object_class => 'Product', @_);
}
sub get_products_iterator
{
shift->get_objects_iterator(object_class => 'Product', @_);
}
sub get_products_count
{
shift->get_objects_count(object_class => 'Product', @_);
}
sub delete_products
{
shift->delete_objects(object_class => 'Product', @_);
}
sub update_products
{
shift->update_objects(object_class => 'Product', @_);
}
Of course, these methods will all look very similar in each
Rose::DB::Object::Manager-derived class. Creating these identically structured
methods is exactly what make_manager_methods automates for you.
But sometimes you want to customize these methods, in which case the "longhand"
technique above becomes essential. For example, imagine that we want to extend the
code in the synopsis, adding support for a "with_categories" parameter to the
"get_products()" method.
Product::Manager->get_products(date_created => '10/21/2001',
with_categories => 1);
...
sub get_products
{
my($class, %args) @_;
if(delete $args{'with_categories'}) # boolean flag
{
push(@{$args{'with_objects'}}, 'category');
}
Rose::DB::Object::Manager->get_objects(
%args, object_class => 'Product')
}
Here we've coerced the caller-friendly "with_categories" boolean flag parameter into
the "with_objects => [ 'category' ]" pair that Rose::DB::Object::Manager's get_objects
method can understand.
This is the typical evolution of an object manager method. It starts out as being
auto-generated by make_manager_methods, then becomes customized as new arguments are
added.
make_manager_method_from_sql [ NAME => SQL | PARAMS ]
Create a class method in the calling class that will fetch objects using a custom SQL
query. The method created will return a reference to an array of objects or a
Rose::DB::Object::Iterator object, depending on whether the "iterator" parameter is
set (see below).
Pass either a method name and an SQL query string or name/value parameters as
arguments. Valid parameters are:
iterator BOOL
If true, the method created will return a Rose::DB::Object::Iterator object.
object_class CLASS
The class name of the Rose::DB::Object-derived objects to be fetched. Defaults to
the value returned by the object_class class method.
params ARRAYREF
To allow the method that will be created to accept named parameters (name/value
pairs) instead of positional parameters, provide a reference to an array of
parameter names in the order that they should be passed to the call to DBI's
execute method.
method NAME
The name of the method to be created. This parameter is required.
prepare_cached BOOL
If true, then DBI's prepare_cached method will be used (instead of the prepare
method) when preparing the SQL statement that will fetch the objects. If omitted,
the default value is determined by the dbi_prepare_cached class method.
share_db BOOL
If true, "db" will be passed to each Rose::DB::Object-derived object when it is
constructed. Defaults to true.
sql SQL
The SQL query string. This parameter is required.
Each column returned by the SQL query must be either a column or method name in
"object_class". Column names take precedence in the case of a conflict.
Arguments passed to the created method will be passed to DBI's execute method when the
query is run. The number of arguments must exactly match the number of placeholders
in the SQL query. Positional parameters are required unless the "params" parameter is
used. (See description above.)
Returns a code reference to the method created.
Examples:
package Product::Manager;
use base 'Rose::DB::Object::Manager';
...
# Make method that takes no arguments
__PACKAGE__->make_manager_method_from_sql(get_odd_products =><<"EOF");
SELECT * FROM products WHERE sku % 2 != 0
EOF
# Make method that takes one positional parameter
__PACKAGE__->make_manager_method_from_sql(get_new_products =><<"EOF");
SELECT * FROM products WHERE release_date > ?
EOF
# Make method that takes named parameters
__PACKAGE__->make_manager_method_from_sql(
method => 'get_named_products',
params => [ qw(type name) ],
sql => <<"EOF");
SELECT * FROM products WHERE type = ? AND name LIKE ?
EOF
...
$products = Product::Manager->get_odd_products();
$products = Product::Manager->get_new_products('2005-01-01');
$products =
Product::Manager->get_named_products(
name => 'Kite%',
type => 'toy');
# Make method that takes named parameters and returns an iterator
__PACKAGE__->make_manager_method_from_sql(
method => 'get_named_products_iterator',
iterator => 1,
params => [ qw(type name) ],
sql => <<"EOF");
SELECT * FROM products WHERE type = ? AND name LIKE ?
EOF
$iterator =
Product::Manager->get_named_products_iterator(
name => 'Kite%',
type => 'toy');
while(my $product = $iterator->next)
{
... # do something with $product
$iterator->finish if(...); # finish early?
