问题描述
我有一个 json 文件，其中包含 Covid 引起的病例和死亡的国家和详细信息。我在 MainPage 中有我的列表视图，其中成功列出了国家/地区。现在，我希望在用户点击一个国家后显示每个国家的详细信息。
这里是 Region.cs
using System;
using System.Collections.Generic;
using System.Text;
namespace just4jsonCLOSE.Models
{
// Root myDeserializedClass = JsonConvert.DeserializeObject<Root>(myJsonResponse);
public class RegionData
{
public string country { get; set; }
public int totalCases { get; set; }
public int newCases { get; set; }
public int totalDeaths { get; set; }
public int newDeaths { get; set; }
public int totalRecovered { get; set; }
public int activeCases { get; set; }
public int serIoUsCritical { get; set; }
public int casesPerMil { get; set; }
public double deathsPerMil { get; set; }
public int totalTests { get; set; }
public int testsPerMil { get; set; }
public int population { get; set; }
}
public class RegionList
{
public List<RegionData> regionData { get; set; }
}
}
我的 MainPage.xaml.cs
namespace just4jsonCLOSE
{
[XamlCompilation(XamlCompilationoptions.Compile)]
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
GetJsonData();
}
void GetJsonData()
{
string jsonFileName = "region.json";
RegionList ObjContactList = new RegionList();
var assembly = typeof(MainPage).GetTypeInfo().Assembly;
Stream stream = assembly.GetManifestResourceStream($"{assembly.GetName().Name}.{jsonFileName}");
using (var reader = new System.IO.StreamReader(stream))
{
var jsonString = reader.ReadToEnd();
//Converting JSON Array Objects into generic list
ObjContactList = JsonConvert.DeserializeObject<RegionList>(jsonString);
}
//Binding listview with json string
listviewRegions.ItemsSource = ObjContactList.regionData;
}
}
}
我的 MainPage.xaml（我已经评论了除 1st :country 之外的所有绑定标签）
<Grid>
<Grid>
<Grid.RowDeFinitions>
<RowDeFinition Height="Auto"/>
<RowDeFinition Height="*"/>
</Grid.RowDeFinitions>
<Label Grid.Row="0" Margin="30" Text="Details per country about COVID" FontSize="25" />
<ListView x:Name="listviewRegions" Grid.Row="1" HorizontalOptions="FillAndExpand" Footer="" HasUnevenRows="True">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid HorizontalOptions="FillAndExpand" Padding="10">
<Grid.RowDeFinitions>
<RowDeFinition Height="Auto"/>
<RowDeFinition Height="Auto"/>
<RowDeFinition Height="Auto"/>
<RowDeFinition Height="Auto"/>
</Grid.RowDeFinitions>
<Label Text="{Binding country}" HorizontalOptions="StartAndExpand" Grid.Row="0" TextColor="Black" FontAttributes="Bold" />
<!-- <Label Text="{Binding totalCases}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding newCases}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding totalDeaths}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding newDeaths}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding totalRecovered}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding activeCases}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding serIoUsCritical}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding casesPerMil}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding deathsPerMil}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding totalTests}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding testsPerMil}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/>
<Label Text="{Binding population}" HorizontalOptions="StartAndExpand" Grid.Row="1" TextColor="Orange" FontAttributes="Bold"/> -->
<BoxView HeightRequest="2" Margin="0,10,0" BackgroundColor="Gray" Grid.Row="3" HorizontalOptions="FillAndExpand" />
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</Grid>
</Grid>
最后是我的 region.json 文件（小部分）
{
"regionData": [
{
"country": "World","totalCases": 157341642,"newCases": 651328,"totalDeaths": 3278509,"newDeaths": 9126,"totalRecovered": 135480211,"activeCases": 18582922,"serIoUsCritical": 108879,"casesPerMil": 20185,"deathsPerMil": 420.6,"totalTests": 0,"testsPerMil": 0,"population": 0
},{
"country": "Europe","totalCases": 45325498,"newCases": 111518,"totalDeaths": 1031121,"newDeaths": 2579,"totalRecovered": 40490614,"activeCases": 3803763,"serIoUsCritical": 27087,"casesPerMil": 0,"deathsPerMil": 0,{
"country": "Asia","totalCases": 42985197,"newCases": 499649,"totalDeaths": 558151,"newDeaths": 5628,"totalRecovered": 36953518,"activeCases": 5473528,"serIoUsCritical": 33491,"population": 0
}
]
}
解决方法
首先，将 ItemTapped 处理程序添加到您的 ListView
<ListView x:Name="listviewRegions" ItemTapped="RegionTapped" ...
然后在您的代码隐藏中
protected void RegionTapped(object sender,ItemTappedEventArgs e)
{
// cast the tapped item to the correct type
var region = (RegionData)e.Item;
Navigation.PushAsync(new DetailPage(region));
}
要使其工作，您必须在 NavigtionPage 中分配 MainPage 时使用 App.xaml.cs
MainPage = new NavigationPage(new MainPage());
最后，您需要创建一个新的 XAML 页面 DetailPage，它接受 RegionData 作为构造函数中的参数。然后，您可以使用数据绑定将 XAML 中的 UI 绑定到 RegionData 实例
public DetailPage(RegionData data)
{
InitializeComponent();
this.BindingContext = data;
}