如何从另一个 ViewModel 中访问 ObservableCollection？

huangapple
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英文:

How to access ObservableCollection from another ViewModel?

问题

I have a BaseViewModel where I define my ObservableCollection and then I populate it. In another ViewModel I have a Grid and I bind it to my collection, everything works.

  1. public partial class BaseViewModel : ObservableObject
  2. {
  3.     [ObservableProperty]
  4.     private ObservableCollection<Patient> patientInfo;
  6.     public BaseViewModel()
  7.     {
  8.         PopulateObservableCollection();
  9.     }
  11.     public void PopulateObservableCollection()
  12.     {
  13.         PatientInfo = new ObservableCollection<Patient>();
  14.         try
  15.         {
  16.             string query = "select * from " + App.userDetails.DbTable;
  17.             SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(query, conn);
  18.             using (sqlDataAdapter)
  19.             {
  20.                 System.Data.DataTable dt = new System.Data.DataTable();
  21.                 sqlDataAdapter.Fill(dt);
  22.                 foreach (System.Data.DataRow row in dt.Rows)
  23.                     PatientInfo.Add(new Patient(Convert.ToInt32(row[0]), row[1].ToString(), row[2].ToString(), row[3].ToString(), row[4].ToString(), row[5].ToString(), row[6].ToString(), row[7].ToString(), row[8].ToString()));
  24.             }
  25.         }
  26.         catch (Exception)
  27.         { }
  28.     }
  29. }

Now I want to change my ObservableCollection from the other ViewModels and be able to access the memory from the BaseViewModel.

Next a ViewModel where I try to change the ObservableCollection, but I'm not accessing the objected created in the BaseViewModel:

  1. [QueryProperty(nameof(Patient), nameof(Patient))]
  2. public partial class EditingViewModel : BaseViewModel
  3. {
  4.     [ObservableProperty] private Patient patient;
  5.     
  6.     [RelayCommand]
  7.     private async Task Delete()
  8.     {
  9.         try
  10.         {
  11.             string query = "DELETE from " + App.userDetails.DbTable + " WHERE id = @patientId";
  12.             sqlConnection = new SqlConnection(conn);
  13.             SqlCommand sqlCommand = new SqlCommand(query, sqlConnection);
  14.             SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlCommand);
  16.             using (sqlDataAdapter)
  17.             {
  18.                 sqlConnection.Open();
  19.                 sqlCommand.Parameters.AddWithValue("@patientId", Patient.Id);
  20.                 sqlCommand.ExecuteScalar();
  21.             }
  23.             //Removing object from observable collection
  24.             PatientInfo.Remove(PatientInfo.SingleOrDefault(x => x.Id == Patient.Id));
  25.         }
  26.         catch (Exception ex)
  27.         {
  28.             await Shell.Current.DisplayAlert("Aplicação", ex.ToString(), "Sair");
  29.         }
  30.         finally
  31.         {
  32.             sqlConnection.Close();
  33.         }
  34.     }
  35. }

My "DashboardView" where the grid is defined:

  1. <?xml version="1.0" encoding="utf-8" ?>
  2. <ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
  3.              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
  4.              xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
  5.              x:Class="PatientAppMultiPlatf.Views.DashboardPage"
  6.              xmlns:viewModels="clr-namespace:PatientAppMultiPlatf.ViewModels"
  7.              xmlns:syncfusion="clr-namespace:Syncfusion.Maui.DataGrid;assembly=Syncfusion.Maui.DataGrid"
  8.              Title="Lista de Pacientes">
  10.     <VerticalStackLayout Padding="10">
  11.         <HorizontalStackLayout Padding="20" >
  12.             <Button 
  13.                    Text="Exportar" Command="{Binding PDFCommand}" CornerRadius="20" WidthRequest="100" HorizontalOptions="End">
  14.             </Button>
  15.             <Button
  16.                 Text="Filtrar" Command="{Binding FilterCommand}" WidthRequest="100" CornerRadius="20" HorizontalOptions="Center">
  17.             </Button>
  18.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  19.                 <Entry Text="{Binding Date}" VerticalOptions="Center" Placeholder="Data"/>
  20.             </Frame>
  21.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  22.                 <Entry Text="{Binding Name}" VerticalOptions="Center" Placeholder="Nome"/>
  23.             </Frame>
  24.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  25.                 <Entry Text="{Binding Age}" VerticalOptions="Center" Placeholder="Idade"/>
  26.             </Frame>
  27.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  28.                 <Entry Text="{Binding Gender}" VerticalOptions="Center" Placeholder="Genero"/>
  29.             </Frame>
  30.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  31.                 <Entry Text="{Binding Process}" VerticalOptions="Center" Placeholder="Processo"/>
  32.             </Frame>
  33.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  34.                 <Entry Text="{Binding Diagnostic}" VerticalOptions="Center" Placeholder="Diagnostico"/>
  35.             </Frame>
  36.             <Frame HeightRequest="45" Padding="5" HasShadow="True" BorderColor="White">
  37.                 <Entry Text="{Binding Discharge}" VerticalOptions="Center" Placeholder="Alta"/>
  38.             </Frame>
  40.         </HorizontalStackLayout>
  41.         <syncfusion:SfDataGrid x:Name="dataGrid" DefaultColumnWidth="90"
  42.             ItemsSource="{Binding PatientInfo}" SortingMode="Single" SelectedRow="{Binding SelectedPatient}" SelectionMode="Single"
  43.                                HeightRequest="600"  VerticalOptions="CenterAndExpand" HorizontalOptions="Center" AutoGenerateColumnsMode="None">
  44.             <syncfusion:SfDataGrid.Behaviors>
  45.                 <toolkit:EventToCommandBehavior
  46.                     EventName="CellDoubleTapped"
  47.                     Command="{Binding CellDoubleTappedCommand}">
  48.                 </toolkit:EventToCommandBehavior>
  49.             </syncfusion:SfDataGrid.Behaviors>
  50.             <syncfusion:SfDataGrid.Columns VerticalOptions="CenterAndExpand" HorizontalOptions="CenterAndExpand">
  51.                 <syncfusion:DataGridTextColumn  HeaderText="Data" MappingName="Date"/>
  52.                 <syncfusion:DataGridTextColumn  HeaderText="Nome" MappingName="Name" ColumnWidthMode="Fill"/>
  53.                 <syncfusion:DataGridTextColumn  HeaderText="Idade" MappingName="Age"/>
  54.                 <syncfusion:DataGridTextColumn  HeaderText="Genero" MappingName="Gender"/>
  55.                 <syncfusion:DataGridTextColumn  HeaderText="Processo" MappingName="Process"/>
  56.                 <syncfusion:DataGridTextColumn  HeaderText="Diagnostico" MappingName="Diagnostic" ColumnWidthMode="Fill"/>
  57.                 <syncfusion:DataGridTextColumn  HeaderText="Alta" MappingName="Discharge" ColumnWidthMode="LastColumnFill"/>
  58.             </syncfusion:SfDataGrid.Columns>
  59.                         <syncfusion:SfDataGrid.DefaultStyle>
  60.                 <syncfusion:DataGridStyle HeaderRowBackground="#b2cbc8" HeaderRowTextColor="Black" />
  61.             </syncfusion:SfDataGrid.DefaultStyle>
  62.         </syncfusion:SfDataGrid>
  63.     </VerticalStackLayout>
  64. </ContentPage>

Each view has a xaml.cs where I bind the page to the view model:

  1. namespace PatientAppMultiPlatf.Views;
  3. public partial class DashboardPage : ContentPage
  4. {
  5.     public DashboardPage(DashboardViewModel viewModel)
  6.     {
  7.         InitializeComponent();
  8.         BindingContext = viewModel;
  9.     }
  10. }

I'm using MVVM architecture. What is the best method to access the ObservableCollection that is being

英文:

I have a BaseViewModel where I define my ObservableCollection and then I populate it. In another ViewModel I have a Grid and I bind it to my collection, everything works.

