Question

我正在使用下面的代码注册用户，有一个上传图片的选项，如果为null，则不会注册用户，即可以正常工作，我唯一要面对的就是图片是{ {1}}应该向用户显示警报对话框，但是警报对话框根本不起作用。我应该如何实施警报对话框？

curl -d '{json}' -H 'Content-Type: application/json' https://example.com

Answer 1

您需要使用函数showDialog以便出现对话框：

else {
   print("Please Upload the Image");
     showDialog(
     context: context,
     builder: (BuildContext context) {
         return AlertDialog(
                 title: Text("Image Required"),
                 content: Text("Please upload the image"),
                  actions: <Widget>[
                   FlatButton(
                     child: Text("Close"),
                     onPressed: () {
                      Navigator.of(context).pop();
                      },
                   )
                  ],
                );
               };
             );
           }

Answer 2

Peter Haddad的答案解决了这个问题，但是我建议将AlertDialog放在小部件中，这样很容易再次使用AlertDialog。这是我为项目执行的操作：

Dialogs.dart：

import 'package:flutter/material.dart';

enum alertDialogAction { cancel, save }

class Dialogs {
  static Future<alertDialogAction> alertDialog(
    BuildContext context,
    String title,
    String body,
    String cancel,
    String save,
  ) {
    Future<alertDialogAction> action = showDialog(
        context: context,
        barrierDismissible: true,
        builder: (BuildContext context) {
          return AlertDialog(
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(10),
            ),
            title: Text(title),
            content: Text(body),
            actions: <Widget>[
              FlatButton(
                  onPressed: () =>
                      Navigator.pop(context, alertDialogAction.cancel),
                  child: Text(cancel)),
              RaisedButton(
                  color: Colors.orange,
                  onPressed: () =>
                      Navigator.of(context).pop(alertDialogAction.save),
                  child: Text(
                    save,
                    style: TextStyle(color: Colors.white),
                  )),
            ],
          );
        });
    return (action != null) ? action : alertDialogAction.cancel;
  }

这里是您如何称呼它：

onPressed:() async {
   final action= await Dialogs.alertDialog(context,"Title","Body","Cancel","Save");
   //cancel and save are the button text for cancel and save operation
   if(action==alertDialogAction.save){
     //do something
     Navigator.pop(context);
   }
}

Answer 3

您还可以使用支架显示对话框，例如，

Scaffold.of(context).showSnackBar(SnackBar(content: AlertDialog(content: Text('Alert!!!'))));

但是您必须牢记上下文应该是当前的支架。因此，您可能希望将body属性（在Scaffold中）包装在Builder Widget中，然后在该Builder Widget中使用上下文时，该上下文将是当前的Scaffold。

Answer 4

showDialog(
     context: context,
     builder: (BuildContext context) {
         return AlertDialog(
                 title: Text("Your Title!!!"),
                 content: Text("Your Content!!!"),
                  actions: <Widget>[
                   FlatButton(
                     child: Text("Close"),
                     onPressed: () {
                      Navigator.of(context).pop();
                      },
                   )
                  ],
                );
               };
             );

如何使警报对话框在抖动中工作

4 个答案: