Laravel MongoDB - aggregation, ordering query

Question

I am wondering how could I achieve a specific result.

Starting of I am using https://github.com/jenssegers/laravel-mongodb

The code sample below is used to get an array of documents that contains my specific slug in the rewards node. And till that point, everything works as intended.

 $array = [
            'rewards.slug' => ['$eq' => 'example_slug'],
            'expired' => ['$gte' => \Carbon\Carbon::now()->toDateTimeString()]
        ];
        $models = Master::raw(function ($collection) use (&$array) {
            return $collection->find(
                $array, ["typeMap" => ['root' => 'array', 'document' => 'array']])
                ->toArray();
        });

My example document

{
    "_id": {
        "$oid": "5be4464eafad20007245543f"
    },
    "some_int_value": 100,
    "some_string_value": "String",
    "rewards": [
        {
            "slug": "example_slug",
            "name": "Example slug",
            "quantity": 4,
            "estimated": {
                "value": 18750
            }
        },
        {
            "slug": "example_slug",
            "name": "Example slug",
            "quantity": 1,
            "estimated": {
                "value": 100
            }
        },
        {
            "slug": "other_example",
            "name": "Other slug example",
            "quantity": 1,
            "estimated": {
                "value": 100
            }
        }
    ],
    "expires": "2018-11-08 20:20:45",
}

Desired result

I would like to implement some more complex query, which would do the following.

• Retrieve documents that : pseudo select all documents that contain reward "slug": "example_slug", sum the quantity of them, return greater than X quantity documents, order by sum quantity desc
• and a very similar one to the above select all documents that contain reward "slug": "example_slug", sum estimated.value, return greater than X estimated.value documents, order by sum of estimated.value desc

If you do need more explanation feel free to ask, I feel like I don't even know where to start with this one.

All help is greatly appreciated

Answer 1

You can use below aggregation in 3.6.

$addFields to create an extra slugcount field to hold the result.

$filter rewards with slug matching example_slug followed by $sum to sum the quantity field.

$match with $gt > X - aggregation expression to filter documents where the sum of all matching quantities is greater than X

$sort slugcount desc and $project with exclusion to remove the slugcount from the final response.

db.colname.aggregate([
{"$addFields":{
  "slugcount":
   {"$let":{
    "vars":{
     "mslug":{
      "$filter":{
       "input":"$rewards",
       "cond":{"$eq":["$$this.slug","example_slug"]}
      }
     }
    },
    "in":{"$sum":"$$mslug.quantity"}
    }}
}}, 
{"$match":{"slugcount":{"$gt":X}}},
{"$sort":{"slugcount":-1}},
{"$project":{"slugcount":0}}
])

Something like

ModelName::raw(function ($collection) {
 return $collection->aggregate([
  ['$match' => ['expired' => ['$gte' => \Carbon\Carbon::now()->toDateTimeString()]]],
  ['$addFields' => [
    'slugcount'
     ['$let' => [
      'vars' => [
       'mslug' => [
        '$filter' => [
         'input' => '$rewards',
         'cond' => ['$eq' => ['$$this.slug','example_slug']]
        ]
       ]
      ],
      'in' => ['$sum' => '$$mslug.quantity']
      ]]
  ]],
  ['$match' => ['slugcount'=> ['$gt' => X]]],
  ['$sort' => ['slugcount' => -1]],
  ['$project' => ['slugcount' => 0]]]);
});

You can replace quantity with estimated.value for second aggregation.