CollectionView项未出现在发布模式中

Question

在。net Maui应用程序中，我有以下问题:我的集合视图在调试模式下工作得很好，但在发布模式下，而不是图像和两个标签，集合视图只显示一个白色矩形。onClick函数工作正常:这是xaml:

<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:vm="clr-namespace:VegaMaui"
xmlns:model="clr-namespace:VegaMaui.Model"
x:Class="VegaMaui.MenuDetails"   x:DataType="vm:MenuDetailsViewModel"        
Title="Ապրանքներ"
BackgroundColor="#f9f9f9">   
<CollectionView 
RemainingItemsThreshold="5"
RemainingItemsThresholdReachedCommand="{Binding LoadMoreS}"
SelectionMode="Single"
SelectionChanged="OnProdSelectionChanged"
ItemsSource="{Binding ProdListS}"
x:Name="prodcollect">
<CollectionView.ItemsLayout>
<GridItemsLayout Orientation="Vertical"
Span="2" />
</CollectionView.ItemsLayout>       
<CollectionView.ItemTemplate>            
<DataTemplate x:DataType="model:ProductImg">                    
<Grid Margin="5,5,5,5" Padding="1" >
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*" />                           
</Grid.ColumnDefinitions>
<Image
Grid.Row="0"                           
Grid.Column="0"                         
Source= "{Binding firstPicture}"                        
Aspect="AspectFill"/>                    
<Label Grid.Row="1"
Grid.Column="0"                      
FontAttributes="Bold"
BackgroundColor="White"
LineBreakMode="WordWrap"
Text="{Binding product_Name}"
VerticalOptions="Start" />
<Label Grid.Row="2"
Grid.Column="0"                      
FontAttributes="Bold"
LineBreakMode="WordWrap"
BackgroundColor="White"
Text="{Binding product_DisPrice, StringFormat='{0:F0} դր.'}"
TextColor ="Red" FontSize="Default"
VerticalOptions="Start" />
<Label Grid.Row="3"
Grid.Column="0"                                   
LineBreakMode="WordWrap"
BackgroundColor="White"
IsVisible="{Binding IsShowMode}"
Text="{Binding product_Price, StringFormat='{0:F0} դր.'}"
TextColor="#40414a"  FontSize="Default" 
TextDecorations="Strikethrough"
VerticalOptions="Start" />
</Grid>                    
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>   
</ContentPage>

这是ViewModel:

namespace VegaMaui
{
public  class MenuDetailsViewModel : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private int startindex = 1;
private int endindex = 10;        
private string SubGrInd = "";
private readonly VegaApi ApiControl;
private void OnPropertyChanged(string propertyName) =>
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
public MenuDetailsViewModel(string SubGroup)
{
SubGrInd = SubGroup;    
ApiControl = new();
// Task.Run(() => this.LoadData(SubGroup)).Wait();
ProdListS = new ObservableCollection<Model.Product>();
new Thread(() =>
{
LoadDataS();
}).Start();

}        
public async Task LoadDataS()
{           
var data =  await ApiControl.GetMenuDetAsync(SubGrInd, startindex,endindex);
ProdListS = new ObservableCollection<Model.Product>(data);
PropertyChanged.Invoke(this,new PropertyChangedEventArgs(nameof(ProdListS)));
}
public ICommand LoadMoreS => new Command(async () =>
{           
startindex += 16;
endindex += 16;
ObservableCollection<Model.Product> data = null;
new Thread(() =>
{
data=  ApiControl.GetMenuDetAsync(SubGrInd, startindex, endindex).Result;          
foreach (var item in data)
{
ProdListS.Add(item);
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(nameof(ProdListS)));
}               
}).Start();            
});       
public ObservableCollection<Model.Product> ProdListS { get; set; } 
}
}

}        
public async Task LoadDataS()
{           
var data =  await ApiControl.GetMenuDetAsync(SubGrInd, startindex,endindex);
ProdListS = new ObservableCollection<Model.Product>(data);
PropertyChanged.Invoke(this,new PropertyChangedEventArgs(nameof(ProdListS)));
}
public ICommand LoadMoreS => new Command(async () =>
{           
startindex += 16;
endindex += 16;
ObservableCollection<Model.Product> data = null;
new Thread(() =>
{
data=  ApiControl.GetMenuDetAsync(SubGrInd, startindex, endindex).Result;          
foreach (var item in data)
{
ProdListS.Add(item);
PropertyChanged.Invoke(this, new PropertyChangedEventArgs(nameof(ProdListS)));
}               
}).Start();            
});       
public ObservableCollection<Model.Product> ProdListS { get; set; } 
}

}

public partial class MenuDetails: ContentPage{公共字符串[]ImgList;

private MenuDetailsViewModel _mdvm;
public MenuDetails(string subGID)
{        
BindingContext = _mdvm = new MenuDetailsViewModel(subGID);
InitializeComponent();    

}
async void OnProdSelectionChanged(object sender, SelectionChangedEventArgs e)
{

Model.Product prodItem = this.prodcollect.SelectedItem as Model.Product;
int id_Param = prodItem.product_Id;
VegaApi ApiControl = new();
List<Model.ProdParams> ParamList = await ApiControl.GetParamDetAsync(id_Param.ToString());      
ProdInformation ProfilePage = new ProdInformation();
ProfilePage.Title = this.Title;
ProfilePage.BindingContext = prodItem;        
VerticalStackLayout PropsStack = ProfilePage.FindByName<VerticalStackLayout>("InfoLayout");
//Label NmLabel = ProfilePage.FindByName<Label>("prodname");
//NmLabel.Text = prodItem.product_Name;
//Label PrLabel = ProfilePage.FindByName<Label>("prodprice");
//PrLabel.Text = prodItem․+ " դր.";

// Adding Images carousel view      
string[] picarray = prodItem.product_PicturePath.Split('@');
System.Collections.ObjectModel.ObservableCollection<Promo> Data = new System.Collections.ObjectModel.ObservableCollection<Promo>();      
Data.Add(new Promo() { ImgSource =prodItem.firstPicture});
if (picarray.Count() > 1)
{          
for (int k = 1; k < picarray.Count(); k++)
{
if (picarray[k] != null && picarray[k].Length > 3)
{
Data.Add(new Promo() { ImgSource = "https://vega.am/image/"+ picarray[k] });
}
}
}

CarouselView CurCarousel= ProfilePage.FindByName<CarouselView>("pcarousel");
CurCarousel.ItemsSource = Data;
//  StackLayout slayout = new StackLayout();    


// PropsStack.Add(primage);
List<int> TitleIds = (from el in ParamList select el.Title_Id).Distinct().ToList();
if (TitleIds != null && TitleIds.Count > 0)
{
for (int j = 0; j<TitleIds.Count; j++)
{
List<Model.ProdParams> subLst= ParamList.Where(p => p.Title_Id == TitleIds[j]).ToList();
if(subLst != null && subLst.Count > 0)
{
Label ltitle= new Label();
ltitle.Text = subLst[0].Title_Name;
ltitle.FontSize = 18;
ltitle.TextColor = Color.FromRgb(16, 26, 175);
ltitle.Padding = new Thickness(3, 5, 3, 5);
ltitle.HorizontalOptions = LayoutOptions.Start;
PropsStack.Add(ltitle);
Grid CurGrid = new Grid
{

ColumnDefinitions =
{
new ColumnDefinition{Width = new GridLength(5, GridUnitType.Star)},
new ColumnDefinition{Width = new GridLength(3, GridUnitType.Star)}
}
};                    
for (int q=0;q< subLst.Count;q++)
{     
CurGrid.AddRowDefinition(new RowDefinition());


CurGrid.Add(new Label
{

Text = subLst[q].Param_Name+" ",
LineBreakMode = LineBreakMode.WordWrap,
MaxLines =2,
HorizontalOptions = LayoutOptions.Start,
VerticalOptions = LayoutOptions.Center
},0,q);
CurGrid.Add(new Label
{
Text = subLst[q].Param_Value,
LineBreakMode = LineBreakMode.WordWrap,
MaxLines = 2,
HorizontalOptions = LayoutOptions.Start,
VerticalOptions = LayoutOptions.Center
},1,q);
}
PropsStack.Add(CurGrid);
}
}
}        
await Navigation.PushAsync(ProfilePage);
}

}

Answer 1

我看到了绑定ItemsSource:

ItemsSource="{Binding ProdListS}"

指定产品模型:

<DataTemplate x:DataType="model:ProductImg">

但是在代码中你有:

public ObservableCollection<Model.Product> ProdListS { get; set; } 

这是你应该做的。

不匹配模型是完全可以的，甚至不指定一个作为DataTemplate的DataType。只要你调试。

在发行版中情况就不一样了。