I want to show "No posts" text when database don't have any posts (length = 0) (Database's post type is list)

When I use this code, it shows error

Error here :

════════ Exception caught by widgets library ═══════════════════════════════════

Class '_JsonQuerySnapshot' has no instance method '[]'.
Receiver: Instance of '_JsonQuerySnapshot'
Tried calling: []("posts")

My code here:

return StreamBuilder(
        stream: FirebaseFirestore.instance
            .collection("users")
            // .orderBy('datePublished', descending: true)
            .snapshots(),
        builder: (context, AsyncSnapshot snapshot) {
          if (snapshot.hasData) {
            if (snapshot.data['posts'].length != 0) {
              return showWidget();
            } else {
              return Container(
                child: Center(child: Text("No posts")),
              );
            }
          } else {
            return const Center(
              child: CircularProgressIndicator(color: Colors.red),
            );
          }
        });

CodePudding user response：

you're trying to get snapshots for a whole collection with :

   FirebaseFirestore.instance
        .collection("users")
        .snapshots(),

this will return a QuerySnapshot which will contain the docs list, so you need to iterate over them to check:

return StreamBuilder<QuerySnapshot>(
    stream: FirebaseFirestore.instance
        .collection("users")
        // .orderBy('datePublished', descending: true)
        .snapshots(),
    builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
      if (snapshot.hasData) {
        final isCollectionEmpty = snapshot.data!.docs.isEmpty;
        final DocumentsWhichContainsPosts = snapshot.data!.docs.where((doc) => (doc.data() as Map<String, dynamic>)["posts"].isNotEmpty);
        if (DocumentsWhichContainsPosts.isNotEmpty) {
          return showWidget();
        } else {
          return Container(
            child: Center(child: Text("No posts")),
          );
        }
      } else {
        return const Center(
          child: CircularProgressIndicator(color: Colors.red),
        );
      }
    });