php - Find a document with ObjectID in mongoDB

Question

When I inserted some documents into a collection (without an ObjectID) mongoDB adds its own ObjectIDs.

I want to query a document by its unique ObjectID.

$db->collection_name->find(array('_id'=>'4e49fd8269fd873c0a000000')));

It does not work either with prefix of MongoID or ObjectID in front of '4e49fd8269fd873c0a000000'.

What is the proper way to query by ObjectID with mongoDB in PHP?

Answer 1

Pretty sure you have to use a MongoId object, eg

$item = $collection->findOne(array(
    '_id' => new MongoId('4e49fd8269fd873c0a000000')));

The notes on the Querying page are a little obtuse but it does mention...

Unless the user has specified otherwise, the _id field is a MongoId. The most common mistake is attepting to use a string to match a MongoId. Keep in mind that these are two different datatypes, and will not match each other in the same way that the string "array()" is not the same as an empty array