Flutter Firebase Loop over collection in a document [duplicate]

问题

This question already has an answer here:

Using Flutter Firestore plug in, do something for each sub collection in a document (1 answer)

Closed last year.

I have this path in my Database:

/messages/tT2Q16n1FMZoTNZQOejtWuJdCmD2/ZqihbgR7skcytLAe88fQecmxcIc2-tT2Q16n1FMZoTNZQOejtWuJdCmD2/1579626761580

and from here I have to get content.

I am trying this:

var snapshot = Firestore.instance.collection('messages').document(user.id).snapshots();

but how can I loop over these items and get content from each collection?

And then in my UI I want to print this content message:

              Container(
                child: Text(
                  'Content: ${document['content']}',
                  style: TextStyle(color: primaryColor),
                ),
                alignment: Alignment.centerLeft,
                margin: EdgeInsets.fromLTRB(10.0, 0.0, 0.0, 5.0),
              ),

回答1:

The client-side SDKs for Firestore have no way to request a list of collections. For this reason you'll either need to name your collections in a way that you can embed in your code already, or use one of the Admin SDKs to get a list of collection names and expose that to your client-side code in some way (for example through Cloud Functions).

Also see:

• Fetching all collections in Firestore
• Trying to list collection of Firestore Database
• How to list subcollections in a Cloud Firestore document
• Using Flutter Firestore plug in, do something for each sub collection in a document

来源：https://stackoverflow.com/questions/59850567/flutter-firebase-loop-over-collection-in-a-document