Question

我有以下JSON网址。我正在尝试使用子代码hair []和math []填充我的列表视图，然后从JSON URL获取它们。

以下是网址http://pastebin.com/raw.php?i=2fzqLYXj

阵列内部＆＃34;学生＆＃34;有一个名为＆＃34; Properties＆＃34;和另一个子阵列＆＃34;属性＆＃34;叫＆＃34;成绩＆＃34;。＆＃34;头发＆＃34;在里面＆＃34;属性＆＃34;和＆＃34;数学＆＃34;在里面＆＃34;成绩＆＃34;。

这是我的WebService类

public class WebService
    {
        public WebService ()
        {

        }

        public async Task<Rootobject> GetStudentInfoAsync (string apiurl) {

            var client = new HttpClient (); 

            var response = await client.GetStringAsync(string.Format(apiurl));

            return JsonConvert.DeserializeObject<Rootobject>(response.ToString());

        }
    }

这是我的视图模型

  public class Property
    {

        public int iq { get; set; }
        public string hair { get; set; }
        public string glasses { get; set; }

        public Grade[] Grades { get; set; }

    }
    public class StudentInfo
    {
        public string name { get; set; }
        public string lastname { get; set; }

        public Property[] Properties { get; set; }

        public string StudentName {
            get{ return String.Format ("{0}", name); }
        }
//I am accessing the JSON sub arrays with the following to get the "hair" and "math" properties.

        public string[] HairColors
    {
        get
        {
            return (Properties ?? Enumerable.Empty<Property>()).Select(p => p.hair).ToArray();
        }
    }
       public string[] MathGrades
    {
        get
        {
            return (Properties ?? Enumerable.Empty<Property>()).SelectMany(p => p.Grades ?? Enumerable.Empty<Grade>()).Select(g => g.Math).ToArray();
        }
    }

    }

    public class Rootobject
    {
        public StudentInfo[] students { get; set; }

    }
}

以下是我使用学生姓名填充列表视图的方法。注意＆＃34; StudentName＆＃34;不是在一个子阵列中。

var sv = new WebService();
            var es = await sv.GetStudentInfoAsync(apiurl);
            Xamarin.Forms.Device.BeginInvokeOnMainThread( () => {

                listView.ItemsSource = es.students;
            });
var cell = new DataTemplate (typeof(TextCell));

            listView.ItemTemplate = cell;
            listView.ItemTemplate.SetBinding(TextCell.TextProperty, "StudentName");

但我需要使用HairColors和MathGrades填充我的列表视图，如下所示，但以下代码不起作用。

var sv = new WebService();
            var es = await sv.GetStudentInfoAsync(apiurl);
            Xamarin.Forms.Device.BeginInvokeOnMainThread( () => {

                listView.ItemsSource = es.students;
            });
var cell = new DataTemplate (typeof(TextCell));

            listView.ItemTemplate = cell;
            listView.ItemTemplate.SetBinding(TextCell.TextProperty, "HairColors");
        listView.ItemTemplate.SetBinding (TextCell.DetailProperty, "MathGrades");

这段代码有什么用？我如何使它工作？

Answer 1

您可以为此制作自定义转换器：

public class HairColorsConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        var hairColors = (string[])value;

        return string.Join(", ", hairColors);
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

然后绑定它：

SetBinding(TextCell.TextProperty, "HairColors", BindingMode.Default, new HairColorsConverter());

使用JSON子阵列填充列表视图

1 个答案: