NAME¶
MongoDB::Collection - A MongoDB Collection
VERSION¶
version v0.705.0.0
SYNOPSIS¶
An instance of a MongoDB collection.
# gets the foo collection
my $collection = $db->get_collection( 'foo' );
Collection names can be chained together to access subcollections. For instance,
the collection "foo.bar" can be accessed with either:
my $collection = $db->get_collection( 'foo' )->get_collection( 'bar' );
or
my $collection = $db->get_collection( 'foo.bar' );
ATTRIBUTES¶
name¶
The name of the collection.
full_name¶
The full_name of the collection, including the namespace of the database it's
in.
METHODS¶
get_collection ($name)¶
my $collection = $database->get_collection('foo');
Returns a MongoDB::Collection for the collection called $name within this
collection.
find($query)¶
my $cursor = $collection->find({ i => { '$gt' => 42 } });
Executes the given $query and returns a "MongoDB::Cursor" with the
results. $query can be a hash reference, Tie::IxHash, or array reference (with
an even number of elements).
The set of fields returned can be limited through the use of the
"MongoDB::Cursor::fields" method on the resulting MongoDB::Cursor
object. Other commonly used cursor methods are
"MongoDB::Cursor::limit", "MongoDB::Cursor::skip", and
"MongoDB::Cursor::sort".
See also core documentation on querying:
<
http://docs.mongodb.org/manual/core/read/>.
query($query, $attrs?)¶
Identical to "MongoDB::Collection::find", described above.
my $cursor = $collection->query->limit(10)->skip(10);
my $cursor = $collection->query({ location => "Vancouver" })->sort({ age => 1 });
Valid query attributes are:
- limit
- Limit the number of results.
- skip
- Skip a number of results.
- sort_by
- Order results.
find_one($query, $fields?)¶
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 $fields is specified, the resulting document will only include
the fields given (and the "_id" field) which can cut down on wire
traffic.
insert ($object, $options?)¶
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.
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.
See also core documentation on insert:
<
http://docs.mongodb.org/manual/core/create/>.
batch_insert (\@array, $options)¶
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.
update (\%criteria, \%object, \%options?)¶
$collection->update({'x' => 3}, {'$inc' => {'count' => -1} }, {"upsert" => 1, "multiple" => 1});
Updates an existing $object matching $criteria in the database.
Returns 1 unless the "safe" option is set. If "safe" is set,
this will return a hash of information about the update, including number of
documents updated ("n"). If "safe" is set and the update
fails, "update" will croak. You can also check if the update
succeeded by doing an unsafe update, then calling
"last_error($options?)" in MongoDB::Database.
"update" can take a hash reference of options. The options currently
supported are:
- "upsert" If no object matching $criteria is found, $object will
be inserted.
- "multiple" All of the documents that match $criteria will be
updated, not just the first document found. (Only available with database
version 1.1.3 and newer.)
- "safe" If the update fails and safe is set, the update will
croak.
See also core documentation on update:
<
http://docs.mongodb.org/manual/core/update/>.
initialize_ordered_bulk_op¶
my $bulk = $collection->initialize_ordered_bulk_op;
$bulk->insert( $doc1 );
$bulk->insert( $doc2 );
...
my $result = $bulk->execute;
Returns a MongoDB::BulkWrite object to group write operations into fewer network
round-trips. This method creates an
ordered operation, where operations
halt after the first error. See MongoDB::BulkWrite for more details.
The method "ordered_bulk" may be used as an alias for
"initialize_ordered_bulk_op".
initialize_unordered_bulk_op¶
This method works just like "initialize_ordered_bulk_op" except that
the order that operations are sent to the database is not guaranteed and
errors do not halt processing. See MongoDB::BulkWrite for more details.
The method "unordered_bulk" may be used as an alias for
"initialize_unordered_bulk_op".
find_and_modify¶
my $result = $collection->find_and_modify( { query => { ... }, update => { ... } } );
Perform an atomic update. "find_and_modify" guarantees that nothing
else will come along and change the queried documents before the update is
performed.
Returns the old version of the document, unless "new =" 1> is
specified. If no documents match the query, it returns nothing.
aggregate¶
my $result = $collection->aggregate( [ ... ] );
Run a query using the MongoDB 2.2+ aggregation framework. The first argument is
an array-ref of aggregation pipeline operators.
The type of return value from "aggregate" depends on how you use it.
- •
- By default, the aggregation framework returns a document with an embedded
array of results, and the "aggregate" method returns a reference
to that array.
- •
- MongoDB 2.6+ supports returning cursors from aggregation queries, allowing
you to bypass the 16MB size limit of documents. If you specifiy a
"cursor" option, the "aggregate" method will return a
MongoDB::Cursor object which can be iterated in the normal fashion.
my $cursor = $collection->aggregate( [ ... ], { cursor => 1 } );
Specifying a "cursor" option will cause an error on versions of
MongoDB below 2.6.
