I can't insert my data inside my database even when I have already used controller. It still shows this error
The following _CastError was thrown while handling a gesture: Null check operator used on a null value
Here is my code:
import 'package:flutter/material.dart';
import 'package:testerlogin/models/flowerbook.dart';
import 'package:testerlogin/models/user.dart';
import '../common_widgets/buttons.dart';
import 'package:flutter_form_builder/flutter_form_builder.dart';
import '../common_widgets/checkbox.dart';
class FormPage extends StatefulWidget {
const FormPage({Key? key, required this.user}) : super(key: key);
final User user;
@override
State<FormPage> createState() => _FormPageState();
}
class _FormPageState extends State<FormPage> {
final GlobalKey<FormBuilderState> _formKey = GlobalKey<FormBuilderState>();
String selectedValue = 'Bouquet';
final dateController = TextEditingController();
final checkboxController = TextEditingController();
final dropdownController = TextEditingController();
final TextStyle labelStyle = const TextStyle(
fontFamily: 'Poppins',
fontWeight: FontWeight.w500,
);
final TextStyle inputStyle = const TextStyle(
fontFamily: 'Poppins',
fontWeight: FontWeight.w600,
);
@override
Widget build(BuildContext context) {
double screenWidth = MediaQuery.of(context).size.width;
return Scaffold(
body: SingleChildScrollView(
child: Form(
key: _formKey,
child: SafeArea(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
//Spacing
const SizedBox(
height: 25,
),
//Back Button
Container(
height: 50,
padding: const EdgeInsets.fromLTRB(2 * 16, 0, 2 * 16, 0),
width: double.infinity,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
IconButton(
onPressed: () {
Navigator.pop(context);
},
icon: const Icon(Icons.arrow_back),
),
],
),
),
const SizedBox(
height: 25,
),
SizedBox(
width: screenWidth,
child: Padding(
padding:
const EdgeInsets.fromLTRB(3 * 16, 0, 3 * 16, 3 * 16),
child: Column(
children: [
//Checkbox
FormField(builder: (FormFieldState state) {
return InputDecorator(
decoration: InputDecoration(
labelText: "Delivery Date",
labelStyle: labelStyle,
errorText: state.errorText,
border: const OutlineInputBorder(),
floatingLabelBehavior:
FloatingLabelBehavior.always,
),
child: FormBuilderDateTimePicker(
controller: dateController,
name: "delivery_date",
));
}),
const SizedBox(height: 25),
FormField(
builder: (FormFieldState state) {
return InputDecorator(
decoration: InputDecoration(
labelText: "Flower Type",
labelStyle: labelStyle,
errorText: state.errorText,
border: const OutlineInputBorder(),
floatingLabelBehavior:
FloatingLabelBehavior.always,
),
child: Column(
children: <Widget>[
checkItemBuilder(context, "Roses",
checkboxController: checkboxController),
checkItemBuilder(context, "Tulips",
checkboxController: checkboxController),
checkItemBuilder(context, "Carnation",
checkboxController: checkboxController),
checkItemBuilder(context, "Daisies",
checkboxController: checkboxController),
checkItemBuilder(context, "Tulips",
checkboxController: checkboxController),
],
),
);
},
),
const SizedBox(height: 25),
SizedBox(
width: MediaQuery.of(context).size.width,
child: FormField(
builder: (FormFieldState state) {
return InputDecorator(
decoration: InputDecoration(
labelText: "Arrangement",
labelStyle: labelStyle,
errorText: state.errorText,
border: const OutlineInputBorder(),
floatingLabelBehavior:
FloatingLabelBehavior.always,
),
child: DropdownButton<String>(
value: selectedValue,
isExpanded: true,
onChanged: (String? newValue) {
setState(() {
selectedValue = newValue ?? 'Bouquet';
dropdownController.text = selectedValue;
});
},
items: <String>[
'Bouquet',
'Vase',
'Box',
'Basket'
].map<DropdownMenuItem<String>>(
(String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
);
},
),
),
const SizedBox(height: 25),
//Submit Button
ButtonGradient(
label: 'Submit',
textStyle: const TextStyle(
fontFamily: 'Poppins',
fontWeight: FontWeight.w600,
color: Colors.white,
),
borderRadius: 50,
gradientColor: const [
Colors.purpleAccent,
Colors.deepPurple,
],
onPressed: () {
if (_formKey.currentState!.validate()) {
Flowerbook flowerbook = Flowerbook(
deliver_date: dateController.text,
flower_type: checkboxController.text,
arrangement: dropdownController.text,
user_id: widget.user.user_id,
);
Flowerbook.register(flowerbook);
}
},
),
],
),
),
),
],
),
),
),
),
);
}
}
I think something is wrong around here:
onPressed: () {
if (_formKey.currentState!.validate()) {
Flowerbook flowerbook = Flowerbook(
deliver_date: dateController.text,
flower_type: checkboxController.text,
arrangement: dropdownController.text,
user_id: widget.user.user_id,
);
Flowerbook.register(flowerbook);
}
But it could also be at the widgets
Here is the error:
The following _CastError was thrown while handling a gesture:
Null check operator used on a null value
When the exception was thrown, this was the stack:
#0 _FormPageState.build.<anonymous closure> (package:testerlogin/pages/formpage.dart:187:54)
#1 _InkResponseState.handleTap (package:flutter/src/material/ink_well.dart:1072:21)
#2 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:253:24)
#3 TapGestureRecognizer.handleTapUp (package:flutter/src/gestures/tap.dart:627:11)
#4 BaseTapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:306:5)
#5 BaseTapGestureRecognizer.acceptGesture (package:flutter/src/gestures/tap.dart:276:7)
#6 GestureArenaManager.sweep (package:flutter/src/gestures/arena.dart:163:27)
#7 GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:464:20)
#8 GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:440:22)
#9 RendererBinding.dispatchEvent (package:flutter/src/rendering/binding.dart:337:11)
#10 GestureBinding._handlePointerEventImmediately (package:flutter/src/gestures/binding.dart:395:7)
#11 GestureBinding.handlePointerEvent (package:flutter/src/gestures/binding.dart:357:5)
#12 GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:314:7)
#13 GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:295:7)
#14 _invoke1 (dart:ui/hooks.dart:167:13)
#15 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:341:7)
#16 _dispatchPointerDataPacket (dart:ui/hooks.dart:94:31)
Handler: "onTap"
Recognizer:
TapGestureRecognizer#75718
That cannot be possible because all of the values are already inside the controller.
I tried printing out the data when I pressed submit button. But it still shows the same error, it didn't even print out the values inside the controller. So, I have removed the code. And tried other ways to fix this.
The code should insert the values to the database after the user have filled in the form.
CodePudding user response：
as mentioned inthe error, on line 187
if (_formKey.currentState!.validate()) {
you're using currentState! (Null Check Operator) when (evidently) currentState is null.
I dont know why, but you can confirm by checking this, and handling the null case accordingly, or checking the rest of the code to see why it is null in this case.
CodePudding user response：
You should change the Form widget that is a child of SingleChildScrollView to FormBuilder.
check README on flutter_form_builder package