MongoDB::Collection - A Mongo collection
An instance of a MongoDB collection.
# gets the foo collection my $collection = $db->foo;
Collection names can be chained together to access subcollections. For instance, the collection foo.bar can be accessed with:
foo.bar
my $collection = $db->foo->bar;
You can also access collections with the "get_collection" in MongoDB::Database method.
Core documentation on collections: http://dochub.mongodb.org/core/collections.
The name of the collection.
The full_name of the collection, including the namespace of the database it's in.
$name = MongoDB::Collection::to_index_string({age : 1});
Takes a Tie::IxHash, hash reference, or array reference. Converts it into an index string.
my $cursor = $collection->find({ i => { '$gt' => 42 } });
Executes the given $query and returns a MongoDB::Cursor with the results. $query can be a hash reference, Tie::IxHash, or array reference (with an even number of elements).
$query
MongoDB::Cursor
The set of fields returned can be limited through the use of the MongoDB::Cursor::fields method on the resulting MongoDB::Cursor object. Other commonly used cursor methods are MongoDB::Cursor::limit, MongoDB::Cursor::skip, and MongoDB::Cursor::sort.
MongoDB::Cursor::fields
MongoDB::Cursor::limit
MongoDB::Cursor::skip
MongoDB::Cursor::sort
See also core documentation on querying: http://dochub.mongodb.org/core/find.
Identical to MongoDB::Collection::find, described above.
MongoDB::Collection::find
my $cursor = $collection->query->limit(10)->skip(10); my $cursor = $collection->query({ location => "Vancouver" })->sort({ age => 1 });
Valid query attributes are:
Limit the number of results.
Skip a number of results.
Order results.
my $object = $collection->find_one({ name => 'Resi' }); my $object = $collection->find_one({ name => 'Resi' }, { name => 1, age => 1});
Executes the given $query and returns the first object matching it. $query can be a hash reference, Tie::IxHash, or array reference (with an even number of elements). If $fields is specified, the resulting document will only include the fields given (and the _id field) which can cut down on wire traffic.
$fields
_id
my $id1 = $coll->insert({ name => 'mongo', type => 'database' }); my $id2 = $coll->insert({ name => 'mongo', type => 'database' }, {safe => 1});
Inserts the given $object into the database and returns it's id value. $object can be a hash reference, a reference to an array with an even number of elements, or a Tie::IxHash. The id is the _id value specified in the data or a MongoDB::OID.
$object
The optional $options parameter can be used to specify if this is a safe insert. A safe insert will check with the database if the insert succeeded and croak if it did not. You can also check if the insert succeeded by doing an unsafe insert, then calling "last_error($options?)" in MongoDB::Database.
$options
See also core documentation on insert: http://dochub.mongodb.org/core/insert.
my @ids = $collection->batch_insert([{name => "Joe"}, {name => "Fred"}, {name => "Sam"}]);
Inserts each of the documents in the array into the database and returns an array of their _id fields.
The optional $options parameter can be used to specify if this is a safe insert. A safe insert will check with the database if the insert succeeded and croak if it did not. You can also check if the inserts succeeded by doing an unsafe batch insert, then calling "last_error($options?)" in MongoDB::Database.
$collection->update({'x' => 3}, {'$inc' => {'count' => -1} }, {"upsert" => 1, "multiple" => 1});
Updates an existing $object matching $criteria in the database.
$criteria
Returns 1 unless the safe option is set. If safe is set, this will return a hash of information about the update, including number of documents updated (n). If safe is set and the update fails, update will croak. You can also check if the update succeeded by doing an unsafe update, then calling "last_error($options?)" in MongoDB::Database.
safe
n
update
update can take a hash reference of options. The options currently supported are:
upsert
multiple
See also core documentation on update: http://dochub.mongodb.org/core/update.
my $newcollection = $collection->rename("mynewcollection");
Renames the collection. It expects that the new name is currently not in use.
Returns the new collection. If a collection already exists with that new collection name this will die.
$collection->remove({ answer => { '$ne' => 42 } });
Removes all objects matching the given $query from the database. If no parameters are given, removes all objects from the collection (but does not delete indexes, as MongoDB::Collection::drop does).
MongoDB::Collection::drop
Returns 1 unless the safe option is set. If safe is set and the remove succeeds, remove will return a hash of information about the remove, including how many documents were removed (n). If the remove fails and safe is set, remove will croak. You can also check if the remove succeeded by doing an unsafe remove, then calling "last_error($options?)" in MongoDB::Database.
remove
remove can take a hash reference of options. The options currently supported are
just_one
See also core documentation on remove: http://dochub.mongodb.org/core/remove.
use boolean; $collection->ensure_index({"foo" => 1, "bar" => -1}, { unique => true });
Makes sure the given $keys of this collection are indexed. $keys can be an array reference, hash reference, or Tie::IxHash. Tie::IxHash is preferred for multi-key indexes, so that the keys are in the correct order. 1 creates an ascending index, -1 creates a descending index.
$keys
Tie::IxHash
If the safe option is not set, ensure_index will not return anything unless there is a socket error (in which case it will croak). If the safe option is set and the index creation fails, it will also croak. You can also check if the indexing succeeded by doing an unsafe index creation, then calling "last_error($options?)" in MongoDB::Database.
ensure_index
See the MongoDB::Indexing pod for more information on indexing.
$collection->save({"author" => "joe"}); my $post = $collection->find_one; $post->{author} = {"name" => "joe", "id" => 123, "phone" => "555-5555"}; $collection->save($post);
Inserts a document into the database if it does not have an _id field, upserts it if it does have an _id field.
safe =
If the save fails and safe is set, this function will croak.
The return types for this function are a bit of a mess, as it will return the _id if a new document was inserted, 1 if an upsert occurred, and croak if the safe option was set and an error occurred. You can also check if the save succeeded by doing an unsafe save, then calling "last_error($options?)" in MongoDB::Database.
my $n_objects = $collection->count({ name => 'Bob' });
Counts the number of objects in this collection that match the given $query. If no query is given, the total number of objects in the collection is returned.
$collection->validate;
Asks the server to validate this collection. Returns a hash of the form:
{ 'ok' => '1', 'ns' => 'foo.bar', 'result' => info }
where info is a string of information about the collection.
info
$collection->drop_indexes;
Removes all indexes from this collection.
$collection->drop_index('foo_1');
Removes an index called $index_name from this collection. Use MongoDB::Collection::get_indexes to find the index name.
$index_name
MongoDB::Collection::get_indexes
my @indexes = $collection->get_indexes;
Returns a list of all indexes of this collection. Each index contains ns, name, and key fields of the form:
ns
name
key
{ 'ns' => 'db_name.collection_name', 'name' => 'index_name', 'key' => { 'key1' => dir1, 'key2' => dir2, ... 'keyN' => dirN } }
where dirX is 1 or -1, depending on if the index is ascending or descending on that key.
dirX
$collection->drop;
Deletes a collection as well as all of its indexes.
Kristina Chodorow <kristina@mongodb.org>
To install MongoDB, copy and paste the appropriate command in to your terminal.
cpanm
cpanm MongoDB
CPAN shell
perl -MCPAN -e shell install MongoDB
For more information on module installation, please visit the detailed CPAN module installation guide.