Question

我从服务器获取一个int Id，该服务器在HTTP请求中波动，可以，并且我想将此值保存在变量中，但是当我调用返回的值时，我得到了这个错误'Future'的实例，有什么建议吗？这是代码

                    child: RaisedButton(onPressed:() {
                    CurrentPrjId= SaveProject();
                    print("CurrentPrjId Is saved CurrentPrjId :::::::: " );
                    print(CurrentPrjId);
                    Navigator.of(context).pushReplacementNamed('/AllUSerStories');
                }
//Save Project

  Future SaveProject() async {

//SaveProjectResult has the id of the current created project which i need that for its user stories
var SaveProjectResult = await GetPostProjects().createProject(_ProjectnameController.text, _CustomernameController.text, _dropNewItem, _dropNewItem2, _StartDateController.text, _EndDateController.text,);
print(":::::::::::::::::::::::::::::::The Project Is Created And Here Its ID In SaveProject:::::::::");
print(SaveProjectResult);
return SaveProjectResult;

}

Answer 1

没有代码，很难猜测，这是怎么回事。但是您可以尝试等待将来的完成。

methOdThatLoadsId().then((id) => print("Id that was loaded: $id"));

或

var id = await methodThatLoadsId();

祝你好运：）

Answer 2

对不起，您的答复很晚。不幸的是，您将等待添加到了错误的位置。尝试这样的事情：

                   child: RaisedButton(onPressed:() async {
                    CurrentPrjId=  await SaveProject();
                    print("CurrentPrjId Is saved CurrentPrjId :::::::: " );
                    print(CurrentPrjId);
                    Navigator.of(context).pushReplacementNamed('/AllUSerStories');
                }
//Save Project

  Future SaveProject() async {

//SaveProjectResult has the id of the current created project which i need that for its user stories
var SaveProjectResult = await GetPostProjects().createProject(_ProjectnameController.text, _CustomernameController.text, _dropNewItem, _dropNewItem2, _StartDateController.text, _EndDateController.text,);
print(":::::::::::::::::::::::::::::::The Project Is Created And Here Its ID In SaveProject:::::::::");
print(SaveProjectResult);
return SaveProjectResult;

或更短：

                   child: RaisedButton(onPressed:() async {
                    CurrentPrjId=  await GetPostProjects().createProject(_ProjectnameController.text, _CustomernameController.text, _dropNewItem, _dropNewItem2, _StartDateController.text, _EndDateController.text,);
                    print("CurrentPrjId Is saved CurrentPrjId :::::::: " );
                    print(CurrentPrjId);
                    Navigator.of(context).pushReplacementNamed('/AllUSerStories');
                }

Answer 3

您必须使用FutureBuilder小部件从异步调用中获取Future值。

CurrentPrjId=FutureBuilder<String>(
    future: SaveProject(),
    builder: (context, snapshot) {
      if (snapshot.hasData) return Text(snapshot.data);
      else if (snapshot.hasError) return Text(snapshot.error);
      return return Text("Await for data");
    },
  );

Flutter中“ Future <dynamic>”的实例

3 个答案: