I have my firebase app working with React whereby I sign users up and then log there information to the database. I am creating a "dating app" and I would like some way to store empty arrays. e.g, matchers: [] etc

I tried something liket this:

firebase.database().ref('users/' + userId).set({
      id: userId,
      username: name,
      email: email,
      matchers: [],
      likedUsers: [],
      disLikedUsers: []
    });

but then read that firebase doesn't really handle arrays as such and now am not sure how to do this. I want the empty array so then when the user starts using the app they can add to their various arrays.

any ideas?

I have my firebase app working with React whereby I sign users up and then log there information to the database. I am creating a "dating app" and I would like some way to store empty arrays. e.g, matchers: [] etc

I tried something liket this:

firebase.database().ref('users/' + userId).set({
      id: userId,
      username: name,
      email: email,
      matchers: [],
      likedUsers: [],
      disLikedUsers: []
    });

but then read that firebase doesn't really handle arrays as such and now am not sure how to do this. I want the empty array so then when the user starts using the app they can add to their various arrays.

any ideas?

• javascript
• arrays
• reactjs
• firebase
• firebase-realtime-database

• You can store arrays in the FireStore database if it's okay with your project requirements. I suppose you also could store the arrays as subcollections in the FireStore. – Kim Commented Jan 26, 2018 at 13:22
• @Kim cheers Kim! this looks good to me – The Walrus Commented Jan 26, 2018 at 13:28

2 Answers 2

Firebase has always remended against using arrays. Instead of re-iterating the reasons, I'll point you to the blog post Best Practices: Arrays in Firebase.

But your bigger problem seems to be having empty arrays: the . If a property doesn't have a value, the Firebase Database doesn't store that property. That means that an empty array is not stored in the database and thus not read back.

You'll have to re-create those properties yourself after you read the data back. If you're having problems with this, update your question to show how you read the data.

You don't need to create those fields, they are initialized with the first item and the remended way to indexed collections is to use the push and later to map it to an array.