/ 
MongoDB-v2.1.0-TRIAL
River stage two • 48 direct dependents • 56 total dependents
/ MongoDB::Database

NAME

MongoDB::Database - A MongoDB Database

VERSION

version v2.1.0

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 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 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 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 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) 2019 by MongoDB, Inc.

This is free software, licensed under:

The Apache License, Version 2.0, January 2004