c# - 在 WinRT 中返回 null 的嵌套 JSON 数组

Question

我正在尝试将 WebApi 应用程序与 Windows RT 应用程序连接起来。我从页面正确接收 Json。我从 JSON 数组异步获取所有元素唯一的问题是嵌套数组返回 null 但是当我调试 json 字符串内部有元素

这里是 MVC 4 和 WinRT 的图像和代码

StudentCollection.cs

private async  void GetStudents() {
            HttpClient client = new HttpClient();
            HttpResponseMessage response = await client.GetAsync(new Uri("http://localhost:17775/api/Students"));
            var json = await response.Content.ReadAsStringAsync();

            var jsarray = JsonArray.Parse(json);


                GetStudentsbyJson(jsarray);
        }
        private  void GetStudentsbyJson(JsonArray result)
        {


            foreach( var item in result)
            {
                Student student = new Student();
                Course course ;
                var obj = item.GetObject();
                foreach (var key in obj.Keys) 
                {
                    IJsonValue value;
                    if(!obj.TryGetValue(key,out value))
                        continue;

                    switch (key)
                    {
                        case "ID":
                            student.ID = Int32.Parse(value.GetNumber().ToString());
                            break;
                        case "Name":
                            student.Name = value.GetString();
                            break;
                        case "Age":
                            student.Age = Int32.Parse(value.GetNumber().ToString());
                            break;
                        case "HasScholarship":
                            student.HasScholarship = value.GetBoolean();
                            break;
                        case "Course":

                            course= GetCourseJson( value.GetObject());

                            break;
                        case "Sex":
                            student.Sex = value.GetString();

                            break;
                    }
                }
                if (student != null)
                    _students.Add(student);
            }

        }

        private Course GetCourseJson(JsonObject jsonObject)
        {

            var course = new Course();
            foreach (var key in jsonObject.Keys)
            {
                IJsonValue value;
                if (!jsonObject.TryGetValue("keys", out value))
                    continue;
                switch (key) { 
                    case "CourseId":
                        course.CourseId = Int32.Parse(value.ToString());
                        break;

                    case "Name":
                        course.Name = value.GetString();
                        if (course.Name == null)
                            throw new NullReferenceException("No Name added");
                        break;

                }
            }
            return course != null ? course : new Course() {Name="Contabilidade" };
        }

主页.xaml

<GridView ItemsSource="{Binding Students}" SelectedIndex="{Binding SelectedStudent, Mode=TwoWay}" Padding="24">
            <GridView.Background>
                <ImageBrush/>
            </GridView.Background>
            <GridView.ItemTemplate>
                <DataTemplate >
                    <Grid Width="200" Height="150">
                        <Grid.Background>
                            <SolidColorBrush Color="Gold"/>
                        </Grid.Background>
                        <StackPanel Orientation="Horizontal" VerticalAlignment="Bottom">
                            <StackPanel.Background>
                                <SolidColorBrush Color="Red" Opacity=".3" />
                            </StackPanel.Background>
                            <TextBlock Text="{Binding Name}" Padding="12,0,12,0"/>
                            <TextBlock Text="{Binding Course.Name}" />
                            <TextBlock Text="{Binding Age}"/>

                        </StackPanel>
                    </Grid>
                </DataTemplate>
            </GridView.ItemTemplate>
        </GridView> 

[{"Course":{"CourseId":1,"Name":"Engenharia Informatica"},"ID":1,"Name":"Oldemiro","Age":20,"Sex":"male","HasScholarship":true},{"Course":{"CourseId":1,"Name":"Engenharia Informatica"},"ID":2,"Name":"Teotonio","Age":20,"Sex":"male","HasScholarship":false},{"Course":{"CourseId":1,"Name":"Engenharia Informatica"},"ID":3,"Name":"Ivan Ernesto","Age":21,"Sex":"male","HasScholarship":true},{"Course":{"CourseId":1,"Name":"Engenharia Informatica"},"ID":4,"Name":"Severino Mateus","Age":20,"Sex":"male","HasScholarship":true}]

Answer 1

我会做的有点不同。

首先从 NuGet 添加 json.net

然后将这两个类添加到您的项目中：

public class Course
{
    public int CourseId { get; set; }
    public string Name { get; set; }
}

public class Student
{
    public Course Course { get; set; }
    public int ID { get; set; }
    public string Name { get; set; }
    public int Age { get; set; }
    public string Sex { get; set; }
    public bool HasScholarship { get; set; }
}

现在解析看起来像这样

HttpClient client = new HttpClient();
HttpResponseMessage response = await client.GetAsync(new Uri("http://localhost:17775/api/Students"));
var json = await response.Content.ReadAsStringAsync();
var Students = JsonConvert.DeserializeObject<ObservableCollection<Student>>(json);