oracular (3) MongoDB::Database.3pm.gz
NAME
MongoDB::Database - A MongoDB Database
VERSION
version v2.2.2
SYNOPSIS
# get a Database object via MongoDB::MongoClient
my $db = $client->get_database("foo");
# get a Collection via the Database object
my $coll = $db->get_collection("people");
# run a command on a database
my $res = $db->run_command([ismaster => 1]);
DESCRIPTION
This class models a MongoDB database. Use it to construct MongoDB::Collection objects. It also provides
the "run_command" method and some convenience methods that use it.
Generally, you never construct one of these directly with "new". Instead, you call "get_database" on a
MongoDB::MongoClient object.
USAGE
Error handling
Unless otherwise explicitly documented, all methods throw exceptions if an error occurs. The error types
are documented in MongoDB::Error.
To catch and handle errors, the Try::Tiny and Safe::Isa modules are recommended:
use Try::Tiny;
use Safe::Isa; # provides $_isa
try {
$db->run_command( @command )
}
catch {
if ( $_->$_isa("MongoDB::DuplicateKeyError" ) {
...
}
else {
...
}
};
To retry failures automatically, consider using Try::Tiny::Retry.
ATTRIBUTES
name
The name of the database.
read_preference
A MongoDB::ReadPreference object. It may be initialized with a string corresponding to one of the valid
read preference modes or a hash reference that will be coerced into a new MongoDB::ReadPreference object.
By default it will be inherited from a MongoDB::MongoClient object.
write_concern
A MongoDB::WriteConcern object. It may be initialized with a hash reference that will be coerced into a
new MongoDB::WriteConcern object. By default it will be inherited from a MongoDB::MongoClient object.
read_concern
A MongoDB::ReadConcern object. May be initialized with a hash reference or a string that will be coerced
into the level of read concern.
By default it will be inherited from a MongoDB::MongoClient object.
max_time_ms
Specifies the maximum amount of time in milliseconds that the server should use for working on a query.
Note: this will only be used for server versions 2.6 or greater, as that was when the $maxTimeMS meta-
operator was introduced.
bson_codec
An object that provides the "encode_one" and "decode_one" methods, such as from BSON. It may be
initialized with a hash reference that will be coerced into a new BSON object. By default it will be
inherited from a MongoDB::MongoClient object.
METHODS
client
$client = $db->client;
Returns the MongoDB::MongoClient object associated with this object.
list_collections
$result = $coll->list_collections( $filter );
$result = $coll->list_collections( $filter, $options );
Returns a MongoDB::QueryResult object to iterate over collection description documents. These will
contain "name" and "options" keys like so:
use boolean;
{
name => "my_capped_collection",
options => {
capped => true,
size => 10485760,
}
},
An optional filter document may be provided, which cause only collection description documents matching a
filter expression to be returned. See the listCollections command documentation
<http://docs.mongodb.org/manual/reference/command/listCollections/> for more details on filtering for
specific collections.
A hash reference of options may be provided. Valid keys include:
• "batchSize" – the number of documents to return per batch.
• "maxTimeMS" – the maximum amount of time in milliseconds to allow the command to run. (Note, this
will be ignored for servers before version 2.6.)
• "nameOnly" - query and return names of the collections only. Defaults to false. (Note, this will be
ignored for servers before version 4.0)
• "session" - the session to use for these operations. If not supplied, will use an implicit session.
For more information see MongoDB::ClientSession
NOTE: When using "nameOnly", the filter query must be empty or must only query the "name" field or else
no documents will be found.
collection_names
my @collections = $database->collection_names;
my @collections = $database->collection_names( $filter );
my @collections = $database->collection_names( $filter, $options );
Returns the list of collections in this database.
An optional filter document may be provided, which cause only collection description documents matching a
filter expression to be returned. See the listCollections command documentation
<http://docs.mongodb.org/manual/reference/command/listCollections/> for more details on filtering for
specific collections.
A hashref of options may also be provided.
Valid options include:
• "session" - the session to use for these operations. If not supplied, will use an implicit session.
