'$project' not working in my mongo aggregate query - mongodb-query

Question

This is my Documentation format
{
"_id" : ObjectId("5af56909b8be3925cf199924"),
"pid" : "9354496457",
"vid" : NumberLong("34756636617"),
"title" : "Ascolour Barnard Stripe Tank Tee-(5032)",
"handle" : "ascolour-barnard-stripe-tank-tee-5032",
"image" : "https://cdn.shopify.com/s/files/1/1919/3401/products/5032_barnard_stripe_tank_natural_black_5.jpg?v=1493879380",
"color" : "XL",
"size" : "NATURAL/BLACK",
"width" : null,
"activity" : "",
"brand" : "Ascolour",
"style" : "",
"feature" : "",
"type" : "Adult Singlets",
"price" : 1100,
"compare_at_price" : 1100,
"qty" : 1,
"sku" : "5032",
"visible" : 1
}
{
"_id" : ObjectId("5af56909b8be3925cf199925"),
"pid" : "9354496457",
"vid" : NumberLong("34756636681"),
"title" : "Ascolour Barnard Stripe Tank Tee-(5032)",
"handle" : "ascolour-barnard-stripe-tank-tee-5032",
"image" : "https://cdn.shopify.com/s/files/1/1919/3401/products/5032_barnard_stripe_tank_natural_black_5.jpg?v=1493879380",
"color" : "2XL",
"size" : "NATURAL/BLACK",
"width" : null,
"activity" : "",
"brand" : "Ascolour",
"style" : "",
"feature" : "",
"type" : "Adult Singlets",
"price" : 1100,
"compare_at_price" : 1100,
"qty" : 1,
"sku" : "5032",
"visible" : 1
}
here i search "type"=>"adult Singlets" with distinct "pid" and project all columns in the documents
so i write query:
$cursor = $songs->aggregate([
['$project' => ['_id' => 1, 'title' => 1, 'size' => 1]],
['$match' =>
['$and' => [
['$or' => [
['title' => $regex],
['size' => $regex],
['color' => $regex],
['brand' => $regex],
['activity' => $regex],
['style' => $regex],
['type' => $regex],
['feature' => $regex],
['width' => $regex],
]
],
['visible' => ['$eq' => 1]],
['qty' => ['$gt' => 0]],
]
]
],
['$group' => ["_id" => '$pid']],
['$limit' => 10]
]);
but its not show me anything and if i remove this line
['$project' => ['_id' => 1, 'title' => 1, 'size' => 1]]
then its show me all distinct pid. but i need to show all column w.r.t distinct pid
Thanks in advance :)

Answer 1

by this query i solved it
$cursor = $songs->aggregate([
['$match' =>
['$and' => [
['$or' => [
['title' => $regex],
['size' => $regex],
['color' => $regex],
['brand' => $regex],
['activity' => $regex],
['style' => $regex],
['type' => $regex],
['feature' => $regex],
['width' => $regex],
]
],
['visible' => ['$eq' => 1]],
['qty' => ['$gt' => 0]],
]
]
],
['$group' =>
['_id' => '$pid',
'originalId' => ['$first' => '$_id'],
'title' => ['$first' => '$title'],
'brand' => ['$first' => '$brand'],
'pid' => ['$first' => '$pid'],
'image' => ['$first' => '$image'],
'size' => ['$first' => '$size'],
'color' => ['$first' => '$color'],
'activity' => ['$first' => '$activity'],
'style' => ['$first' => '$style'],
'type' => ['$first' => '$type'],
'feature' => ['$first' => '$feature'],
'width' => ['$first' => '$width'],
'handle' => ['$first' => '$handle'],
'sku' => ['$first' => '$sku'],
'visible' => ['$first' => '$visible'],
'qty' => ['$first' => '$qty'],
'compare_at_price' => ['$first' => '$compare_at_price'],
]
],
['$project' => [
'_id' => '$pid',
'title' => 1,
'brand' => 1,
'pid' => 1,
'image' => 1,
'size' => 1,
'color' => 1,
'activity' => 1,
'style' => 1,
'type' => 1,
'feature' => 1,
'width' => 1,
'handle' => 1,
'image' => 1,
'pid' => '$_id',
'sku' => 1,
'visible' => 1,
'qty' => 1,
'compare_at_price' => 1,
]
],
['$limit' => 10]
]);