Flutter form builder - FormBuilderImagePicker

Question

I'm letting my users upload an image to my app, from gallery or using the camera. Then the image is stored as a string on SQflite database

FormBuilderImagePicker(
  name: 'photo',
  decoration: InputDecoration(labelText: 'Upload Image'),
  maxImages: 1,
  onSaved:(val){
    try{
      selectedImg = val.first;
      imageBytes = selectedImg.readAsBytesSync(); // convert to bytes
      base64Image = base64Encode(imageBytes); // convert to string
      object.photo = base64Image;
    }catch(e){
      print(e);
    }
  }
),

this code was working fine on flutter_form_builder v3, now after migrating to v4 the value of val never updates to the selected image because i'm getting the following error:

E/flutter (24620): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: NoSuchMethodError: The getter 'iterator' was called on null.
E/flutter (24620): Receiver: null
E/flutter (24620): Tried calling: iterator

E/flutter (24620): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:51:5)
E/flutter (24620): #1      new FormBuilderImagePicker.<anonymous closure>.<anonymous closure>.<anonymous closure>.<anonymous closure> (package:flutter_form_builder/src/fields/form_builder_image_picker.dart:187:58)
E/flutter (24620): #2      _ImageSourceBottomSheetState._onPickImage (package:flutter_form_builder/src/widgets/image_source_sheet.dart:89:33)
E/flutter (24620): <asynchronous suspension>
E/flutter (24620): #3      _ImageSourceBottomSheetState.build.<anonymous closure> (package:flutter_form_builder/src/widgets/image_source_sheet.dart:111:28)
E/flutter (24620): #4      _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:993:19)
E/flutter (24620): #5      _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:1111:38)
E/flutter (24620): #6      GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:183:24)
E/flutter (24620): #7      TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:598:11)
E/flutter (24620): #8      BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:287:5)
E/flutter (24620): #9      BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:259:7)
E/flutter (24620): #10     GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:157:27)
E/flutter (24620): #11     GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:362:20)
E/flutter (24620): #12     GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:338:22)
E/flutter (24620): #13     RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:267:11)
E/flutter (24620): #14     GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:295:7)
E/flutter (24620): #15     GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:240:7)
E/flutter (24620): #16     GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:213:7)
E/flutter (24620): #17     _rootRunUnary (dart:async/zone.dart:1206:13)
E/flutter (24620): #18     _CustomZone.runUnary (dart:async/zone.dart:1100:19)
E/flutter (24620): #19     _CustomZone.runUnaryGuarded (dart:async/zone.dart:1005:7)
E/flutter (24620): #20     _invoke1 (dart:ui/hooks.dart:265:10)
E/flutter (24620): #21     _dispatchPointerDataPacket (dart:ui/hooks.dart:174:5)

i've been trying to debug this for a couple hours now to no success, any help would be appreciated!

Solution

According to the package's Changelog for version [4.2.0] (Dec 29, 2020) (see screenshot), the developers "Removed image picker field from package - moved to a separate form_builder_image_picker package."

If you're in a hurry, a quick option is to use an earlier version of the package, BUT that's not a great long-term solution, so you'll probably want to properly implement the updated versions.

Comments

[Taha Malik]

Are you sure val is not null? Also, Were you able to catch this exception in catch block?

[leshugo33]

in every other form field the value of val gets updated on change without problem, and yes the catch was working as intended but again, on v3 of the package.

[leshugo33]

So I find a way: It seems that now you have to set the FormBuilderImagePicker initialValue: [], for it to work