How to push data into a nested array in firestore?

Question

How can i do this? I have a data stucture for each user in a user collection, I have created my own schema for the user object stored in the collection.

I want to have a favoriteMovies collection initalised into this object so that i can add movie objects inside.

Heres an example of what im trying to do :


      async function signUp(email, password){
        const {user} = await auth.createUserWithEmailAndPassword(email, password)
        
        // initialise the schema for the data
        const userInitialised = await db.collection('users').doc(user.uid).set(userSchemaObject(user.uid))
        return userInitialised;
    
        
      }

Then the schema so far:


    export default function userSchemaObject(uuid){
      return {
        uuid,
        favmovies:[]
      }
    }

What exactly is your problem? It is not clear to me. Can you give more details on what does not work as expected? Note that you cannot create an “empty collection”. A collection is created with the first document. I suspect that you mix up collection and field of type array. Again, can you give more details on the expected result and what does not work. — Renaud Tarnec
– Renaud Tarnec, Commented Dec 24, 2020 at 9:13

Renaud Tarnec · Accepted Answer · 2021-06-07 19:52:29Z

2

I'm asking how to push data to a nested array

From your question and comment, your favmovies field should be of type Array and does not seem to be "nested". Therefore you should simply use arrayUnion() in order to push data to this Array.

The following code demonstrates how to create a doc with an empty Array field, then, later, how to push a value.

const db = firebase.firestore();

const newDocRef = db.collection('test').doc();

newDocRef
    .set({
      uuid: 'uuid_value',
      favmovies: [],
    })
    .then(() => {
      newDocRef.update({
        favmovies: firebase.firestore.FieldValue.arrayUnion('movie1'),
      });
    });

Note that you can pass several elements to the arrayUnion() method.

newDocRef.update({
    favmovies: firebase.firestore.FieldValue.arrayUnion(
      'movie1',
      'movie2'
    ),
});

edited Jun 7, 2021 at 19:52

answered Dec 24, 2020 at 10:32

Renaud Tarnec

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2 Comments

Shamoon Over a year ago

What about pushing objects?

Renaud Tarnec Over a year ago

Pushing objects into the array or adding new elements to a map (i.e. a set of key value pairs)?

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