MongoDB::Database

Operations on a MongoDB database

Description

Creating a MongoDB database will not happen when a Raku MongoDB::Database is created. Databases and collections are created only when documents are first inserted. The method run-command() is the most used vehicle to operate on a database and collections. Almost nothing else matters.

Example

# Initialize using the default hostname and port values
my MongoDB::Client $client .= new(:uri<mongodb://>);

# Get the database mydatabase
my MongoDB::Database $database = $client.database('mydatabase');

# And drop the database
$database.run-command: dropDatabase => 1;

Methods

new

Define a database object. The database is created (if not existant) the moment that data is stored in a collection.

submethod BUILD ( MongoDB::Uri:D :$uri-obj!, Str:D :$name! )

• MongoDB::Uri $uri-obj; the object that describes the uri provided to the client.

• Str $name; Name of the database.

Example 1

my MongoDB::Client $client .= new(:uri<mongodb://>);
my MongoDB::Database $database .= new(
  $client.uri-obj, :name<mydatabase>
);

Example 2

The slightly easier way is using the client to create a database object;

my MongoDB::Client $client .= new(:uri<mongodb://>);
my MongoDB::Database $database = $client.database('mydatabase');

Select collection and return a collection object. The collection is only created when data is inserted.

method collection ( Str:D $name --> MongoDB::Collection )

name

The name of the database.

method name ( --> Str )

Run a command against the database. For proper handling of this command it is necessary to study the documentation on the MongoDB site. A good starting point is at this page.

See also Perl6 docs here and here and BSON::Document

method run-command ( BSON::Document:D $command --> BSON::Document )

• $command; A BSON::Document or a List of Pair. A structure which defines the command to send to the server.

The command returns always (almost always …) a BSON::Document. Check for its definedness and when defined check the ok key to see if the command was successful

Example

This example shows how to insert a document. See also information here. We insert a document using information from http://perldoc.perl.org/perlhist.html. Note that I have a made typo in Larry’s name on purpose. We will correct this in the second example.

Insert a document into collection ‘famous_people’

my BSON::Document $req .= new: (
  insert => 'famous_people',
  documents => [ (
      name => 'Larry',
      surname => 'Walll',
      languages => (
        Perl0 => 'introduced Perl to my officemates.',
        Perl1 => 'introduced Perl to the world',
        Perl2 => 'introduced Henry Spencer\'s regular expression package.',
        Perl3 => 'introduced the ability to handle binary data.',
        Perl4 => 'introduced the first Camel book.',
        Perl5 => 'introduced everything else,'
                 ~ ' including the ability to introduce everything else.',
        Perl6 => 'A perl changing perl event, Dec 24, 2015',
        Raku => 'Renaming Perl6 into Raku, Oct 2019'
      ),
    ),
  ]
);

# Run the command with the insert request
BSON::Document $doc = $database.run-command($req);
if $doc<ok> == 1 { # "Result is ok"
  …
}

# Now search for something
my BSON::Document $doc = $database.run-command: (
  findAndModify => 'famous_people',
  query => (surname => 'Walll'),
  update => ('$set' => (surname => 'Wall')),
);

if $doc<ok> == 1 { # "Result is ok"
  note "Old data: ", $doc<value><surname>;
  note "Updated: ", $doc<lastErrorObject><updatedExisting>;
  …
}

Please also note that mongodb uses query selectors such as $set above and virtual collections like $cmd. Because they start with a ‘$’ these must be protected against evaluation by Raku using single quotes. These names are used as keys and unfortunately you can not use the named argument notation like it is possible for e.g. :findAndModify<famous_people>.