  1. public partial class BaseViewModel : ObservableObject
  2. {
  3.     [ObservableProperty]
  4.     private ObservableCollection&lt;Patient&gt; patientInfo;
  6.     public BaseViewModel()
  7.     {
  8.         PopulateObservableCollection();
  9.     }
  11.     public void PopulateObservableCollection()
  12.     {
  13.         PatientInfo = new ObservableCollection&lt;Patient&gt;();
  14.         try
  15.         {
  16.             string query = &quot;select * from &quot; + App.userDetails.DbTable;
  17.             SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(query, conn);
  18.             using (sqlDataAdapter)
  19.             {
  20.                 System.Data.DataTable dt = new System.Data.DataTable();
  21.                 sqlDataAdapter.Fill(dt);
  22.                 foreach (System.Data.DataRow row in dt.Rows)
  23.                     PatientInfo.Add(new Patient(Convert.ToInt32(row[0]), row[1].ToString(), row[2].ToString(), row[3].ToString(), row[4].ToString(), row[5].ToString(), row[6].ToString(), row[7].ToString(), row[8].ToString()));
  24.             }
  25.         }
  26.         catch (Exception)
  27.         { }
  28.     }
  29. }

Now I want to change my ObservableCollection from the other ViewModels and be able to access the memory from the BaseViewModel.

Next a ViewModel where I try to change the ObservableCollection, but I'm not accessing the objected created in the BaseViewModel:

  1. [QueryProperty(nameof(Patient), nameof(Patient))]
  2. public partial class EditingViewModel : BaseViewModel
  3. {
  4.     [ObservableProperty] private Patient patient;
  5.     
  6.     [RelayCommand]
  7.     private async Task Delete()
  8.     {
  9.         try
  10.         {
  11.             string query = &quot;DELETE from &quot; + App.userDetails.DbTable + &quot; WHERE id = @patientId&quot;;
  12.             sqlConnection = new SqlConnection(conn);
  13.             SqlCommand sqlCommand = new SqlCommand(query, sqlConnection);
  14.             SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(sqlCommand);
  16.             using (sqlDataAdapter)
  17.             {
  18.                 sqlConnection.Open();
  19.                 sqlCommand.Parameters.AddWithValue(&quot;@patientId&quot;, Patient.Id);
  20.                 sqlCommand.ExecuteScalar();
  21.             }
  23.             //Removing object from observable collection
  24.             PatientInfo.Remove(PatientInfo.SingleOrDefault(x =&gt; x.Id == Patient.Id));
  25.         }
  26.         catch (Exception ex)
  27.         {
  28.             await Shell.Current.DisplayAlert(&quot;Aplica&#231;ao&quot;, ex.ToString(), &quot;Sair&quot;);
  29.         }
  30.         finally
  31.         {
  32.             sqlConnection.Close();
  33.         }
  34.     }
  35. }

My "DashboardView" where the grid is defined:

