I have this in

[
  {
    "date": "2022-12-03T12:16:52.403Z",
    "configs": [
      {
        "name": "Shubham",
        "values": [
          {
            "text": "172cm",
            "type": "Height",
          },
          {
            "text": "80kg",
            "type": "Weight",
          },
          {
            "text": "male",
            "type": "Gender",
          },
        ],
      }
    ]
  },
  {....},{....}
]

Want to convert config into objects like this

[
  {
    "date": "2022-12-03T12:16:52.403Z",
    "configs": {
       "name": "Shubham",
       "Height": "172cm",
       "Weight": "80kg",
       "Gender": "male",
    }
  },
 {...},{...},
]

I know how to do in Javascript array map method but need to understand how to do in mongoDb query ($project).

CodePudding user response：

Did you try this?

arr=[];
yourOutPutJson.forEach(function(b){var obj={};obj.name=b.configs[0].name;b.configs[0].values.forEach(function(c){obj[c.type]=c.text});arr.push(obj)});

CodePudding user response：

Here is a possible approach

1. First $unwind the configs since it contains only 1 element
2. In the $project stage use $arrayToObject to convert the [{k:'key1',v:'value1'},{k:'key2',v:'value2'}] to {key1:'value1',key2:'value2'}.
3. The $map stage is used to convert the field names in values array to the above format.
4. $concatArrays is used to concat the name field and value before converting array to object so that it becomes [{k:'name',v:'Shubham'},{k:'Height',v:'172cm'}...]

Playground Link

db.collection.aggregate([
  {
    $unwind: "$configs"
  },
  {
    $project: {
      date: 1,
      configs: {
        $arrayToObject: {
          $concatArrays: [
            {
              $map: {
                input: "$configs.values",
                as: "el",
                in: {
                  k: "$$el.type",
                  v: "$$el.text"
                }
              }
            },
            [
              {
                k: "name",
                v: "$configs.name"
              }
            ]
          ]
        },
        
      },
      
    },
    
  },
  
])