Tutorial

Introduction

This is the 10gen-supported PHP driver for MongoDB.

Here's a quick code sample that connects, inserts documents, queries for documents, iterates through query results, and disconnects from MongoDB. There are more details on each step in the tutorial below.


<?php

// connect
$m = new Mongo();

// select a database
$db = $m->comedy;

// select a collection (analogous to a relational database's table)
$collection = $db->cartoons;

// add a record
$obj = array( "title" => "Calvin and Hobbes", "author" => "Bill Watterson" );
$collection->insert($obj);

// add another record, with a different "shape"
$obj = array( "title" => "XKCD", "online" => true );
$collection->insert($obj);

// find everything in the collection
$cursor = $collection->find();

// iterate through the results
foreach ($cursor as $obj) {
    echo $obj["title"] . "\n";
}

?>

This would output:

Calvin and Hobbes
XKCD

Making a Connection

To connect to the database server, use one of the following:


<?php

$connection = new Mongo(); // connects to localhost:27017
$connection = new Mongo( "example.com" ); // connect to a remote host (default port: 27017)
$connection = new Mongo( "example.com:65432" ); // connect to a remote host at a given port

?>

You do not have to explicitly disconnect from the database. When $connection goes out of scope, the connection will be closed automatically and any database resources it was using will be freed.

Getting a Database

To select a database, use:


<?php

$db = $connection->dbname;

?>

The database does not need to be created in advance, you can create new databases by selecting them.

Be careful of typos! You can inadvertently create a new database, which can cause confusing errors:


<?php

$db = $connection->mybiglongdbname;
// do some stuff
$db = $connection->mybiglongdbanme;
// now connected to a different database!

?>

Getting A Collection

Getting a collection has the same syntax as getting a database:


<?php

$db = $connection->baz;
$collection = $db->foobar;

// or, more succinctly
$collection = $connection->baz->foobar;

?>

A collection is analogous to a table (if you are familiar with relational databases).

Inserting a Document

Associative arrays are the basic object that can be saved to a collection in the database. A somewhat random "document" might be:


<?php

$doc = array( "name" => "MongoDB",
   "type" => "database",
   "count" => 1,
   "info" => (object)array( "x" => 203, "y" => 102),
   "versions" => array("0.9.7", "0.9.8", "0.9.9")
);

?>

Note that you can have nested arrays and objects.

To insert this document, use MongoCollection::insert():


<?php

$collection->insert( $doc );

?>

Finding Documents using MongoCollection::findOne()

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


<?php

$obj = $collection->findOne();
var_dump( $obj );

?>

This should print:

array(6) {
  ["_id"]=>
  object(MongoId)#8 (1) {
    ["$id"]=>
    string(24) "4e2995576803fab768000000"
  }
  ["name"]=>
  string(7) "MongoDB"
  ["type"]=>
  string(8) "database"
  ["count"]=>
  int(1)
  ["info"]=>
  array(2) {
    ["x"]=>
    int(203)
    ["y"]=>
    int(102)
  }
  ["versions"]=>
  array(3) {
    [0]=>
    string(5) "0.9.7"
    [1]=>
    string(5) "0.9.8"
    [2]=>
    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:


<?php

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

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

?>

Note that these inserts pass a second array: array("safe" => true). This second field specifies options for the insert. By default, the driver does not wait for a database response for writes, so the driver would not catch the the _id. As we specify that this is a "safe" write, the driver will wait for a database response and see that the write did not go through. In general, all writes should use the "safe" option (it is omitted in previous examples for simplicity).

Adding Multiple Documents

In order to do more interesting things with queries, let's add multiple simple documents to the collection. These documents will just be of the form array( "i" => value ); and we can do this fairly efficiently in a loop:


<?php

for($i=0; $i<100; $i++) {
    $collection->insert( array( "i" => $i ) );
}

?>

Notice that we can insert arrays with different key sets into the same collection. This aspect is what we mean when we say that MongoDB is "schema-free".

Counting Documents in A Collection

Now that we've inserted 101 documents (the 100 we did in the loop, plus the first one), we can check to see if we have them all using the MongoCollection::count() method.


<?php

echo $collection->count();

?>

and it should print 101.

Using a Cursor to Get All of the Documents

In order to get all the documents in the collection, we will use MongoCollection::find(). The find() method returns a MongoCursor object which allows us to iterate over the set of documents that matched our query. So to query all of the documents and print them out:


<?php

$cursor = $collection->find();
foreach ($cursor as $id => $value) {
    echo "$id: ";
    var_dump( $value );
}

?>

and that should print all 101 documents in the collection. $id is the _id field of a document (cast to a string) and $value is the document itself.

Setting Criteria for a Query

We can create a query to pass to the MongoCollection::find() method to get a subset of the documents in our collection. For example, if we wanted to find the document for which the value of the "i" field is 71, we would do the following:


<?php

$query = array( "i" => 71 );
$cursor = $collection->find( $query );

while( $cursor->hasNext() ) {
    var_dump( $cursor->getNext() );
}

?>

and it should just print just one document:

array(2) {
  ["_id"]=>
  object(MongoId)#6 (0) {
  }
  ["i"]=>
  int(71)
  ["_ns"]=>
  "testCollection"
}

Getting A Set of Documents With a Query

We can use the query to get a set of documents from our collection. For example, if we wanted to get all documents where "i" > 50, we could write:


<?php

$query = array( "i" => array( '$gt' => 50 ) ); //note the single quotes around '$gt'
$cursor = $coll->find( $query );

while( $cursor->hasNext() ) {
    var_dump( $cursor->getNext() );
}

?>

which should print the documents where i > 50. We could also get a range, say 20 < i <= 30:


<?php

$query = array( "i" => array( "\$gt" => 20, "\$lte" => 30 ) );
$cursor = $coll->find( $query );

while( $cursor->hasNext() ) {
    var_dump( $cursor->getNext() );
}

?>

Remember to always escape the $-symbol or use single quotes. Otherwise PHP will interpret it to be the variable $gt.

Creating An Index

MongoDB supports indexes, and they are very easy to add on a collection. To create an index, you specify the field name and direction: ascending (1) or descending (-1). The following creates an ascending index on the "i" field:


<?php

$coll->ensureIndex( array( "i" => 1 ) );  // create index on "i"
$coll->ensureIndex( array( "i" => -1, "j" => 1 ) );  // index on "i" descending, "j" ascending

?>

Indexing is critical for good read performance as your data grows. If you are not familiar with indexing, check out the MongoCollection::ensureIndex() documentation and the core » MongoDB indexing documentation.

Tutorial

Introduction

Making a Connection

See Also

Getting a Database

See Also

Getting A Collection

See Also

Inserting a Document

See Also

Finding Documents using MongoCollection::findOne()

See Also

Adding Multiple Documents

Counting Documents in A Collection

Using a Cursor to Get All of the Documents

See Also

Setting Criteria for a Query

Getting A Set of Documents With a Query

Creating An Index