Multiple widgets using the same GlobalKey

[SGarno]

I am trying to wrap the form builder in a routine which generates the form dynamically from a set of form field descriptors, but am getting the above error.

Here is the code:

import 'package:flutter/material.dart';
import 'package:flutter_form_builder/flutter_form_builder.dart';
import 'package:testflutter/model/FormItem.dart';

import '../types.dart';

class FormGenerator extends StatelessWidget {

  final Key key;
  final List<FormItem> formItems;

  FormGenerator({this.key, this.formItems});

  Widget _buildTextField( FormItem item ) {
    return FormBuilderTextField(
      attribute: item.name,
      decoration: InputDecoration(labelText: item.title),
      validators: [
      ],
    );   
  }

  Widget _buildRadioField( FormItem item ) {
    return Text("...coming soon ...");      
  }

  Widget _buildColorPicker( FormItem item ) {
    return Text("...coming soon ...");      
  }

  Widget _buildSwitch( FormItem item ) {
    return Text("...coming soon ...");      
  }

  Widget _buildCheckbox( FormItem item ) {
    return Text("...coming soon ...");      
  }

  List<Widget> _buildForm( ) {

    List<Widget> widgetList = new List<Widget>();

    for (var count = 0; count < this.formItems.length; count++) {
      FormItem field = this.formItems[count];

      switch( field.type ) {
        case FieldType.input:
        case FieldType.password:
        case FieldType.email:
        case FieldType.numeric:
        case FieldType.textarea: 
          widgetList.add( _buildTextField(field) );
          break;
        case FieldType.radiobutton: 
          widgetList.add( _buildRadioField(field) );
          break;
        case FieldType.color:
          widgetList.add( _buildColorPicker(field) );
          break;
        case FieldType.toggle:
          widgetList.add( _buildSwitch(field) );
          break;
        case FieldType.checkbox:
          widgetList.add( _buildCheckbox(field) );
          break;
      }

    }
    return widgetList;
  }


  @override
  Widget build( BuildContext context ) {

    return FormBuilder(
      key: key,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: _buildForm(),
      )
    );
  }
}

The key is being generated in the parent class outside of the build function.

What am I missing/doing wrong?

[SGarno]

I found a fix, but am not sure I understand why. By renaming the field from key to fbKey, it all worked. I am only passing that value to FormBuilder, so not sure why that would make a difference?

[danvick]

FormBuilder works well with a GlobalKey, this allows you to have a handle on its state. Also, note that your field attribute names (i.e. item.name) should not be the same. If at all there are duplicates that error will be thrown.

[akreienbring]

Hi, I also face this error with the FormBuilder used in two different stateful widgets.

Declared like in the example:

class MyState1 extends State<MyState1Route>{
final GlobalKey<FormBuilderState> _fbKeyForm1 = GlobalKey<FormBuilderState>();

class MyState2 extends State<MyState2Route>{
final GlobalKey<FormBuilderState> _fbKeyForm2 = GlobalKey<FormBuilderState>();

This immediately gives me an error:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following assertion was thrown while finalizing the widget tree:
Multiple widgets used the same GlobalKey.

The proposals from this Stackoverview question did not help.
https://stackoverflow.com/questions/49862572/multiple-widgets-used-the-same-globalkey

I don't think that this is related to flutter_form_builder. Looks like GlobalKey is considered to be the same by flutter.

Anyway, I wanted to let you know and maybe you found a solution for this or know what I'm doing wrong..

[akreienbring]

Ok, forget about it. I accidentally was INDEED using the key twice!