Provided by: libpgobject-perl_2.000002-1_all 
NAME
PGObject - A toolkit integrating intelligent PostgreSQL dbs into Perl objects
VERSION
Version 2.0.2
SYNPOSIS
To use without caching:
use PGObject;
To use with caching:
use PGObject ':cache';
To get basic info from a function
my $f_info = PGObject->function_info(
dbh => $dbh,
funcname => $funcname,
funcschema => 'public',
);
To get info about a function, filtered by first argument type
my $f_info = PGObject->function_info(
dbh => $dbh,
funcname => $funcname,
funcschema => 'public',
funcprefix => 'test__',
objtype => 'invoice',
objschema => 'public',
);
To call a function with enumerated arguments
my @results = PGObject->call_procedure(
dbh => $dbh,
funcname => $funcname,
funcprefix => 'test__',
funcschema => $funcname,
args => [$arg1, $arg2, $arg3],
);
To do the same with a running total
my @results = PGObject->call_procedure(
dbh => $dbh,
funcname => $funcname,
funcschema => $funcname,
args => [$arg1, $arg2, $arg3],
running_funcs => [{agg => 'sum(amount)', alias => 'running_total'}],
);
DESCRIPTION
PGObject contains the base routines for object management using discoverable stored
procedures in PostgreSQL databases. This module contains only common functionality and
support structures, and low-level API's. Most developers will want to use more functional
modules which add to these functions.
The overall approach here is to provide the basics for a toolkit that other modules can
extend. This is thus intended to be a component for building integration between
PostgreSQL user defined functions and Perl objects.
Because decisions such as state handling are largely outside of the scope of this module,
this module itself does not do any significant state handling. Database handles (using
DBD::Pg 2.0 or later) must be passed in on every call. This decision was made in order to
allow for diversity in this area, with the idea that wrapper classes would be written to
implement this.
FUNCTIONS
clear_info_cache
This function clears the info cache if this was loaded with caching enabled.
The cache is also automatically cleared when a function that was run could not be found
(this could be caused by updating the db).
function_info(%args)
Arguments:
dbh (required)
Database handle
funcname (required)
function name
funcschema (optional, default 'public')
function schema
funcprefix (optiona, default '')
Prefix for the function. This can be useful for separating functions by class.
argtype1 (optional)
Name of first argument type. If not provided, does not filter on this criteria.
argschema (optional)
Name of first argument type's schema. If not provided defaults to 'public'
This function looks up basic mapping information for a function. If more than one
function is found, an exception is raised. This function is primarily intended to be used
by packages which extend this one, in order to accomplish stored procedure to object
mapping.
Return data is a hashref containing the following elements:
args
This is an arrayref of hashrefs, each of which contains 'name' and 'type'
name
The name of the function
num_args
The number of arguments
call_procedure(%args)
Arguments:
funcname
The function name
funcschema
The schema in which the function resides
funcprefix (optiona, default '')
Prefix for the function. This can be useful for separating functions by class.
args
This is an arrayref. Each item is either a literal value, an arrayref, or a hashref
of extended information. In the hashref case, the type key specifies the string to
use to cast the type in, and value is the value.
orderby
The list (arrayref) of columns on output for ordering.
running_funcs
An arrayref of running windowed aggregates. Each contains two keys, namely 'agg' for
the aggregate and 'alias' for the function name.
These are aggregates, each one has appended 'OVER (ROWS UNBOUNDED PRECEDING)' to it.
registry
This is the name of the registry used for type conversion. It can be omitted and
defaults to 'default.' Note that use of a non-standard registry currently does *not*
merge changes from the default registry, so you need to reregister types in non-
default registries when you create them.
Please note, these aggregates are not intended to be user-supplied. Please only allow
whitelisted values here or construct in a tested framework elsewhere. Because of the
syntax here, there is no sql injection prevention possible at the framework level for
this parameter.
new_registry($registry_name)
Creates a new registry if it does not exist. This is useful when segments of an
application must override existing type mappings.
This is deprecated and throws a warning.
Use PGObject::Type::Registry->new_registry($registry_name) instead.
This no longer returns anything of significance.
register_type(pgtype => $tname, registry => $regname, perl_class => $pm)
DEPRECATED
Registers a type as a class. This means that when an attribute of type $pg_type is
returned, that PGObject will automatically return whatever $perl_class->from_db returns.
This allows you to have a db-specific constructor for such types.
The registry argument is optional and defaults to 'default'
If the registry does not exist, an error is raised. if the pg_type is already registered
to a different type, this returns 0. Returns 1 on success.
Use PGObject::Type::Registry->register_type() instead.
unregister_type(pgtype => $tname, registry => $regname)
Deprecated.
Tries to unregister the type. If the type does not exist, returns 0, otherwise returns 1.
This is mostly useful for when a specific type must make sure it has the slot. This is
rarely desirable. It is usually better to use a subregistry instead.
WRITING PGOBJECT-AWARE HELPER CLASSES
One of the powerful features of PGObject is the ability to declare methods in types which
can be dynamically detected and used to serialize data for query purposes. Objects which
contain a pgobject_to_db() or a to_db() method, that method will be called and the return
value used in place of the object. This can allow arbitrary types to serialize themselves
in arbitrary ways.
For example a date object could be set up with such a method which would export a string
in yyyy-mm-dd format. An object could look up its own definition and return something
like :
{ cast => 'dbtypename', value => '("A","List","Of","Properties")'}
If a scalar is returned that is used as the serialized value. If a hashref is returned,
it must follow the type format:
type => variable binding type,
cast => db cast type
value => literal representation of type, as intelligible by DBD::Pg
REQUIRED INTERFACES
Registered types MUST implement a $class->from_db function accepts the string from the
database as its only argument, and returns the object of the desired type.
