CODEWITHSUNDEEP
mongodbmongodb-query
yavg
yavg

Reputation: 3051

Add an element to an array, if it exists don't add it, if it exists update it

I am making a voting system in which an object will have an array called scores, every time it is qualified a record will be entered to this array as long as the same id does not exist.

Sample Doc :

{
 name:"jose luis",
 scores:[]
}

The user push :

{id:1,stars:5}

Updated Doc :

{
 name:"jose luis",
 scores:[{id:1,stars:5}]
}

The user push 2nd time :

{id:1,stars:4}

Updated Doc :

{
 name:"jose luis",
 scores:[{id:1,stars:4}]
}  //this should update the value of the stars under the array element with the existing id.

I have tried this :

   Politico.update(
        { name: "jose luis" },
        {
            $setOnInsert: { "$scores.id": body.req.id},
            "$addToSet": {
                scores: {
                    "id": body.req.id,
                    "starts": body.req.stars
                }
            }


        },
        { upsert: true }

I have tried this but it doesn't work, how can I fix it? Thanks a lot.

Upvotes: 1

Views: 494

Answers (1)

whoami - fakeFaceTrueSoul
whoami - fakeFaceTrueSoul

Reputation: 17915

On MongoDB 4.2 or above as you can use aggregation-pipeline in updates, try below query :

Politico.updateOne(
  { name: "jose luis" },
  [{
    $addFields: {
      scores: {
        $reduce: {
          input: "$scores",
          initialValue: [{ id: 1, stars: 5 }], // Input
          in: {
            $cond: [
              { $in: ["$$this.id", "$$value.id"] }, /** Check id exists in 'scores' array */
              "$$value", /** If YES, return input */
              { $concatArrays: ["$$value", ["$$this"]] }/** If NO, concat value(holding array) with current object as array */
            ]
          }
        }
      }
    }
  }]);

You might not need { upsert: true } as you're not writing a new document with name : "jose Luis" & respective scores array. But if you wanted to do that :

Politico.updateOne(
  { name: "jose luis" },
  [{
    $addFields: {
      scores: {
        $reduce: {
          input: "$scores",
          initialValue: [{ id: 1, stars: 5 }], // Input
          in: {
            $cond: [
              { $in: ["$$this.id", "$$value.id"] }, /** Check id exists in 'scores' array */
              "$$value", /** If YES, return input */
              { $concatArrays: ["$$value", ["$$this"]] }/** If NO, concat value(holding array) with current object as array */
            ]
          }
        }
      }
    }
  },
  {$addFields : {scores : { $ifNull: [ "$scores", {id : 13, stars: 3} ] }}} /** This additional 'addFields' will add 'scores' array with input object to newly created doc */
],{upsert : true});

Test : MongoDB-Playground

Upvotes: 1

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