Querying a specific document from subcollection using firestore and flutter

Question

what i am trying to do is query a specific document using the 'Document ID'. however the query comes up null. here is my code.

 void getEquipDetail() async {
    await _firestore
        .collection('users')
        .document(_userUid)
        .collection('equipment')
        .document(documentID)
        .get()
        .then((DocumentSnapshot ds) {
      equipName = ds.data['equip_name'];
      print(equipName);
    });
  }

this works fine when i had 'equipment' as a root-level collection, but since making it a subcollection of 'users' i cannot query a specific document.

here is the db structure currently -collection (users) * root level -document (userid) -collection(equipment) -document (equipment documents) * this is what im trying to query

here is the error being returned

[VERBOSE-2:ui_dart_state.cc(148)] Unhandled Exception: NoSuchMethodError: The method '[]' was called on null.
Receiver: null
Tried calling: []("equip_name")
#0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
#1      _EquipmentDetailScreenState.getEquipDetail.<anonymous closure> (package:simmanager/screens/equip_detail_screen.dart:52:26)
#2      _rootRunUnary (dart:async/zone.dart:1132:38)
#3      _CustomZone.runUnary (dart:async/zone.dart:1029:19)
#4      _FutureListener.handleValue (dart:async/future_impl.dart:137:18)
#5      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:678:45)
#6      Future._propagateToListeners (dart:async/future_impl.dart:707:32)
#7      Future._completeWithValue (dart:async/future_impl.dart:522:5)
#8      _AsyncAwaitCompleter.complete (dart:async-patch/async_patch.dart:30:15)
#9      _completeOnAsyncReturn (dart:async-patch/async_patch.dart:288:13)
#10     DocumentReference.get (package:cloud_firestore/src/document_reference.da<…>

this is the code that works without any issue (its for items instead of equipment)

void getItemDetail() async {
    await Firestore.instance
        .collection('items')
        .document(widget.item.document)
        .get()
        .then((DocumentSnapshot snapshot) {
      itemDetails = snapshot.data;
      itemName = snapshot['item_name'];
      itemNum = snapshot['item_num'.toString()];
      itemDesc = snapshot['item_desc'];
      itemLoc = snapshot['item_location'];
      itemQty = snapshot['item_qty'.toString()];
      itemUom = snapshot['item_uom'];
      itemMfr = snapshot['item_mfr'];
      itemStock = snapshot['out_of_stock'];
      lastEditDate = snapshot['edit_date'];
      createDate = snapshot['create_date'];
      imageURL = snapshot['image_url'];

What's the problem? What exactly isn't working the way you expect? Your code doesn't seem to be checking if the document actually exists. Maybe it doesn't. — Doug Stevenson
the issue is that this is returning a null. i have verified the document exists (i check and print the userid and document id prior to running this function. im only running into this issue when querying a document nested under 2 collections. — David Escobar
What exactly is returning null? Please be specific about what you're observing. Please also share code that does not "return null" by whatever observation you're making. — Doug Stevenson

Doug Stevenson Doug Stevenson · Accepted Answer · 2019-11-13T05:32:24

Your code in the first example doesn't really match the code in the second example. Please compare them carefully. For the first example, it looks like you meant to say:

equipName = ds['equip_name'];

Querying a specific document from subcollection using firestore and flutter

1 Answers