  1. &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot; ?&gt;
  2. &lt;ContentPage xmlns=&quot;http://schemas.microsoft.com/dotnet/2021/maui&quot;
  3.              xmlns:x=&quot;http://schemas.microsoft.com/winfx/2009/xaml&quot;
  4.              xmlns:toolkit=&quot;http://schemas.microsoft.com/dotnet/2022/maui/toolkit&quot;
  5.              x:Class=&quot;PatientAppMultiPlatf.Views.DashboardPage&quot;
  6.              xmlns:viewModels=&quot;clr-namespace:PatientAppMultiPlatf.ViewModels&quot;
  7.              xmlns:syncfusion=&quot;clr-namespace:Syncfusion.Maui.DataGrid;assembly=Syncfusion.Maui.DataGrid&quot;
  8.              Title=&quot;Lista de Pacientes&quot;&gt;
  10.     &lt;VerticalStackLayout Padding=&quot;10&quot;&gt;
  11.         &lt;HorizontalStackLayout Padding=&quot;20&quot; &gt;
  12.             &lt;Button 
  13.                    Text=&quot;Exportar&quot; Command=&quot;{Binding PDFCommand}&quot; CornerRadius=&quot;20&quot; WidthRequest=&quot;100&quot; HorizontalOptions=&quot;End&quot;&gt;
  14.             &lt;/Button&gt;
  15.             &lt;Button
  16.                 Text=&quot;Filtrar&quot; Command=&quot;{Binding FilterCommand}&quot; WidthRequest=&quot;100&quot; CornerRadius=&quot;20&quot; HorizontalOptions=&quot;Center&quot;&gt;
  17.             &lt;/Button&gt;
  18.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  19.                 &lt;Entry Text=&quot;{Binding Date}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Data&quot;/&gt;
  20.             &lt;/Frame&gt;
  21.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  22.                 &lt;Entry Text=&quot;{Binding Name}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Nome&quot;/&gt;
  23.             &lt;/Frame&gt;
  24.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  25.                 &lt;Entry Text=&quot;{Binding Age}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Idade&quot;/&gt;
  26.             &lt;/Frame&gt;
  27.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  28.                 &lt;Entry Text=&quot;{Binding Gender}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Genero&quot;/&gt;
  29.             &lt;/Frame&gt;
  30.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  31.                 &lt;Entry Text=&quot;{Binding Process}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Processo&quot;/&gt;
  32.             &lt;/Frame&gt;
  33.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  34.                 &lt;Entry Text=&quot;{Binding Diagnostic}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Diagnostico&quot;/&gt;
  35.             &lt;/Frame&gt;
  36.             &lt;Frame HeightRequest=&quot;45&quot; Padding=&quot;5&quot; HasShadow=&quot;True&quot; BorderColor=&quot;White&quot;&gt;
  37.                 &lt;Entry Text=&quot;{Binding Discharge}&quot; VerticalOptions=&quot;Center&quot; Placeholder=&quot;Alta&quot;/&gt;
  38.             &lt;/Frame&gt;
  40.         &lt;/HorizontalStackLayout&gt;
  41.         &lt;syncfusion:SfDataGrid x:Name=&quot;dataGrid&quot; DefaultColumnWidth=&quot;90&quot;
  42.             ItemsSource=&quot;{Binding PatientInfo}&quot; SortingMode=&quot;Single&quot; SelectedRow=&quot;{Binding SelectedPatient}&quot; SelectionMode=&quot;Single&quot;
  43.                                HeightRequest=&quot;600&quot;  VerticalOptions=&quot;CenterAndExpand&quot; HorizontalOptions=&quot;Center&quot; AutoGenerateColumnsMode=&quot;None&quot;&gt;
  44.             &lt;syncfusion:SfDataGrid.Behaviors&gt;
  45.                 &lt;toolkit:EventToCommandBehavior
  46.                     EventName=&quot;CellDoubleTapped&quot;
  47.                     Command=&quot;{Binding CellDoubleTappedCommand}&quot;&gt;
  48.                 &lt;/toolkit:EventToCommandBehavior&gt;
  49.             &lt;/syncfusion:SfDataGrid.Behaviors&gt;
  50.             &lt;syncfusion:SfDataGrid.Columns VerticalOptions=&quot;CenterAndExpand&quot; HorizontalOptions=&quot;CenterAndExpand&quot;&gt;
  51.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Data&quot; MappingName=&quot;Date&quot;/&gt;
  52.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Nome&quot; MappingName=&quot;Name&quot; ColumnWidthMode=&quot;Fill&quot;/&gt;
  53.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Idade&quot; MappingName=&quot;Age&quot;/&gt;
  54.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Genero&quot; MappingName=&quot;Gender&quot;/&gt;
  55.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Processo&quot; MappingName=&quot;Process&quot;/&gt;
  56.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Diagnostico&quot; MappingName=&quot;Diagnostic&quot; ColumnWidthMode=&quot;Fill&quot;/&gt;
  57.                 &lt;syncfusion:DataGridTextColumn  HeaderText=&quot;Alta&quot; MappingName=&quot;Discharge&quot; ColumnWidthMode=&quot;LastColumnFill&quot;/&gt;
  58.             &lt;/syncfusion:SfDataGrid.Columns&gt;
  59.                         &lt;syncfusion:SfDataGrid.DefaultStyle&gt;
  60.                 &lt;syncfusion:DataGridStyle HeaderRowBackground=&quot;#b2cbc8&quot; HeaderRowTextColor=&quot;Black&quot; /&gt;
  61.             &lt;/syncfusion:SfDataGrid.DefaultStyle&gt;
  62.         &lt;/syncfusion:SfDataGrid&gt;
  63.     &lt;/VerticalStackLayout&gt;
  64. &lt;/ContentPage&gt;

Each view has a xaml.cs where I bind the page to the view model:

  1. namespace PatientAppMultiPlatf.Views;
  3. public partial class DashboardPage : ContentPage
  4. {
  5. 	public DashboardPage(DashboardViewModel viewModel)
  6. 	{
  7. 		InitializeComponent();
  8. 		BindingContext = viewModel;
  9. 	}
  10. }

I'm using MVVM architecture. What is the best method to access the ObservableCollection that is being binded?

