CODEWITHSUNDEEP
firebasegoogle-cloud-firestore
user2828442
user2828442

Reputation: 2515

update object in array - Firebase functions

Function executes when a write is made in collection logs, it checks if doc exists in collection totals. If doc exists it is trying to update number object with number+1 at [0] of array.

Here is my code:

...//some code
var washingtonRef = admin.firestore().collection('totals').doc(entryDate_show);
        washingtonRef.get().then((doc: any)=> {
          if (doc.exists) {
            console.log("doc found");
  console.log("Document data:", doc.data());
  washingtonRef.update({
    [auth_ID]: admin.firestore.FieldValue.arrayUnion(
      { number: doc.data().number+1,  // here it is trying to do +1
        fullname: fullname, 
        authid: auth_ID },
      )
  });
...//some code

Problem: It is not working as expected

In array, it is adding new object [1] with number : NaN

Expected behaviour: number : 2 at [0]

Attaching pic of the console:

enter image description here

Upvotes: 0

Views: 410

Answers (1)

Doug Stevenson
Doug Stevenson

Reputation: 317362

FieldValue.arrayUnion() adds a new element to an array field. That's why you're seeing a new object.

Firestore provides no update operation that uses the index of an array item to modify it. If you want to update an item in an array by index, you have to read the document, modify the array in memory, then update the array field back to the document.

Upvotes: 1

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