（Flutter，Firebase）提交之前进行表单验证

时间：2018-11-26 11:46:06

标签： flutter

我有一个表单，该表单正在提交到Firebase实时数据库，但是无法正确验证该表单。我需要检查用户提交的值是否为null，如果为null，则不应提交，否则，请成功提交。我还想知道如何找出用于电子邮件验证的正则表达式，因为我很快也会将其添加到表单中。

class FF extends StatefulWidget {
  @override
  HomeState createState() => HomeState();
}

class HomeState extends State<FF> {
  List<Item> items = List();
  Item item;
  DatabaseReference itemRef;

  final GlobalKey<FormState> formKey = GlobalKey<FormState>();

  @override
  void initState() {
    super.initState();
    item = Item("", "");
    final FirebaseDatabase database = FirebaseDatabase
        .instance; //Rather then just writing FirebaseDatabase(), get the instance.
    itemRef = database.reference().child('items');
    itemRef.onChildAdded.listen(_onEntryAdded);
    itemRef.onChildChanged.listen(_onEntryChanged);
  }

  _onEntryAdded(Event event) {
    setState(() {
      items.add(Item.fromSnapshot(event.snapshot));
    });
  }

  _onEntryChanged(Event event) {
    var old = items.singleWhere((entry) {
      return entry.key == event.snapshot.key;
    });
    setState(() {
      items[items.indexOf(old)] = Item.fromSnapshot(event.snapshot);
    });
  }

  void handleSubmit() {
    final FormState form = formKey.currentState;

    if (form.validate() == true) {
      form.save();
      form.reset();
      itemRef.push().set(item.toJson());
      Flushbar(
        flushbarPosition: FlushbarPosition.TOP, //Immutable
      )
        ..title = "Thank you for submitting."
        ..message = ""
        ..duration = Duration(seconds: 3)
        ..show(context);
    } else {
//      form.save();
//      form.reset();
//      itemRef.push().set(item.toJson());
      Flushbar(
        flushbarPosition: FlushbarPosition.TOP, //Immutable
      )
        ..title = "Please enter valid data before submitting"
        ..message = ""
        ..duration = Duration(seconds: 3)
        ..show(context);
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Feedback and Enquiry'),
      ),
      resizeToAvoidBottomPadding: false,
      body: new Container(
        decoration: new BoxDecoration(
          image: new DecorationImage(
            image: new AssetImage('images/affedbackground.png'),
            // Background Image
            fit: BoxFit.cover,
          ),
        ),
        child: Column(
          children: <Widget>[
            Flexible(
              flex: 0,
              child: Center(
                child: Form(
                  key: formKey,
                  child: Flex(
                    direction: Axis.vertical,
                    children: <Widget>[
                      ListTile(
                        leading: Text('Subject'),
                        title: TextFormField(
//                          initialValue: '',
                          onSaved: (val) => item.title = val,
                          validator: (val) => val == "" ? val : null,
                        ),
                      ),
                      ListTile(
                        //leading: Icon(Icons.info),
                        leading: Text('Description'),
                        title: TextFormField(
//                          initialValue: '',
                          onSaved: (val) => item.body = val,
                          validator: (val) => val == "" ? val : null,
                        ),
                      ),
                      IconButton(
                        icon: Icon(Icons.send),
                        onPressed: () {
                          handleSubmit();
                        },
                      ),
                    ],
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class Item {
  String key;
  String title;
  String body;

  Item(this.title, this.body);

  Item.fromSnapshot(DataSnapshot snapshot)
      : key = snapshot.key,
        title = snapshot.value["title"],
        body = snapshot.value["body"];

  toJson() {
    return {
      "title": title,
      "body": body,
    };
  }
}

2 个答案:

答案 0 :(得分：0)

经过一番修补，我自己设法做到了，这可能不是解决问题的最优雅的方法，但现在可以完成工作。

添加此内容以检查值：

String _validateData(String value) {
    if (value.isEmpty) {
      // The form is empty
      return "Please enter data";
    }
}

替换为：

validator: (val) => val == "" ? val : null,

使用：

validator: _validateData,

答案 1 :(得分：0)

  

我也想知道如何找出用于电子邮件验证的正则表达式，因为我很快也会将其添加到表单中。

在http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html中找到了用于电子邮件验证的正则表达式的最小大小。短于该长度的任何内容都会拒绝完全有效的电子邮件地址。例如，我看到的大多数邮件都拒绝fred&barney@stonehenge.com，这不仅是有效的电子邮件地址，而且我在那里设置了自动回复程序来证明这一点。 （继续尝试！）。

如果您不想使用那么长的时间，只需检查字符串中是否有@。这几乎是唯一的其他可能性。

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