C# Xamarin ListView分组问题
我在Xamarin中使用ListView进行分组时遇到问题。我看过的指南多得数不清,但我仍然无法让它正常工作。我可以看到ViewModel属性设置正确,但我得到的只是一个空白屏幕。请不要用另一个指南的链接来回答,因为我可能已经看过了,它没有帮助。我相信我很接近 类域:C# Xamarin ListView分组问题,c#,listview,xamarin.forms,grouping,C#,Listview,Xamarin.forms,Grouping,我在Xamarin中使用ListView进行分组时遇到问题。我看过的指南多得数不清,但我仍然无法让它正常工作。我可以看到ViewModel属性设置正确,但我得到的只是一个空白屏幕。请不要用另一个指南的链接来回答,因为我可能已经看过了,它没有帮助。我相信我很接近 类域: public class TechInventoryDetail { public int EquipmentInventoryDetailEntityId { get; set; } public int Te
public class TechInventoryDetail
{
public int EquipmentInventoryDetailEntityId { get; set; }
public int TechId { get; set; }
public string CodeDetail { get; set; }
public string CodeDescription { get; set; }
public int Need { get; set; }
public int Have { get; set; }
public string ServiceCategory { get; set; }
}
查看模型属性:
private ObservableRangeCollection<Models.Grouping<string, TechInventoryDetail>> _techEquipmentOverview = new ObservableRangeCollection<Models.Grouping<string, TechInventoryDetail>>();
public ObservableRangeCollection<Models.Grouping<string, TechInventoryDetail>> TechEquipmentOverview
{
get => _techEquipmentOverview;
set { _techEquipmentOverview = value; RaisePropertyChanged(); }
}
private ObserverAgeCollection\u techEquipmentOverview=new ObserverAgeCollection();
公共观察收集技术设备概述
{
get=>\u技术设备概述;
设置{u techEquipmentOverview=value;RaisePropertyChanged();}
}
使用视图模型方法设置:
public async Task GetTechEquipmentOverviewAsync()
{
var result = await _techService.GetTechEquipmentOverviewAsync(false);
if (result.Success)
{
var equipmentGrouped = result.Data.InventoryDetail.GroupBy(c => c.ServiceCategory, c => c);
var groups = equipmentGrouped.Select(g => new Models.Grouping<string, TechInventoryDetail>(g.Key, g)).ToList();
if (groups.Any())
{
TechEquipmentOverview = new ObservableRangeCollection<Models.Grouping<string, TechInventoryDetail>>();
TechEquipmentOverview.AddRange(groups);
}
}
}
公共异步任务GetTechEquipmentOverviewAsync()
{
var result=await\u techService.GetTechEquipmentOverviewAsync(false);
如果(结果、成功)
{
var equipmentGrouped=result.Data.InventoryDetail.GroupBy(c=>c.ServiceCategory,c=>c);
var groups=equipmentGrouped.Select(g=>newmodels.Grouping(g.Key,g)).ToList();
if(groups.Any())
{
TechEquipmentOverview=新的ObserverAgeCollection();
TechEquipmentOverview.AddRange(组);
}
}
}
Xaml列表视图:
<ListView HasUnevenRows="true"
IsGroupingEnabled="true"
GroupDisplayBinding="{Binding Key}"
ItemsSource="{Binding TechEquipmentOverview}">
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Padding="0,5,0,5" Orientation="Vertical">
<Label
HorizontalTextAlignment="Center"
Style="{StaticResource EquipmentGroupHeader}"
Text="{Binding Key}" />
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid Padding="5">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
<ColumnDefinition Width="*" />
<ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>
<Grid.Children>
<Label
Grid.Row="0"
Grid.ColumnSpan="4"
HorizontalTextAlignment="Center"
LineBreakMode="TailTruncation"
Style="{StaticResource DefaultSectionHeader}"
Text="{Binding CodeDetail}" />
<Label
Grid.Row="1"
Grid.Column="0"
Grid.ColumnSpan="2"
Margin="0,5,5,5"
Style="{StaticResource H1}"
Text="Need" />
<Label
Grid.Row="2"
Grid.Column="0"
Grid.ColumnSpan="2"
Margin="0,15,5,5"
LineBreakMode="TailTruncation"
Style="{StaticResource H2}"
Text="{Binding Need}" />
<Label
Grid.Row="1"
Grid.Column="2"
Grid.ColumnSpan="2"
Margin="0,5,5,5"
Style="{StaticResource H1}"
Text="Have" />
<Label
Grid.Row="2"
Grid.Column="2"
Grid.ColumnSpan="2"
Margin="0,15,5,5"
LineBreakMode="TailTruncation"
Style="{StaticResource H2}"
Text="{Binding Have}" />
</Grid.Children>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
在您的
GetTechEquipmentOverview Async
方法中,您正在重置TechEquipmentOverview
可观察集合,而UI不知道新列表
您需要在ViewModel中实现
INotifyPropertyChanged
,并通知用户界面列表引用已更改。另外,请确保您正在使用设备通知主UI线程上的UI。BeginInvokeMainThread
您的类TechInventoryDetail是否需要实现INotifyPropertyChanged?我已将ViewModel属性更改为您建议的。它似乎可以工作,但我必须刷新页面才能显示任何内容。我肯定这和你的最后一句话有关,但我不确定你的意思。有一个主UI线程,UI元素喜欢在它上面更新<代码>列表视图在更新列表时几乎要求您处于UI线程上iOS
和Android如果不在主UI线程上更新,有时甚至会出现异常。使用Device.beginInvokeMainThread
将在主线程上运行一个操作,允许UI正确更新。希望这有助于我猜他只需要在构造函数中实例化TechEquipmentOverview
列表,并且在调用GetTechEquipmentOverview Async
justClear
it.关于主UI的事情:只需将AddRange
代码更改为:Device.BeginInvokeMainThread(()=>TechEquipmentOverview.AddRange(组);