For more information see MongoDB::ClientSession
Warning: if the number of collections is very large, this may return a very large result. Either pass an
appropriate filter, or use "list_collections" to iterate over collections instead.
get_collection, coll
my $collection = $database->get_collection('foo');
my $collection = $database->get_collection('foo', $options);
my $collection = $database->coll('foo', $options);
Returns a MongoDB::Collection for the given collection name within this database.
It takes an optional hash reference of options that are passed to the MongoDB::Collection constructor.
The "coll" method is an alias for "get_collection".
get_gridfsbucket, gfs
my $grid = $database->get_gridfsbucket;
my $grid = $database->get_gridfsbucket($options);
my $grid = $database->gfs($options);
This method returns a MongoDB::GridFSBucket object for storing and retrieving files from the database.
It takes an optional hash reference of options that are passed to the MongoDB::GridFSBucket constructor.
See MongoDB::GridFSBucket for more information.
The "gfs" method is an alias for "get_gridfsbucket".
drop
$database->drop;
Deletes the database.
A hashref of options may also be provided.
Valid options include:
• "session" - the session to use for these operations. If not supplied, will use an implicit session.
For more information see MongoDB::ClientSession
run_command
my $output = $database->run_command([ some_command => 1 ]);
my $output = $database->run_command(
[ some_command => 1 ],
{ mode => 'secondaryPreferred' }
);
my $output = $database->run_command(
[ some_command => 1 ],
$read_preference,
$options
);
This method runs a database command. The first argument must be a document with the command and its
arguments. It should be given as an array reference of key-value pairs or a Tie::IxHash object with the
command name as the first key. An error will be thrown if the command is not an ordered document.
By default, commands are run with a read preference of 'primary'. An optional second argument may
specify an alternative read preference. If given, it must be a MongoDB::ReadPreference object or a hash
reference that can be used to construct one.
A hashref of options may also be provided.
Valid options include:
• "session" - the session to use for these operations. If not supplied, will use an implicit session.
For more information see MongoDB::ClientSession
It returns the output of the command (a hash reference) on success or throws a MongoDB::DatabaseError
exception if the command fails.
For a list of possible database commands, run:
my $commands = $db->run_command([listCommands => 1]);
There are a few examples of database commands in the "DATABASE COMMANDS" in MongoDB::Examples section.
See also core documentation on database commands: <http://dochub.mongodb.org/core/commands>.
aggregate
Runs a query using the MongoDB 3.6+ aggregation framework and returns a MongoDB::QueryResult object.
The first argument must be an array-ref of aggregation pipeline
<http://docs.mongodb.org/manual/core/aggregation-pipeline/> documents. Each pipeline document must be a
hash reference.
The server supports several collection-less aggregation source stages like $currentOp and
$listLocalSessions.
$result = $database->aggregate( [
{
"\$currentOp" => {
allUsers => true,
},
},
] );
See Aggregation <http://docs.mongodb.org/manual/aggregation/> in the MongoDB manual for more information
on how to construct aggregation queries.
watch
Watches for changes on this database.
Perform an aggregation with an implicit initial $changeStream stage and returns a MongoDB::ChangeStream
result which can be used to iterate over the changes in the database. This functionality is available
since MongoDB 4.0.
my $stream = $db->watch();
my $stream = $db->watch( \@pipeline );
my $stream = $db->watch( \@pipeline, \%options );
while (1) {
# This inner loop will only run until no more changes are
# available.
while (my $change = $stream->next) {
# process $change
}
}
The returned stream will not block forever waiting for changes. If you want to respond to changes over a
longer time use "maxAwaitTimeMS" and regularly call "next" in a loop.
See "watch" in MongoDB::Collection for details on usage and available options.
AUTHORS
• David Golden <david@mongodb.com> • Rassi <rassi@mongodb.com> • Mike Friedman <friedo@friedo.com> • Kristina Chodorow <k.chodorow@gmail.com> • Florian Ragwitz <rafl@debian.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2020 by MongoDB, Inc.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004