how to add value into firebase field

Question

I'm new to react native and firebase, and trying to create a social media app, building up a adding friend feature.

I'm trying to add UID into the current user's database here is my code :


    const friendadd = async() =>{

        
       // get the users field
        const friendlist = firebase.firestore().collection('users').where("UID", "==", firebase.auth().currentUser.uid).get();

        const addfriend = await friendlist.update({
            "FriendsList.yVHnHIqhsOYbVbWOM6TbjpU4N3x1":true
        })

        
    }
    friendadd()


}

and this is what my firebase looks like

by using the code above, it doesn't update the field somehow. but if I hard code the doc it will work :

const friendlist = firebase.firestore().collection('users').doc('CgQklWWClMJdoOvU4pEk')

how do I get the current user and update the field?

Frank van Puffelen · Accepted Answer · 2021-10-26 03:47:29Z

1

To add an entry to your FriendsList field, you can use an arrayUnion operation:

friendlist.update({
  FriendsList: firebase.firestore.FieldValue.arrayUnion({
    uid: "uidOfItemToAdd",
    bio: "bioOfItemToAdd"
  })
});

Update: This code sets friendlist to a Promise<QuerySnapshot>:

const friendlist = firebase.firestore().collection('users').where("UID", "==", firebase.auth().currentUser.uid).get();

To process these documents and update each of them:

friendlist.then((querySnapshot) => {
  querySnapshot.forEach((doc) => {
    doc.ref.update(...); // 👈 here goes the same code as above
  });
});

edited Oct 26, 2021 at 3:47

answered Oct 26, 2021 at 0:48

Frank van Puffelen

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4 Comments

Chang Over a year ago

Hi Frank, I tried this way, but still didn't update. I'm wondering if its because const friendlist = firebase.firestore().collection('users').where("UID", "==", firebase.auth().currentUser.uid).get(); this line? it didn't get into the doc?

Chang Over a year ago

Because if i hard code the .doc, it will update. const friendlist = firebase.firestore().collection('users').doc('CgQklWWClMJdoOvU4pEk'). how do i get the current document?

Frank van Puffelen Over a year ago

Yeah, that won't work. I updated the code in my answer, but strongly recommend spending some time in the documentation on processing queries: firebase.google.com/docs/firestore/query-data/…, or in the codelab: firebase.google.com/codelabs/firestore-web

Chang Over a year ago

Thank you so much. for the update, is there a way to locate other people's uid? and add it to current users FriendsList?

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