How to reference Firestore documentID in a Flutter FutureBuilder - flutter

Question

I have working code that gets a collection ('songs') from Firestore using a Future and a QuerySnapshot. I have that in a small function getSongs(). While I'm inside that function I have access to the documents' IDs ... so if I call say:
print(songsQuery.documents[1].documentID);
I get -LSvpZxM2pUIYjjp0qby
But later in my code I use a FutureBuilder where I call getSongs() for the future: and then build out a ListView with tiles of song info (Artist, Title, etc) from the snapshot in the builder:.
While I'm now in this widget I can't seem to figure out how to reference my .documentID anymore. I can get to all the .data elements for each document...but not the actual documentID.
Is there something very obvious that I'm missing?
Thanks for any help.
ER
I have scoured the internet trying to resolve with no luck. It seems like many people take the list of documents, load them into an array, add the doc.id, push it all into an array of items. Then use items. I would like to just use the snapshots as rendered back from Firestore and reference the doc.id directly if possible.
import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import 'dart:async';
class AllSongs extends StatelessWidget {
Future getSongs() async {
var firestore = Firestore.instance;
QuerySnapshot songsQuery = await firestore.collection('songs').getDocuments();
print(songsQuery.documents[1].documentID);
//Here I can get to documentID...
return songsQuery.documents;
}
#override
Widget build(BuildContext context) {
return Center(
child: FutureBuilder(
future: getSongs(),
builder: (_, songSnapshots){
print('How do I reference the DocumentID in here?');
print(songSnapshots.data.length);
print(songSnapshots.data[0].data['title']);
//print(songSnapshots.data[0].documentID);
//print(songSnapshots.data[0].ref);
//print(songSnapshots.data[0].data[ DOCUMENTID?? ]);
if(songSnapshots.connectionState == ConnectionState.waiting){
return Center(
child: Text('Loading...'),
);
} else {
return ListView.builder(
itemCount: songSnapshots.data.length ,
itemBuilder: (_, index){
return ListTile(
title: Text(songSnapshots.data[index].data['title']),
subtitle: Text(songSnapshots.data[index].data['artist']),
);
});
}
},
)
);
}
}

Answer 1

You're trying to access the value the value of the future before it resolves.
Try adding this line:
if (!songSnapshots.hasData) {
// Future hasn't resolved
return something;
}
// Future has resolved, you can access your data (including documentId)
Your future resolves to a list of DocumentSnapshot so just wait for the future to resolve and you should have access to all your data. Alternatively, you can try to access this inside your else statement where the state of the connection is not waiting, but in this case you are considering any non-waiting states as successful so I'd recommend using the hasData property of the AsyncSnapshot class instead.