php mongoDB exception: A pipeline stage specification object must contain exactly one field

Question

I have to convert this query from mysql to mongoDB using php

select content_id ,member_id, content_type_id,social_network_id from recent_activty where  content_type_id  = 10  AND social_network_id = 9 order by id desc  group by  content_id  limit 5

I need the result like :

array(2) {
        ["content_id"]=>
        string(6) "122558"
        ["member_id"]=>
        string(6) "180306",
        ["content_type_id"]=>
        string(6) "10",
        ["social_network_id"]=>
        string(6) "9",
      },
      array(2) {
        ["content_id"]=>
        string(6) "122549"
        ["member_id"]=>
        string(6) "180306",
        ["content_type_id"]=>
        string(6) "10",
        ["social_network_id"]=>
        string(6) "9",
      },
      array(2) {
        ["content_id"]=>
        string(6) "122528"
        ["member_id"]=>
        string(6) "180306",
        ["content_type_id"]=>
        string(6) "10",
        ["social_network_id"]=>
        string(6) "9",
      },

I tried Aggregation Framework as

 $result = $collection->aggregate(array(
            '$match' => array('content_type_id'=>"10", "social_network_id"=>"9"),
            '$project' => array('content_type_id'=>1, "social_network_id"=>1, "content_id"=>1),
            '$group' => array('_id' => array('member_id'=>'$member_id')),
            '$sort'  => array('_id'=>-1),
            '$limit' => 5,
        ));

But i got this error

["errmsg"]=>
  string(80) "exception: A pipeline stage specification object must contain exactly one field."

and I tried

$result = $collection->aggregate(array(
                    '$match' => array('content_type_id'=>"10", "social_network_id"=>"9"),
                    '$project' => array("_id"=>'$content_id' ,'content_type_id'=>1),
                    '$group' => array('_id' => array('content_id'=>'$content_id', 'member_id'=>'$member_id')), 
                )
            );

I'm new to mongoDB AND I spent a lot of time to convert this query and to solve this error , any one can help me

Thanks

Answer 1

You can use querymongo.com to convert mysql queries to mongo. For this question your code should be like this.

$result = $collection->aggregate(array(
                array(
                '$match' => array('content_type_id'=>"10", "social_network_id"=>"9"
                )),
                array(
                '$project' => array("_id"=>'$content_id' ,'content_type_id'=>1
                )),
                array(
                '$group' => array('_id' => array('content_id'=>'$content_id', 'member_id'=>'$member_id'))), 
            )
        );

$match , $group (pipeline operators) should be inside array. http://php.net/mongocollection.aggregate