PHP and MongoDB: Using multiple '$or'

Question

I'm trying to convert this query into an array, so i can use in PHP, but i'm stuck with the 'index' problem... As you can see, i need multiples '$or', because each '$or' validates a set of fields, and i can't join them all in the same '$or'.

Here is the query object:

{
'$and' : [
      { '$or' : [
          {'author' : { '$exists' : false } }
        , {'author' : { '$in' : [ 'john' , false ] } }
    ] }
    , {'$or' : [
          { '$and' : [ { 'type' : 'post' } , { 'user_id' : 123456 } ] }
        , { 'type' : 'comment' }
    ] }
    , { '$or' : [
          { 'tags.name' : { '$in' : [ 'tag1' , 'tag2' ] } }
        , { 'tags' : false }
        , { 'tags' : { '$exists' : false } }
    ] }
]
}

The first set of '$or' validates the 'author' field, so i'm searching any document with 'john' or false in the field, and i want the documents that doesn't have the 'author' field. The second set validates the 'type' field, where i need the documents that have 'comment' as value or 'post' AND the 'user_id' is 123456. The third set validates the 'tags' field, where i need some 'tags.name' inside an '$in' or 'tags' = false or 'tags' doesn't exists...

These 3 sets must be true, that's why they're all in the '$and' operator... I'm aware that '$and' works only in 2.0+, but i'm using 2.1 (aggregation frawework testing... it just ROCKS! XD)

I think that's it... if there's another way of writing the query i would reeeally like to see... thanks!

This query will always do a full collection scan because you're using {$exists:false}. This will be slow To rewrite the query to be more efficient, you'll need to change your schema. — William Z
– William Z, Commented Jul 27, 2012 at 17:05

William Z · Accepted Answer · 2012-07-26 20:56:56Z

5

Here is your query in PHP

$conn = new Mongo("localhost:$port");
$db = $conn->test;
$collection = $db->tb;

$or1 = 
    array( '$or' => array(
            array( 'author' => array( '$exists' => false ) ) ,
            array( 'author' => array( '$in' => array('john', false) ) ) 
          ));

$or2 = 
    array( '$or' => array(
        array( '$and' => 
                array( 
                    array( 'type' => 'post') ,
                    array( 'userid' => 123456 )
                    )
            ),
            array( 'type' => 'comment') 
        ));

$or3 = 
    array( '$or' => array(
            array( 'tags.name' => array( '$in' => array('tag1', 'tag2') ) ) ,
            array( 'tags' => false ), 
            array( 'tags' => array( '$exists' => false ) ) 
        ));

$query = array( '$and' => array( $or1, $or2, $or3 ) );


$cursor = $collection->find($query);
foreach( $cursor as $doc ) {
    // do something
}

answered Jul 26, 2012 at 20:56

William Z

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2 Comments

Vinicius Lima Over a year ago

That reeeealy makes sense!! Thanks!!

Bilbonic Over a year ago

This was exactly what I was looking for. I was trying to create it all in one array and it was getting ugly. Thanks so much!

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