The "cursor" option may also have some useful options of its own.
Currently, the only one is "batchSize", which allows you to
control how frequently the cursor must go back to the database for more
documents.
my $cursor = $collection->aggregate( [ ... ], { cursor => { batchSize => 10 } } );
- •
- MongoDB 2.6+ supports an "explain" option to aggregation queries
to retrieve data about how the server will process a query pipeline.
my $result = $collection->aggregate( [ ... ], { explain => 1 } );
In this case, "aggregate" will return a document (not an array)
containing the explanation structure.
- •
- Finally, MongoDB 2.6+ will return an empty results array if the $out
pipeline operator is used to write aggregation results directly to a
collection. Create a new "Collection" object to query the result
collection.
See Aggregation <
http://docs.mongodb.org/manual/aggregation/> in the
MongoDB manual for more information on how to construct aggregation queries.
parallel_scan($max_cursors)¶
my @cursors = $collection->parallel_scan(10);
Scan the collection in parallel. The argument is the maximum number of
MongoDB::Cursor objects to return and must be a positive integer between 1 and
10,000.
As long as the collection is not modified during scanning, each document will
appear only once in one of the cursors' result sets.
Only iteration methods may be called on parallel scan cursors.
If an error occurs, an exception will be thrown.
rename ("newcollectionname")¶
my $newcollection = $collection->rename("mynewcollection");
Renames the collection. It expects that the new name is currently not in use.
Returns the new collection. If a collection already exists with that new
collection name this will die.
save($doc, $options)¶
$collection->save({"author" => "joe"});
my $post = $collection->find_one;
$post->{author} = {"name" => "joe", "id" => 123, "phone" => "555-5555"};
$collection->save( $post );
$collection->save( $post, { safe => 1 } )
Inserts a document into the database if it does not have an _id field, upserts
it if it does have an _id field.
The return types for this function are a bit of a mess, as it will return the
_id if a new document was inserted, 1 if an upsert occurred, and croak if the
safe option was set and an error occurred. You can also check if the save
succeeded by doing an unsafe save, then calling
"last_error($options?)" in MongoDB::Database.
remove ($query?, $options?)¶
$collection->remove({ answer => { '$ne' => 42 } });
Removes all objects matching the given $query from the database. If no
parameters are given, removes all objects from the collection (but does not
delete indexes, as "MongoDB::Collection::drop" does).
Returns 1 unless the "safe" option is set. If "safe" is set
and the remove succeeds, "remove" will return a hash of information
about the remove, including how many documents were removed ("n").
If the remove fails and "safe" is set, "remove" will
croak. You can also check if the remove succeeded by doing an unsafe remove,
then calling "last_error($options?)" in MongoDB::Database.
"remove" can take a hash reference of options. The options currently
supported are
- "just_one" Only one matching document to be removed.
- "safe" If the update fails and safe is set, this function will
croak.
See also core documentation on remove:
<
http://docs.mongodb.org/manual/core/delete/>.
ensure_index ($keys, $options?)¶
use boolean;
$collection->ensure_index({"foo" => 1, "bar" => -1}, { unique => true });
Makes sure the given $keys of this collection are indexed. $keys can be an array
reference, hash reference, or "Tie::IxHash". "Tie::IxHash"
is preferred for multi-key indexes, so that the keys are in the correct order.
1 creates an ascending index, -1 creates a descending index.
If the "safe" option is not set, "ensure_index" will not
return anything unless there is a socket error (in which case it will croak).
If the "safe" option is set and the index creation fails, it will
also croak. You can also check if the indexing succeeded by doing an unsafe
index creation, then calling "last_error($options?)" in
MongoDB::Database.
See the MongoDB::Indexing pod for more information on indexing.
count($query?)¶
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.
validate¶
$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.
drop_indexes¶
$collection->drop_indexes;
Removes all indexes from this collection.
drop_index ($index_name)¶
$collection->drop_index('foo_1');
Removes an index called $index_name from this collection. Use
"MongoDB::Collection::get_indexes" to find the index name.
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' => '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.
drop¶
$collection->drop;
Deletes a collection as well as all of its indexes.
AUTHORS¶
- •
- David Golden <david.golden@mongodb.org>
- •
- Mike Friedman <friedo@mongodb.com>
- •
- Kristina Chodorow <kristina@mongodb.org>
- •
- Florian Ragwitz <rafl@debian.org>
COPYRIGHT AND LICENSE¶
This software is Copyright (c) 2014 by MongoDB, Inc..
This is free software, licensed under:
The Apache License, Version 2.0, January 2004