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  • Finding Documents using MongoCollection::findOne()

  • Finding Documents using MongoCollection::findOne
  • Finding Documents using MongoCollection::findOne()

    Finding Documents using MongoCollection::findOne()

    To show that the document we inserted in the
    previous step is stored in the database, we can do a simple
    MongoCollection::findOne() operation to
    get a single document from the collection. This method is useful
    when there is only one document matching the query or you are only
    interested in one result.

    = new MongoClient();
    $collection $connection->database->collectionName;

    $document $collection->findOne();
    var_dump$document );

    The above example will output:

    array(6) {
      object(MongoId)#8 (1) {
        string(24) "4e2995576803fab768000000"
      string(7) "MongoDB"
      string(8) "database"
      array(2) {
      array(3) {
        string(5) "0.9.7"
        string(5) "0.9.8"
        string(5) "0.9.9"

    Note that there is an _id field that has
    been added automatically to your document. _id is the
    “primary key” field. If your document does not specify one, the
    driver will add one automatically.

    If you specify your own _id field, it must
    be unique to the collection. See the example here:

    = new MongoClient();
    $db $connection->database;

    $db->foo->insert(array("_id" => 1));
    // this will throw an exception
    $db->foo->insert(array("_id" => 1));

    // this is fine, as it is a different collection
    $db->bar->insert(array("_id" => 1));

    By default the driver will ensure the server has
    acknowledged the write before returning. You can optionally turn
    this behaviour off by passing array(“w” => 0) as the
    second argument. This means that the driver should not wait for the
    database to acknowledge the write and would not throw the duplicate
    _id exception.

    See Also

    MongoCollection::findOne() for more
    information about finding data.

    MongoId goes into more detail on unique ids.

    The writes section covers writes in more depth, and the
    Write Concerns
    chapter goes into details of the various Write Concern options.