ArgumentError（无效参数：“ TextEditingController”的实例）

Question

请帮助。.我正在尝试制作更新数据页面，但是此错误在此行中出现..

Firestore.instance.collection('reg').add({'name':controllerName}) 

代码如下：

import 'package:flutter/material.dart';
import 'package:cloud_firestore/cloud_firestore.dart';


class EditList extends StatefulWidget {

  @override
  _EditListState createState() => _EditListState();
}

class _EditListState extends State<EditList> {
TextEditingController controllerName;


@override
void initState() { 
  controllerName = new TextEditingController();
  super.initState();

}
  var name;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      appBar: AppBar(
        title: Text('Registration'),
        backgroundColor: Colors.blue,
      ),
      body: Container(
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(30.0),
          child: Column(
            children: <Widget>[
              Padding(
                padding: const EdgeInsets.only(top: 20.0),
              ),
              Text('GROUP'),
              TextField(
                controller: controllerName,
                  onChanged: (String str) {
                    setState(() {
                      name= str;
                    });
                  },
                  decoration: InputDecoration(
                    labelText: 'Name',
                  )),
              //paste here
              const SizedBox(height: 30),
              RaisedButton(
                onPressed: () {
                  if (controllerName.text.isNotEmpty) {
                    Firestore.instance.collection('reg').add({'name':controllerName}) 
                    .then((result){
                      Navigator.pop(context);
                      controllerName.clear();
                    }).catchError((err) =>print(err));
                  }
                },
                child: const Text('Submit', style: TextStyle(fontSize: 20)),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Answer 1

此行：

2

应替换为：

Firestore.instance.collection('reg').add({'name':controllerName})

此外，您可能应该给Firestore.instance.collection('reg').add({'name':controllerName.text}) 一个空字符串的初始值，以使其不能为空。