Execute a database command that reads

说明

final public MongoDB\Driver\Cursor MongoDB\Driver\Manager::executeReadCommand ( string $db , MongoDB\Driver\Command $command [, array $options = array() ] )

Selects a server according to the "readPreference" option and executes the command on that server. By default, the read preference from the MongoDB Connection URI will be used.

This method will apply logic that is specific to commands that read (e.g. » count) and take the MongoDB server version into account. The "readConcern" option will default to the corresponding value from the MongoDB Connection URI.

参数

db (string)

The name of the database on which to execute the command.

command (MongoDB\Driver\Command)

The command to execute.

options

**options**
Option	Type	Description
readConcern	MongoDB\Driver\ReadConcern	A read concern to apply to the operation. This option is available in MongoDB 3.2+ and will result in an exception at execution time if specified for an older server version.
readPreference	MongoDB\Driver\ReadPreference	A read preference to use for selecting a server for the operation.
session	MongoDB\Driver\Session	A session to associate with the operation.

返回值

Returns MongoDB\Driver\Cursor on success.

错误／异常

Throws MongoDB\Driver\Exception\InvalidArgumentException on argument parsing errors.
Throws MongoDB\Driver\Exception\ConnectionException if connection to the server fails (for reasons other than authentication).
Throws MongoDB\Driver\Exception\AuthenticationException if authentication is needed and fails.
Throws MongoDB\Driver\Exception\RuntimeException on other errors (e.g. invalid command).

参见

MongoDB\Driver\Command
MongoDB\Driver\Cursor
MongoDB\Driver\Manager::executeCommand() - Execute a database command
MongoDB\Driver\Manager::executeReadWriteCommand() - Execute a database command that reads and writes
MongoDB\Driver\Manager::executeWriteCommand() - Execute a database command that writes
MongoDB\Driver\Server::executeReadCommand() - Execute a database command that reads on this server