MongoDB\Driver\Server::executeReadCommand
(mongodb >=1.4.0)
MongoDB\Driver\Server::executeReadCommand — Execute a database command that reads on this server
说明
$db ,
MongoDB\Driver\Command $command [,
array $options = array() ] ) :
MongoDB\Driver\Cursor
Executes the command on this server.
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.
Note: The "readPreference" option does not control the server to which the driver issues the operation; it will always be executed on this server object. Instead, it may be used when issuing the operation to a secondary (from a replica set connection, not standalone) or mongos node to ensure that the driver sets the wire protocol accordingly or adds the read preference to the operation, respectively.
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.
WarningIf you are using a "session" which has a transaction in progress, you cannot specify a "readConcern" or "writeConcern" option. This will result in an MongoDB\Driver\Exception\InvalidArgumentException being thrown. Instead, you should set these two options when you create the transaction with MongoDB\Driver\Session::startTransaction().
返回值
Returns MongoDB\Driver\Cursor on success.
错误／异常
- Throws MongoDB\Driver\Exception\InvalidArgumentException if the "session" option is used with an associated transaction in combination with a "readConcern" or "writeConcern" option.
- 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\Server::executeCommand() - Execute a database command on this server
- MongoDB\Driver\Server::executeReadWriteCommand() - Execute a database command that reads and writes on this server
- MongoDB\Driver\Server::executeWriteCommand() - Execute a database command that writes on this server
- MongoDB\Driver\Manager::executeReadCommand() - Execute a database command that reads
