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.

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.

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.