Any type MAY present an $object->to_db() interface, requiring no arguments, and returning
a valid value. These can be hashrefs as specified above, arrayrefs (converted to
PostgreSQL arrays by DBD::Pg) or scalar text values.
UNDERSTANDING THE REGISTRY SYSTEM
Note that 2.0 moves the registry to a service module which handles both registry and
deserialization of database types. This is intended to be both cleaner and more flexible
than the embedded system in 1.x.
The registry system allows Perl classes to "claim" PostgreSQL types within a certain
domain. For example, if I want to ensure that all numeric types are turned into
Math::BigFloat objects, I can build a wrapper class with appropriate interfaces, but
PGObject won't know to convert numeric types to this new class, so this is what
registration is for.
By default, these mappings are fully global. Once a class claims a type, unless another
type goes through the trouble of unregisterign the first type and making sure it gets the
authoritative spot, all items of that type get turned into the appropriate Perl object
types. While this is sufficient for the vast number of applications, however, there may
be cases where names conflict across schemas or the like. To address this application
components may create their own registries. Each registry is fully global, but
application components can specify non-standard registries when calling procedures, and
PGObject will use only those components registered on the non-standard registry when
checking rows before output.
Backwards Incompatibilities from 1.x
Deserialization occurs in a context which specifies a registry. In 1.x there were no
concerns about default mappings but now this triggers a warning. The most basic and
frequently used portions of this have been kept but return values for registering types
has changed. We no longer provide a return variable but throw an exception if the type
cannot be safely registered.
This follows a philosophy of throwing exceptions when guarantees cannot be met.
We now throw warnings when the default registry is used.
Longer-run, deserializers should use the PGObject::Type::Registry interface directly.
WRITING TOP-HALF OBJECT FRAMEWORKS FOR PGOBJECT
PGObject is intended to be the database-facing side of a framework for objects. The
intended structure is for three tiers of logic:
Database facing, low-level API's
Object management modules
Application handlers with things like database connection management.
By top half, we are referring to the second tier. The third tier exists in the client
application.
The PGObject module provides only low-level API's in that first tier. The job of this
module is to provide database function information to the upper level modules.
We do not supply type information, If your top-level module needs this, please check out
https://code.google.com/p/typeutils/ which could then be used via our function mapping
APIs here.
Safely Handling Memoization of Catalog Lookups
It is important to remember, when writing PGObject top half frameworks that the catalog
lookups may be memoized and may come back as a data structure. This means that changes to
the structures returned from get_function_info() in this module and similar functions in
other catalog-bound modules may not be safe to modify in arbitrary ways. Therefore we
recommend that the return values from catalog-lookup functions are treated as immutable.
Normalizing output is safe provided there are no conflicts between naming conventions.
This is usually true since different naming conventions would interfere withmapping.
However, there could be cases where it is not true, for example, where two different
mapping modules agree on a subset of normalization conventions but differ on some details.
The two might safely handle the same conventions but normalize differently resulting in
conflicts of both were used.
A BRIEF GUIDE TO THE NAMESPACE LAYOUT
Most names underneath PGObject can be assumed to be top-half modules and modules under
those can be generally assumed to be variants on those. There are, however, a few
reserved names:
::Debug is reserved for debugging information. For example, functions which retrieve
sources of functions, or grab diagnostics, or the like would go here.
::Test is reserved for test framework extensions applible only here
::Type is reserved for PG aware type classes.
For example, one might have PGObject::Type::BigFloat for a Math::Bigfloat wrapper, or
PGObject::Type::DateTime for a DateTime wrapper.
::Util is reserved for utility functions and classes.
AUTHOR
Chris Travers, "<chris.travers at gmail.com>"
BUGS
Please report any bugs or feature requests to "bug-pgobject at rt.cpan.org", or through
the web interface at <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=PGObject>. I will be
notified, and then you'll automatically be notified of progress on your bug as I make
changes.
SUPPORT
You can find documentation for this module with the perldoc command.
perldoc PGObject
You can also look for information at:
• RT: CPAN's request tracker (report bugs here)
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=PGObject>
• AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/PGObject>
• CPAN Ratings
<http://cpanratings.perl.org/d/PGObject>
• Search CPAN
<http://search.cpan.org/dist/PGObject/>
ACKNOWLEDGEMENTS
This code has been loosely based on code written for the LedgerSMB open source accounting
and ERP project. While that software uses the GNU GPL v2 or later, this is my own
reimplementation, based on my original contributions to that project alone, and it differs
in significant ways. This being said, without LedgerSMB, this module wouldn't exist, and
without the lessons learned there, and the great people who have helped make this
possible, this framework would not be half of what it is today.
SEE ALSO
PGObject::Simple - Simple mapping of object properties to stored proc args
PGObject::Simple::Role - Moose-enabled wrapper for PGObject::Simple
COPYRIGHT
COPYRIGHT (C) 2013-2014 Chris Travers COPYRIGHT (C) 2014-2017 The LedgerSMB Core Team
Redistribution and use in source and compiled forms with or without modification, are
permitted provided that the following conditions are met:
• Redistributions of source code must retain the above copyright notice, this list of
conditions and the following disclaimer as the first lines of this file unmodified.
• Redistributions in compiled form must reproduce the above copyright notice, this list
of conditions and the following disclaimer in the source code, documentation, and/or
other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.