fix(core): FormBuilder.onChanged during setInternalFieldValue instead of as Form widget attribute. Fixes #960

avoids calling onChanged before internal changes are done

Author: danvick

packages/flutter_form_builder/example/lib/main.dart

@@ -58,6 +58,10 @@ class CompleteFormState extends State<CompleteForm> {
               FormBuilder(
                 key: _formKey,
                 // enabled: false,
+                onChanged: () {
+                  _formKey.currentState!.save();
+                  debugPrint(_formKey.currentState!.value.toString());
+                },
                 autovalidateMode: AutovalidateMode.disabled,
                 initialValue: const {
                   'movie_rating': 5,

packages/flutter_form_builder/lib/src/form_builder.dart

@@ -1,7 +1,6 @@
 import 'dart:developer';
 
 import 'package:flutter/material.dart';
-
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 
 /// A container for form fields.
@@ -126,15 +125,13 @@ class FormBuilderState extends State<FormBuilder> {
         initialValue[name];
   }
 
-  void setInternalFieldValue<T>(
-    String name,
-    T? value, {
-    required bool isSetState,
-  }) {
+  void setInternalFieldValue<T>(String name, T? value,
+      {required bool isSetState}) {
     _instantValue[name] = value;
     if (isSetState) {
       setState(() {});
     }
+    widget.onChanged?.call();
   }
 
   bool get isValid =>
@@ -170,10 +167,7 @@ class FormBuilderState extends State<FormBuilder> {
     field.registerTransformer(_transformers);
     if (oldField != null) {
       // ignore: invalid_use_of_protected_member
-      field.setValue(
-        oldField.value,
-        populateForm: false,
-      );
+      field.setValue(oldField.value, populateForm: false);
     } else {
       // ignore: invalid_use_of_protected_member
       field.setValue(
@@ -263,7 +257,7 @@ class FormBuilderState extends State<FormBuilder> {
       key: _formKey,
       autovalidateMode: widget.autovalidateMode,
       onWillPop: widget.onWillPop,
-      onChanged: widget.onChanged,
+      // `onChanged` is called during setInternalFieldValue else will be called early
       child: FocusTraversalGroup(
         policy: WidgetOrderTraversalPolicy(),
         child: widget.child,

packages/flutter_form_builder/lib/src/form_builder_field.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/material.dart';
-
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 
 enum OptionsOrientation { horizontal, vertical, wrap }
@@ -47,7 +46,7 @@ class FormBuilderField<T> extends FormField<T> {
   /// {@macro flutter.widgets.Focus.focusNode}
   final FocusNode? focusNode;
 
-  //TODO: implement bool autofocus, ValueChanged<bool> onValidated
+  // TODO: implement bool autofocus, ValueChanged<bool> onValidated
 
   /// Creates a single form field.
   const FormBuilderField({
@@ -167,9 +166,7 @@ class FormBuilderFieldState<F extends FormBuilderField<T>, T>
   //   super.save();
   // }
 
-  void _informFormForFieldChange({
-    required bool isSetState,
-  }) {
+  void _informFormForFieldChange({required bool isSetState}) {
     if (_formBuilderState != null) {
       if (enabled || !_formBuilderState!.widget.skipDisabled) {
         _formBuilderState!.setInternalFieldValue<T>(
@@ -196,18 +193,14 @@ class FormBuilderFieldState<F extends FormBuilderField<T>, T>
   void setValue(T? value, {bool populateForm = true}) {
     super.setValue(value);
     if (populateForm) {
-      _informFormForFieldChange(
-        isSetState: false,
-      );
+      _informFormForFieldChange(isSetState: false);
     }
   }
 
   @override
   void didChange(T? value) {
     super.didChange(value);
-    _informFormForFieldChange(
-      isSetState: false,
-    );
+    _informFormForFieldChange(isSetState: false);
     widget.onChanged?.call(value);
   }