windows phone 绑定数据

Question

我是 Windows Phone 的初学者。请帮助我：-

这是我从服务中提取的类：-

public class Answer
{
    public string answerId { get; set; }
    public string answer { get; set; }
}

public class Question
{
    public string questionId { get; set; }
    public string questionTitle { get; set; }
    public string storyUrl { get; set; }
    public string correctAnswerId { get; set; }
    public List<Answer> answers { get; set; }
}

public class RootObject
{
    public string response { get; set; }
    public string message { get; set; }
    public string questionType { get; set; }
    public string device_id { get; set; }
    public string quiz_type { get; set; }
    public int totalQuestion { get; set; }
    public List<Question> questions { get; set; }

}

现在，借助此功能，我想将问题绑定在文本块中，并将选项绑定在单选按钮中。 我做了以下编码来反序列化 json:-

WebClient wc = new WebClient();
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
wc.DownloadStringAsync(new Uri("my service url"));

我使用这个方法：wc_DownloadStringCompleted()

并写下这段代码

  var rootObject = JsonConvert.DeserializeObject<RootObject>(e.Result);

        val = rootObject.device_id;

        Question ques = new Question
        {
            questionTitle = rootObject.questions.Last().questionTitle,
            answers = rootObject.questions.Last().answers.Select(ans => new Answer { answer = ans.answer, answerId = ans.answerId }).ToList(),
            questionId = rootObject.questions.Last().questionId,
            storyUrl = rootObject.questions.Last().storyUrl,
            correctAnswerId = rootObject.questions.Last().correctAnswerId

        };
        txtQuestion.DataContext = ques.questionTitle;
        rb1.Content = ques.answers.ElementAt(0).answer;
        rb2.Content = ques.answers.ElementAt(1).answer;
        rb3.Content = ques.answers.ElementAt(2).answer;
        rb4.Content = ques.answers.ElementAt(3).answer;

这就是我从服务中得到最后一个问题的方式

我的页面场景是：- 在提交按钮上点击正确的答案将显示&一个按钮“下一步”可见以显示下一个问题。

请帮我解决这个问题.....

Answer 1

你可以试试这个方法：

声明Question 类型的变量来保存当前显示的问题的索引：

private int CurrentQuestionIndex;

声明集合变量（如果您打算稍后使用数据绑定，请使用 ObservableCollection 而不是 List）来保存来自 Web 服务的所有问题：

public List<Question> Questions { get; set; }

下载json字符串完成后，将CurrentQuestion设置为第一个问题，并将所有问题存储在Questions中：

var rootObject = JsonConvert.DeserializeObject<RootObject>(e.Result);
val = rootObject.device_id;
//store all questions
Questions = rootObject.questions;

DisplayCurrentQuestion();

重构您的代码以将问题显示为一个函数 (DisplayCurrentQuestion())，以便我们可以重用它来显示下一个问题：

private void DisplayCurrentQuestion()
{
    Question ques = Questions[CurrentQuestionIndex];
    txtQuestion.Text = ques.questionTitle;
    rb1.Content = ques.answers[0]answer;
    rb2.Content = ques.answers[1].answer;
    rb3.Content = ques.answers[2].answer;
    rb4.Content = ques.answers[3].answer;
}

单击“下一步”按钮只需将CurrentQuestionIndex 更改为下一个问题并显示它：

CurrentQuestionIndex++;
if(CurrentQuestionIndex > Questions.Count)
{
    //this is the last question, no next question available
}
else DisplayCurrentQuestion();

“我们如何在“提交”按钮上获得正确的AnswerId 和 answerId”。

你可以这样得到：

Question ques = Questions[CurrentQuestionIndex];
var correctAnswerId = ques.correctAnswerId;

if(rb1.IsChecked && ques.answers(0).answerId == correctAnswerId)
{
    //selected answer is correct answer
}
//else check next radio button
else if(rb2.IsChecked && ques.answers(1).answerId == correctAnswerId)
{
    //selected answer is correct answer
}
....
....

请注意，还有另一种方法可以对数据绑定和遵循 MVVM 模式执行相同操作，因此请考虑更改标题，因为您当前的代码未使用数据绑定，而此答案也未使用数据绑定。