Creating Sub-Collection in Document from Flutter app

Question

I am trying to create a sub-collection in a document and set data to documents in the created sub-collection.

I have tried this but the program crashes every time I run this.

  await Firestore.instance
      .collection('/path')
      .document("documentPath")
      .collection('/subCollectionPath')
      .document()
      .setData({
    'TestData': "Data",
  }).then((onValue) {
    print('Created it in sub collection');
  }).catchError((e) {
    print('======Error======== ' + e);
  });

I have also looked online but I cannot find any documentation for it.

Any ideas?

When I try the above code, the app crashes with the following message

   flutter: EVENT StorageTaskEventType.success
   *** First throw call stack:
   (
    0   CoreFoundation                      0x0000000111eb61bb __exceptionPreprocess + 331
    1   libobjc.A.dylib                     0x0000000111454735 objc_exception_throw + 48
    2   Runner                              0x000000010ce707b1 -[FIRFirestore documentWithPath:] + 257
    3   Runner                              0x000000010d10662c getDocumentReference + 124
    4   Runner                              0x000000010d109879 -[FLTCloudFirestorePlugin handleMethodCall:result:] + 2665
    5   Flutter                             0x000000010e5b99a2 __45-[FlutterMethodChannel setMethodCallHandler:]_block_invoke + 115
    6   Flutter                             0x000000010e5d6616 _ZNK5shell21PlatformMessageRouter21HandlePlatformMessageEN3fml6RefPtrIN5blink15PlatformMessageEEE + 166
    7<…>

Lost connection to device.

Answer 1

 final databaseReference = Firestore.instance;
databaseReference.collection('main collection name').document( unique id).collection('string name').document().setData(); // your answer missing **.document()**  before setData

this is the right Syntex