NAME¶
MongoDB::Database - A MongoDB Database
VERSION¶
version v0.705.0.0
SYNOPSIS¶
The MongoDB::Database class accesses to a database.
# accesses the foo database
my $db = $connection->foo;
You can also access databases with the "get_database($name)" in
MongoDB::Connection method.
NAME¶
MongoDB::Database - A Mongo database
SEE ALSO¶
Core documentation on databases:
<
http://dochub.mongodb.org/core/databases>.
ATTRIBUTES¶
name¶
The name of the database.
METHODS¶
collection_names¶
my @collections = $database->collection_names;
Returns the list of collections in this database.
get_collection ($name)¶
my $collection = $database->get_collection('foo');
Returns a MongoDB::Collection for the collection called $name within this
database.
get_gridfs ($prefix?)¶
my $grid = $database->get_gridfs;
Returns a MongoDB::GridFS for storing and retrieving files from the database.
Default prefix is "fs", making "$grid->files"
"fs.files" and "$grid->chunks" "fs.chunks".
See MongoDB::GridFS for more information.
drop¶
$database->drop;
Deletes the database.
last_error($options?)¶
my $err = $db->last_error({w => 2});
Finds out if the last database operation completed successfully. If the last
operation did not complete successfully, returns a hash reference of
information about the error that occurred.
The optional $options parameter is a hash reference that can contain any of the
following:
- w
- Guarantees that the previous operation will be replicated to "w"
servers before this command will return success. See
"MongoDB::Connection::w" for more information.
- wtimeout
- Milliseconds to wait for "w" copies of the data to be made. This
parameter should generally be specified, as the database will otherwise
wait forever if "w" copies cannot be made.
- fsync
- If true, behaves identically to "j" if journaling has been
turned on for "mongod".
If "mongod" is not running with journaling, then this option
requests that writes be immediately "sync"ed to disk if true.
This option can not be used simultaneously with the "j" flag.
- j
- If true, the client will block until write operations have been committed
to the server's journal. Prior to MongoDB 2.6, this option was ignored if
the server was running without journaling. Starting with MongoDB 2.6,
write operations will fail if this option is used when the server is
running without journaling.
"last_error" returns a hash with fields that vary, depending on what
the previous operation was and if it succeeded or failed. If the last
operation (before the "last_error" call) failed, either:
- "err" will be set or
- "errmsg" will be set and "ok" will be 0.
If "err" is "null" and "ok" is 1, the previous
operation succeeded.
The fields in the hash returned can include (but are not limited to):
- "ok"
- This should almost be 1 (unless "last_error" itself
failed).
- "err"
- If this field is non-null, an error occurred on the previous operation. If
this field is set, it will be a string describing the error that
occurred.
- "code"
- If a database error occurred, the relevant error code will be passed back
to the client.
- "errmsg"
- This field is set if something goes wrong with a database command. It is
coupled with "ok" being 0. For example, if "w" is set
and times out, "errmsg" will be set to "timed out waiting
for slaves" and "ok" will be 0. If this field is set, it
will be a string describing the error that occurred.
- "n"
- If the last operation was an update, upsert, or a remove, the number of
objects affected will be returned.
- "wtimeout"
- If the previous option timed out waiting for replication.
- "waited"
- How long the operation waited before timing out.
- "wtime"
- If "w" was set and the operation succeeded, how long it took to
replicate to "w" servers.
- "upserted"
- If an upsert occurred, this field will contain the new record's
"_id" field. For upserts, either this field or
"updatedExisting" will be present (unless an error
occurred).
- "updatedExisting"
- If an upsert updated an existing element, this field will be
"true". For upserts, either this field or "upserted"
will be present (unless an error occurred).
See "w" in MongoDB::Connection for more information.
run_command ($command)¶
my $result = $database->run_command({ some_command => 1 });
Runs a database command. Returns a string with the error message if the command
fails. Returns the result of the command (a hash reference) on success. For a
list of possible database commands, run:
my $commands = $db->run_command({listCommands => 1});
There are a few examples of database commands in the "DATABASE
COMMANDS" in MongoDB::Examples section.
See also core documentation on database commands:
<
http://dochub.mongodb.org/core/commands>.
eval ($code, $args?, $nolock?)¶
my $result = $database->eval('function(x) { return "hello, "+x; }', ["world"]);
Evaluate a JavaScript expression on the Mongo server. The $code argument can be
a string or an instance of MongoDB::Code. The $args are an optional array of
arguments to be passed to the $code function. $nolock (default
"false") prevents the eval command from taking the global write lock
before evaluating the JavaScript.
"eval" is useful if you need to touch a lot of data lightly; in such a
scenario the network transfer of the data could be a bottleneck. The $code
argument must be a JavaScript function. $args is an array of parameters that
will be passed to the function. $nolock is a boolean value. For more examples
of using eval see
<
http://www.mongodb.org/display/DOCS/Server-side+Code+Execution#Server-sideCodeExecution-Using{{db.eval%28%29}}>.
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