[英]Xamarin Forms - DataTemplate from Nested Property within DataTemplate from Parent Object
我有 3 個名為 Users、Cards 和 BindingUser 的類,這是一個將它們綁定在一起的類。
public class User
{
public int Uid { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class CardData
{
public int _id { get; set; }
public string CardName { get; set; }
public string CardNote { get; set; }
}
public class BindingUser
{
public User bUser { get; set; }
public ObservableCollection<CardData> cardDatas { get; set; }
public BindingUser()
{
cardDatas = new ObservableCollection<CardData>();
}
}
我正在嘗試創建一個水平堆棧布局,為每個用戶填充框架,並且在每個框架中都有屬於該用戶的卡片列表。
我嘗試過使用列表視圖、堆棧布局和谷歌顯示的幾乎所有其他方法來做到這一點,但每個方法都有相同的結果。
我得到了用戶的框架,但它們沒有被填充。
我的xaml
看起來像這樣,我知道這是錯誤的,但我將其格式化為這樣以顯示我想要實現的目標。 在此示例中, FirstName
和LastName
工作正常,但未填充列表視圖。
<ContentPage.Content>
<StackLayout Orientation="Horizontal" BackgroundColor="#EBEBEB" HeightRequest="130" BindableLayout.ItemsSource="{Binding bindingUsers}" WidthRequest="410">
<BindableLayout.ItemTemplate>
<DataTemplate>
<StackLayout HeightRequest="300" VerticalOptions="Start" Orientation="Vertical">
<Frame CornerRadius="0"
HorizontalOptions="Start"
VerticalOptions="Start"
Margin="0"
Padding="0"
WidthRequest="410"
HeightRequest="80"
BackgroundColor="Red"
HasShadow="true">
<StackLayout Orientation="Vertical">
<Label Text="{Binding bUser.FirstName}"/>
<Label Text="{Binding bUser.LastName}"/>
</StackLayout>
</Frame>
<StackLayout Orientation="Vertical" BackgroundColor="Blue">
<ListView BindableLayout.ItemsSource="{Binding bindingUsers.cardDatas}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text ="{Binding CardName}"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</StackLayout>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
</ContentPage.Content>
有人可以指出我正在努力實現的正確方向嗎?
在.net forms
這是一項如此簡單的任務,我需要幾分鍾才能完成,但這讓我感到沮喪。
在這里你考慮了兩件事,
第一個,對於列表視圖,您必須使用 ItemsSource 屬性而不是 BindableLayout.ItemsSource。
第二個是模板的 BindingContext 將是可綁定布局源的單個項目。 例如,在您的情況下 CardData。 因此,您嘗試綁定到 ListView 的源代碼不是 CardData 的一部分。 因此,當您在數據模板內綁定不同的對象時,您已將 BindingContext 關鍵字(如 BindingContext.YourProperty)與源引用進行了綁定。 參考下面的代碼,
<StackLayout x:Name="baseLayout" Orientation="Horizontal" BackgroundColor="#EBEBEB" HeightRequest="130"
BindableLayout.ItemsSource="{Binding cardDatas}" WidthRequest="410">
<BindableLayout.ItemTemplate>
<DataTemplate>
<StackLayout HeightRequest="300" VerticalOptions="Start" Orientation="Vertical">
<Frame CornerRadius="0"
HorizontalOptions="Start"
VerticalOptions="Start"
Margin="0"
Padding="0"
WidthRequest="410"
HeightRequest="80"
BackgroundColor="Red"
HasShadow="true">
<StackLayout Orientation="Vertical">
<Label Text="{Binding BindingContext.bUser.FirstName, Source={x:Reference baseLayout}}"/>
<Label Text="{Binding BindingContext.bUser.LastName, Source={x:Reference baseLayout}}"/>
</StackLayout>
</Frame>
<StackLayout Orientation="Vertical" BackgroundColor="Blue">
<ListView ItemsSource="{Binding BindingContext.cardDatas, Source={x:Reference baseLayout}}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text ="{Binding CardName}"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</StackLayout>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
以及基於您的代碼的模型和視圖模型類,
public class User
{
public int Uid { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class CardData
{
public int _id { get; set; }
public string CardName { get; set; }
public string CardNote { get; set; }
}
public class BindingUser
{
public User bUser { get; set; }
public ObservableCollection<CardData> cardDatas { get; set; }
public BindingUser()
{
cardDatas = new ObservableCollection<CardData>()
{
new CardData()
{
_id = 1,
CardName = "Testing1",
CardNote = "Test data1",
},
new CardData()
{
_id = 2,
CardName = "Testing2",
CardNote = "Test data2",
},
new CardData()
{
_id = 3,
CardName = "Testing3",
CardNote = "Test data3",
},
};
bUser = new User
{
Uid = 23432,
FirstName = "First User",
LastName = "Last User",
};
}
}
如果要綁定復雜數據,最好使用MVVM模型,視圖模型可幫助您更清晰地了解視圖和模型,我對代碼進行了一些更改,希望對您有所幫助:
XAML:
<StackLayout BindableLayout.ItemsSource="{Binding Data}"
Orientation="Horizontal" BackgroundColor="#EBEBEB">
<BindableLayout.ItemTemplate>
<DataTemplate>
<StackLayout>
<Frame CornerRadius="0"
HorizontalOptions="Start"
VerticalOptions="Start"
Margin="0"
Padding="0"
WidthRequest="410"
BackgroundColor="Red"
HasShadow="true">
<StackLayout Orientation="Vertical">
<Label Text="{Binding FirstName}"/>
<Label Text="{Binding LastName}"/>
</StackLayout>
</Frame>
<ListView ItemsSource="{Binding cardDatas}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text ="{Binding CardName}"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
在 MainPage 中設置 BindingContext:
public partial class MainPage : ContentPage
{
DemoViewModel viewModel = new DemoViewModel();
public MainPage()
{
InitializeComponent();
this.BindingContext = viewModel;
}
}
演示視圖模型:
class DemoViewModel
{
public ObservableCollection<BindingUser> Data { get; set; }
public DemoViewModel() {
Data = new ObservableCollection<BindingUser>
{
new BindingUser(1, "aa"),
new BindingUser(2, "bb"),
new BindingUser(3, "cc"),
new BindingUser(4, "dd")
};
}
}
類 User 被刪除,CardData 保持不變,您也可以根據需要重新添加它。
綁定用戶:
class BindingUser
{
public int Uid { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
public ObservableCollection<CardData> cardDatas { get; set; }
public BindingUser(int uid, string name)
{
Uid = uid;
FirstName = name;
LastName = name;
cardDatas = new ObservableCollection<CardData>()
{
new CardData()
{
_id = 1,
CardName = "card 1",
},
new CardData()
{
_id = 2,
CardName = "card 2",
},
new CardData()
{
_id = 3,
CardName = "card 3",
},
};
}
}
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