Firestore 不监听查询 (Flutter)

Question

I'm trying to listen to document changes with the following code: (Flutter)

   Firestore.instance
        .collection('myCollection')
        .where("owners.${myUserID}", isEqualTo: true)
        .orderBy("lastRef", descending: true)
        .snapshots()
        .listen((data) {
      print("listening");
      data.documentChanges.forEach((change) {
        setState(() {
          myList = data.documents;
        });
      });
    });

This code only works once, it adds all the right documents to the list, but when a document is updated, it doens't do anything...

I tried this code (without the where query)

   Firestore.instance
        .collection('myCollection')
        .orderBy("lastRef", descending: true)
        .snapshots()
        .listen((data) {
      print("listening");
      data.documentChanges.forEach((change) {
        setState(() {
          myList = data.documents;
        });
      });
    });

Works perfectly, even when a document is updated

I thought I'd had to make an index, but i didn't see any message in the console. Tried creating one manually.

Indexed fields: owners (array), lastRef (descending)

What am I doing wrong?

Thanks in advance!

Answer 1

That data.documentChanges.forEach((change) { around the setState call looks suspicious to me. As far as I can see you should set the documents to the state, whenever your listener gets called.

So something like:

Firestore.instance
    .collection('myCollection')
    .where("owners.${myUserID}", isEqualTo: true)
    .orderBy("lastRef", descending: true)
    .snapshots()
    .listen((data) {
  setState(() {
    myList = data.documents;
  });
});

I doubt it'll change the problem with your query, but I'd recommend changing this either way as it simplifies your listener and makes it more idiomatic.