}
normalize_get_objects_args [ARGS]
This method takes ARGS in the forms accepted by get_objects (and other similar
methods) and normalizes them into name/value pairs. Since get_objects can take
arguments in many forms, this method is useful when overriding get_objects in a custom
Rose::DB::Object::Manager subclass. Example:
package Product::Manager;
use base 'Rose::DB::Object::Manager';
use Product;
sub object_class { 'Product' }
...
sub get_products
{
my($class, %args) = shift->normalize_get_objects_args(@_);
# Detect, extract, and handle custom argument
if(delete $args{'active_only'})
{
push(@{$args{'query'}}, status => 'active');
}
return $class->get_objects(%args); # call through to normal method
}
Now all of the following calls will work:
$products =
Product::Manager->get_products([ type => 'boat' ], sort_by => 'name');
$products =
Product::Manager->get_products({ name => { like => '%Dog%' } });
$products =
Product::Manager->get_products([ id => { gt => 123 } ], active_only => 1);
object_class
Returns the class name of the Rose::DB::Object-derived objects to be managed by this
class. Override this method in your subclass. The default implementation returns
undef.
perl_class_definition
Attempts to create the Perl source code that is equivalent to the current class. This
works best for classes created via Rose::DB::Object::Metadata's make_manager_class
method, but it will also work most of the time for classes whose methods were created
using make_manager_methods.
The Perl code is returned as a string. Here's an example:
package My::Product::Manager;
use My::Product;
use Rose::DB::Object::Manager;
our @ISA = qw(Rose::DB::Object::Manager);
sub object_class { 'My::Product' }
__PACKAGE__->make_manager_methods('products');
1;
update_objects [PARAMS]
Update rows in a table fronted by a Rose::DB::Object-derived class based on PARAMS,
where PARAMS are name/value pairs. Returns the number of rows updated, or undef if
there was an error.
Valid parameters are:
all BOOL
If set to a true value, this parameter indicates an explicit request to update all
rows in the table. If both the "all" and the "where" parameters are passed, a
fatal error will occur.
db DB
A Rose::DB-derived object used to access the database. If omitted, one will be
created by calling the init_db method of the "object_class".
object_class CLASS
The class name of the Rose::DB::Object-derived class that fronts the table whose
rows will to be updated. This parameter is required; a fatal error will occur if
it is omitted. Defaults to the value returned by the object_class class method.
set PARAMS
The names and values of the columns to be updated. PARAMS should be a reference
to a hash. Each key of the hash should be a column name or column get/set method
name. If a value is a simple scalar, then it is passed through the get/set method
that services the column before being incorporated into the SQL query.
If a value is a reference to a scalar, then it is dereferenced and incorporated
into the SQL query as-is.
If a value is a reference to a hash, then it must contain a single key named "sql"
and a corresponding value that will be incorporated into the SQL query as-is.
Example:
$num_rows_updated =
Product::Manager->update_products(
set =>
{
end_date => DateTime->now,
region_num => { sql => 'region_num * -1' }
count => \q(count + 1),
status => 'defunct',
},
where =>
[
status => [ 'stale', 'old' ],
name => { like => 'Wax%' }
or =>
[
start_date => { gt => '2008-12-30' },
end_date => { gt => 'now' },
],
]);
The call above would execute an SQL statement something like the one shown below
(depending on the database vendor, and assuming the current date was September
20th, 2005):
UPDATE products SET
end_date = '2005-09-20',
region_num = region_num * -1,
count = count + 1,
status = 'defunct'
WHERE
status IN ('stale', 'old') AND
name LIKE 'Wax%' AND
(
start_date > '2008-12-30' OR
end_date > '2005-09-20'
)
where PARAMS
The query parameters, passed as a reference to an array of name/value pairs.
These PARAMS are used to formulate the "where" clause of the SQL query that is
used to update the rows in the table. Arbitrarily nested boolean logic is
supported.
For the complete list of valid parameter names and values, see the documentation
for the "query" parameter of the build_select function in the
Rose::DB::Object::QueryBuilder module.
If this parameter is omitted, this method will refuse to update all rows in the
table and a fatal error will occur. To update all rows in a table, you must pass
the "all" parameter with a true value. If both the "all" and the "where"
parameters are passed, a fatal error will occur.
strict_ops [BOOL]
Get or set a boolean value that indicates whether using a comparison operator in the
"query" that is not listed in the Rose::DB::Object::QueryBuilder documentation will
cause a fatal error. The default value is false.
SUPPORT
For an informal overview of Rose::DB::Object, including Rose::DB::Object::Manager, consult
the Rose::DB::Object::Tutorial.
perldoc Rose::DB::Object::Tutorial
Any Rose::DB::Object::Manager questions or problems can be posted to the Rose::DB::Object
mailing list. To subscribe to the list or view the archives, go here:
<http://groups.google.com/group/rose-db-object>
Although the mailing list is the preferred support mechanism, you can also email the
author (see below) or file bugs using the CPAN bug tracking system:
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=Rose-DB-Object>
There's also a wiki and other resources linked from the Rose project home page:
<http://rose.googlecode.com>
AUTHOR
John C. Siracusa (siracusa@gmail.com)
LICENSE
Copyright (c) 2010 by John C. Siracusa. All rights reserved. This program is free
software; you can redistribute it and/or modify it under the same terms as Perl itself.