答案1

得分: 3

在BaseViewModel中，将以下部分进行更改：

  1. private ObservableCollection&lt;Patient&gt; patientInfo;

更改为：

  1. protected ObservableCollection&lt;Patient&gt; patientInfo;
英文:

In the BaseViewModel, change

  1. [ObservableProperty]
  2. private ObservableCollection&lt;Patient&gt; patientInfo;

to

  1. [ObservableProperty]
  2. protected ObservableCollection&lt;Patient&gt; patientInfo;

答案2

得分: 1

ObservableCollections 不是 ObservableProperties。

对于集合本身的更改足以通知任何更改。

如果我担心将其设置为其他内容，通常会这样做：

  1. public ObservableCollection MyProperty {get;} = new();

此外，我没有看到您的 x:DataType 在任何地方。为什么没有设置它，以及为什么您的 VisualElement 有名称？

编辑：我不确定我是否足够强调“PUBLIC”这个词，所以我想再次指出。

英文:

ObservableCollections are not ObservableProperties.

The change to the collection itself is more than enough to notify any changes.

If I am concerned about setting it to something else, I usually do this:

  1. **public** ObservableCollection MyProperty {get;} = new();

Also, I do not see anywhere your x:DataType. Why are you not setting it, and why is your VisualElement named?

Edit: I am not sure I put enough stress on the word PUBLIC, so I want to point it out again here.

答案3

得分: 0

根据您的代码，我创建了一个演示，它可以从继承自父类（BaseViewModel）属性的PatientInfo中移除项目。您可以参考以下代码：

BaseViewModel.cs

  1. public partial class BaseViewModel : ObservableObject
  2. {
  3.     [ObservableProperty]
  4.     private ObservableCollection<Patient> patientInfo;
  6.     public BaseViewModel()
  7.     {
  8.         PopulateObservableCollection();
  9.     }
  11.     public void PopulateObservableCollection()
  12.     {
  13.         PatientInfo = new ObservableCollection<Patient>();
  14.         try
  15.         {
  16.             PatientInfo.Add(new Patient { Id = 01, Name = "test1" });
  17.             PatientInfo.Add(new Patient { Id = 02, Name = "test2" });
  18.             PatientInfo.Add(new Patient { Id = 03, Name = "test3" });
  19.         }
  20.         catch (Exception)
  21.         { }
  22.     }
  23. }
  25. public class Patient
  26. {
  27.     public int Id { get; set; }
  28.     public string Name { get; set; }
  29. }

EditingViewModel.cs

  1. public partial class EditingViewModel : BaseViewModel
  2. {
  3.     [RelayCommand]
  4.     private async Task Delete()
  5.     {
  6.         try
  7.         {
  8.             // 从可观察集合中移除对象
  9.             // 这里我可以从父类`BaseViewModel`的`PatientInfo`中移除项目
  10.             PatientInfo.RemoveAt(0);
  11.         }
  12.         catch (Exception ex)
  13.         {
  14.             await Shell.Current.DisplayAlert("应用", ex.ToString(), "退出");
  15.         }
  16.         finally
  17.         {
  18.         }
  19.     }
  20. }

MainPage.xaml

  1. <?xml version="1.0" encoding="utf-8" ?>
  2. <ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
  3.              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
  4.              xmlns:MauiMvvmApp="clr-namespace:MauiMvvmApp226"
  5.              x:Class="MauiMvvmApp226.MainPage">
  7.     <ContentPage.BindingContext>
  8.         <MauiMvvmApp:EditingViewModel></MauiMvvmApp:EditingViewModel>
  9.     </ContentPage.BindingContext>
  11.     <VerticalStackLayout
  12.         Spacing="25"
  13.         Padding="30,0"
  14.         VerticalOptions="Start">
  16.         <ListView ItemsSource="{Binding PatientInfo}">
  17.             <ListView.ItemTemplate>
  18.                 <DataTemplate>
  19.                     <TextCell Text="{Binding Id}"
  20.                               Detail="{Binding Name}"
  21.                               TextColor="#f35e20"
  22.                               DetailColor="#503026" />
  23.                 </DataTemplate>
  24.             </ListView.ItemTemplate>
  25.         </ListView>
  27.         <Button
  28.             Command="{Binding DeleteCommand}"
  29.             x:Name="CounterBtn"
  30.             Text="点击我"
  31.             HorizontalOptions="Center" />
  33.     </VerticalStackLayout>
  34. </ContentPage>
英文:

