to get sum in multiple conditions in mongodb and php - php

Question

I've the following code to get the some of all price that have type 1 or a specific value but it dosen't work.
<?php
$m = new Mongo();
if (!$m)echo "Not Connected to database successfully";
$db =$m->mongo_project;
$collection = $db->prices;
$pipeline=array(
array(
'$match' => array(
'_id' => array(
'$type' =>1
)
)
),
array(
'$group' => array(
'_id' => '',
'count' => array(
'$sum' => '$price'
)
)
),
);
$out = $collection->aggregate($pipeline);
foreach ($out as $key=>$value) {
if($key=='result') {
$r=$value[0]['count'];
}
}
echo $r;?>

Answer 1

I think you mean a document that has a field "type" with a value of 1. The $type operator used here is a special MongoDB operator used to match certain BSON types. In this case you were asking for matching _id fields that were a "DOUBLE" type, or BSON type 1.
Correcting this:
$pipeline=array(
array(
'$match' => array(
'type' => 1
)
),
array(
'$group' => array(
'_id' => '',
'total' => array(
'$sum' => '$price'
)
)
),
);
Or you could just get the "sum" of the "price" values per each "type" value by passing that as the _id in your $group operation, instead. That way you can see everything at a glance:
$pipeline=array(
array(
'$group' => array(
'_id' => '$type',
'total' => array(
'$sum' => '$price'
)
)
),
);
In that context, '$type` means the value of the field.