Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
118 views
in Technique[技术] by (71.8m points)

android - Dart Function returns null

I have a function which calls request to create a new Student in server

createStudents(String studentName) async {
await Webservice()
    .postReq(new API().createNewStudent(context), studentName)
    .then((value) {
  if (value is Students) {
    Students std = value;
    helper.initializeDatabase();
    helper.insertStudents(std);
    return "Sucessfull";
  } else {
    return value;
  }
});

}

in this example i sent name of student and new student is created in server.

if succesfull it returns a student object.

and if not succesfull then message is returned.

i debugged and checked value in this function but it always return null.

when sucessful it returns Student object but createStudents function returns null. same for error message

var ab = await createTags(data);
                  print(ab);

ab is always null.

i dont know why it always returns null.

question from:https://stackoverflow.com/questions/66060843/dart-function-returns-null

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

I am not 100% sure, but my best guess is that you forgot "return" statement

createStudents(String studentName) async {
    //Here should be return
    final value = await Webservice()
        .postReq(new API().createNewStudent(context), studentName);
        
      if (value is Students) {
        Students std = value;
        helper.initializeDatabase();
        helper.insertStudents(std);
        return "Sucessfull";
      } else {
        return value;
      }
 }

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...