Flutter - remove a firebase document onTap()

Question

I have a ListView, filled with Firebase collection as chat messages.

When the user long press a ListTile (an item on the list), I show a BottomSheet.

When the user clicks the Delete button on the BottomSheet, the document should be removed. I'm unable to find a way to remove the selected document after tapping the "Delete" button.

The listview widget:

return ListView.builder(
    padding: new EdgeInsets.all(8.0),
    reverse: true,
    itemCount: snapshot.data.documents.length,
    itemBuilder: (_, int index) {
    var message = snapshot.data.documents[index]["content"];
    var from = snapshot.data.documents[index]["idFrom"];
    return new ListTile(
        leading: new CircleAvatar(
            backgroundColor: Colors.blue,
            child: new Image.network(
                "http://res.cloudinary.com/kennyy/image/upload/v1531317427/avatar_z1rc6f.png")),
        title: new Row(
        children: <Widget>[
            new Expanded(child: new Text(message))
        ]
        ),
        subtitle: new Text(from),
        onLongPress: () {
        showModalBottomSheet<void>(context: context,
            builder: (BuildContext context) {
                return Container(
                    child: new Wrap(
                    children: <Widget>[
                        new ListTile(
                        leading: new Icon(Icons.delete),
                        title: new Text('Delete'),
                        onTap: () =>
                                          // Remove the tapped document here - how?
                                          print(snapshot.data.documents[index]["id"])
                                          Firestore.instance.collection("chats").document("ROOM_1")
                                          .collection("messages").document(snapshot.data.documents[index]["id"])
                                          .delete();
                                      )
                        )
                    ]
                    )
                );
            });
        }
    );
});

I need to find a way to remove the document in the onTap() method. not sure why, but even when I do:

 onTap: () => {
     // Remove the tapped document here - how?
     const id = snapshot.data.documents[index]["id"];
 },

the IDE retruns an error Expected an identifier

Answer 1

To delete a document, we can use the runTransaction method of the Firestore.instance and use the delete method of the Transaction class.

await Firestore.instance.runTransaction((Transaction myTransaction) async {
    await myTransaction.delete(snapshot.data.documents[index].reference);
});

instead of

Firestore.instance.collection("chats").document("ROOM_1")  
    .collection("messages").document(snapshot.data.documents[index]["id"])
    .delete();

Here is the look of my dummy database before the deletion of doc1 document:

After deleting doc1:

Answer 2

If you know document id, You can delete easily.

  Future<void> rejectJob(String jobId){
    return _db.collection('jobs').document(jobId).delete();
  }