Push an object into array if not exists else update the array if exact match not exists

Question

I have a few mongodb documents having an array called states in it. A sample document is given below .

{ "_id":ObjectId("xxxxxxxxxx"),
  "states":[
             {"place":"EU","skId":"SK01"},
             {"place":"IN","skId":"SK05"},
             {"place":"NZ","skId":"SK08"}
           ]
}

If I get a new object I have to push into the states array of the respective document if the 'place' key of new object does not matches those in the array , else in case if the 'place' key of the new object matches with any of the object in array then I have to replace or update that object in array with my new object. I am currently able to insert new objects into array (case 1) but unable to update (case 2).Adding my code and expected output below.

case 1 -->

new object  --> {"place":"KL","skId":"SK08"}
expected output : { "_id":ObjectId("xxxxxxxxxx"),
                    "states":[
                              {"place":"EU","skId":"SK01"},
                              {"place":"IN","skId":"SK05"},
                              {"place":"NZ","skId":"SK08"},
                              {"place":"KL","skId":"SK08"}
                             ]
                   }

case 2 -->

new object  --> {"place":"NZ","skId":"SK01"}
expected output : { "_id":ObjectId("xxxxxxxxxx"),
                    "states":[
                              {"place":"EU","skId":"SK01"},
                              {"place":"IN","skId":"SK05"},
                              {"place":"NZ","skId":"SK01"}
                              
                             ]
                   }

my code :

var query  = {"_id": ObjectId(xxx)}
var arr = [];
db.collection('Regions').find(query).toArray().then((data) => {
   arr = data[0]["states"];
   const index = arr.findIndex((e) => e.place === reqBody.place);
   var obj = {"place":reqBody.place,"skId":reqBody.skId};
        if (index > -1) {
                arr[index] = obj;
                  } else {
                     arr.push(obj);
                          }
   var newStates={"states":arr}
   var newStateValue = {$set:newSquad};
                            
   db.collection("Regions").updateOne(query, newStateValue, function(err, result) {
                                if(err){
                                    resolve({
                                        "error": ""+err+"",
                                        "statuscode": "404"
                                    });
                                }
   })
 })

You can refer to the following question's answer. [Can mongo upsert array data.](https://stackoverflow.com/questions/13588342/can-mongo-upsert-array-data) — Sandeep Bochaliya, Oct 01 '21 at 11:35

score 0 · Answer 1 · answered Oct 11 '21 at 06:19

You can do the followings in an aggregation pipeline:

$match to filter your intented documents
$addFields with $map to conditionally update the matched document in the states array if any array entry matched
$setUnion the result in step 2 with an array of your input document as the insert case for no array entry found
$merge back to the original document to update

Here is the Mongo playground for your reference.

Push an object into array if not exists else update the array if exact match not exists

1 Answers1