How to use Array contains in the same array fields in firebase for flutter-CodePudding

I have a chat collection.

each document has an array with two user id's. my goal is to get the chat that has both user sys id's

I tried running the following but I got an error because we cant use two 'arrayContains' in one query.

Is there any way to perform such query?

here is an image of the data structure

  Future getChat({required List userIdsArr}) async {
    var docId = '';

    userIdsArr.sort((a, b) {
      return a.compareTo(b);
    });
    var filter1 = userIdsArr[0];
    var filter2 = userIdsArr[1];
    await chat
        .where(userIdsArrayColumn, arrayContains: userIdsArr[0])
        .where(userIdsArrayColumn, arrayContains: userIdsArr[1])
        .get()
        .then((value) {
      value.docs.forEach((element) {
        docId = element.id;
      });
    });
    return docId;
  }

the goal is to get the chat that pertains to the users being passed in userIdsArr

CodePudding user response：

this seems to work, is there a better way of doing this?

 Future getChat({required List userIdsArr}) async {
    var docId = '';
    userIdsArr.sort((a, b) {
      return a.compareTo(b);
    });

    await chat
        .where(userIdsArrayColumn, arrayContains: userIdsArr[0])
        // .where(userIdsArrayColumn, arrayContains: userIdsArr[1])
        .get()
        .then((value) {
      value.docs.forEach((element) {
        if (element[userIdsArrayColumn].contains(userIdsArr[1])) {
          log('match found!');
          docId = element.id;
        }
      });
    });
    return docId;
  }

CodePudding user response：

A query can only contain a single array-contains query.

To allow your query, you'll want to add an additional field to the document where you keep the pair of UIDs in a predictable (e.g. alphabetical) order. With such a field you can then use a query such as:

where("concatenated_uids", isEqualTo: userIdsArr[0] "_"  userIdsArr[1])