MongoDB::execute
(PECL mongo >=0.9.3)
MongoDB::execute — Runs JavaScript code on the database server [deprecated]
Description
public array MongoDB::execute
(
mixed $code
[,
array $args = array()
] )
Warning
The » eval command,
which this method invokes, is deprecated in MongoDB 3.0+.
The Mongo database server runs a JavaScript engine. This method allows you
to run arbitary JavaScript on the database. This can be useful if you want
touch a number of collections lightly, or process some results on the
database side to reduce the amount that has to be sent to the client.
Running JavaScript in the database takes a write lock, meaning it blocks
other operations. Make sure you consider this before running a long script.
This is a wrapper for the
» eval database
command. This method is basically:
<?php
public function execute($code, $args) {
return $this->command(array('eval' => $code, 'args' => $args));
}
?>
MongoDB implies a return statement if you have a single statement on a single
line. This can cause some unintuitive behavior. For example, this returns
"foo":
<?php
$db->execute('"foo";');
?>
However, these return NULL:
<?php
$db->execute('"bar"; "foo";'); // more than one statement
$db->execute('db.foo.count(
);'); // more than one line
?>
To avoid surprising behavior, it is best not to depend on MongoDB to decide
what to return, but to explicitly state a return value. In the examples
above, we can change them to:
<?php
$db->execute('"bar"; return "foo";');
$db->execute('return db.foo.count(
);');
?>
Now the first statement will return "foo" and the second statement will
return a count of the "foo" collection.
Parameters
-
code
-
MongoCode or string to execute.
-
args
-
Arguments to be passed to code.
Return Values
Returns the result of the evaluation.
Examples
Example #1 Simple MongoDB::execute() example
<?php
$response = $db->execute("function() { return 'Hello, world!'; }");
echo $response['retval'];
?>
The above example will output
something similar to:
Hello, world!
Example #2 Parameter MongoDB::execute() example
The optional array of parameters will be passed to the JavaScript function.
<?php
$response = $db->execute("function(greeting, name) { return greeting+', '+name+'!'; }", array("Good bye", "Joe"));
echo $response['retval'];
?>
The above example will output
something similar to:
Good bye, Joe!
Example #3 Scope example
If a MongoCode object is used instead of a string for
the first parameter, a scope can be passed in which the JavaScript will be
executed.
<?php
$func =
"function(greeting, name) { ".
"return greeting+', '+name+', says '+greeter;".
"}";
$scope = array("greeter" => "Fred");
$code = new MongoCode($func, $scope);
$response = $db->execute($code, array("Goodbye", "Joe"));
echo $response['retval'];
?>
The above example will output
something similar to:
Goodbye, Joe, says Fred