Based on your code,I created a demo and it could remove the item from PatientInfo which inherits from the properties of the parent class( BaseViewModel)

You can refer to the following code:

BaseViewModel.cs

  1. public partial class BaseViewModel: ObservableObject 
  2. {
  3. [ObservableProperty]
  4. private ObservableCollection&lt;Patient&gt; patientInfo;
  5. public BaseViewModel()
  6. {
  7. PopulateObservableCollection();
  8. }
  9. public void PopulateObservableCollection()
  10. {
  11. PatientInfo = new ObservableCollection&lt;Patient&gt;();
  12. try
  13. {
  14. PatientInfo.Add(new Patient { Id = 01, Name=&quot;test1&quot;});
  15. PatientInfo.Add(new Patient { Id = 02, Name = &quot;test2&quot; });
  16. PatientInfo.Add(new Patient { Id = 03, Name = &quot;test3&quot; });
  17. }
  18. catch (Exception)
  19. { }
  20. }
  21. }
  22. public class Patient 
  23. {
  24. public int Id { get; set; }
  25. public string Name { get; set; }
  26. }

EditingViewModel.cs

   

  1.   public partial class EditingViewModel : BaseViewModel 
  2. {
  3. //[ObservableProperty] private Patient patient;
  4. [RelayCommand]
  5. private async Task Delete()
  6. {
  7. try
  8. {
  9. //Removing object from observable collection
  10. //here I could remove the item from PatientInfo from parent class `BaseViewModel `
  11. PatientInfo.RemoveAt(0);
  12. }
  13. catch (Exception ex)
  14. {
  15. await Shell.Current.DisplayAlert(&quot;Aplica&#231;ao&quot;, ex.ToString(), &quot;Sair&quot;);
  16. }
  17. finally
  18. {
  19. }
  20. }
  21. }

MainPage.xaml

  1. &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot; ?&gt; 
  2. &lt;ContentPage xmlns=&quot;http://schemas.microsoft.com/dotnet/2021/maui&quot;
  3. xmlns:x=&quot;http://schemas.microsoft.com/winfx/2009/xaml&quot;
  4. xmlns:MauiMvvmApp=&quot;clr-namespace:MauiMvvmApp226&quot;
  5. x:Class=&quot;MauiMvvmApp226.MainPage&quot;&gt;
  6. &lt;ContentPage.BindingContext&gt;
  7. &lt;MauiMvvmApp:EditingViewModel&gt;&lt;/MauiMvvmApp:EditingViewModel&gt;
  8. &lt;/ContentPage.BindingContext&gt;
  9. &lt;VerticalStackLayout
  10. Spacing=&quot;25&quot;
  11. Padding=&quot;30,0&quot;
  12. VerticalOptions=&quot;Start&quot;&gt;
  13. &lt;ListView ItemsSource=&quot;{Binding PatientInfo}&quot;&gt;
  14. &lt;ListView.ItemTemplate&gt;
  15. &lt;DataTemplate&gt;
  16. &lt;TextCell Text=&quot;{Binding Id}&quot;
  17. Detail=&quot;{Binding Name}&quot;
  18. TextColor=&quot;#f35e20&quot;
  19. DetailColor=&quot;#503026&quot; /&gt;
  20. &lt;/DataTemplate&gt;
  21. &lt;/ListView.ItemTemplate&gt;
  22. &lt;/ListView&gt;
  23. &lt;Button
  24. Command=&quot;{ Binding DeleteCommand}&quot;
  25. x:Name=&quot;CounterBtn&quot;
  26. Text=&quot;Click me&quot;
  27. HorizontalOptions=&quot;Center&quot; /&gt;
  28. &lt;/VerticalStackLayout&gt;
  29. &lt;/ContentPage&gt;  

 

huangapple
  • 本文由 发表于 2023年2月24日 17:36:28
  • 转载请务必保留本文链接：https://go.coder-hub.com/75554868.html
  • .net
  • c#
  • maui
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