Picker ItemSource values not binding in a XAML ListView

问题

Hoping you can advise as I've tried all methods to bind a picker in a Listview to my item source values using both code-behind and MVVM. The picker binding works outside of the ListView, but not inside - is this out of the box or just not possible?

Please see my list below!

code

                    <ListView
                            x:Name="TypesList"                
                            HeightRequest="53"
                            BackgroundColor="White"
                            IsGroupingEnabled="True"
                            IsPullToRefreshEnabled="false"
                            ItemsSource="{Binding Items}"                
                            IsRefreshing="{Binding IsBusy}"
                            RefreshCommand="{Binding LoadTypesCommand}"
                            SeparatorVisibility="None"  
                            >
                      
                        <ListView.ItemTemplate>
                            <DataTemplate>
                                <ViewCell Height="63">
                                    <StackLayout Orientation="Horizontal"  VerticalOptions="Center">
                                        <Grid>
                                            <Grid.RowDefinitions>
                                                <RowDefinition Height="150"/>
                                            </Grid.RowDefinitions>

                                            <Grid.ColumnDefinitions>
                                                <ColumnDefinition Width="250"/>
                                                <ColumnDefinition Width="60"/>
                                                <ColumnDefinition Width="70"/>
                                            </Grid.ColumnDefinitions>
                                            <!-- -->
                                            <Label Grid.Column="0"
                                                   Grid.Row="0"
                                                   VerticalOptions="Center"
                                                   FontAttributes="None"                                       
                                                   Text="{Binding .Name, Mode=TwoWay} "
                                                   TextColor="Black"
                                                   VerticalTextAlignment="Center"
                                                   Margin="0,15,0,110"
                                                   BackgroundColor="White" 
                                                   Padding="20,10,0,10"
                                                   FontFamily="Hiragino Sans"
                                                   FontSize="14"
                                                   HeightRequest="53"
                                                   x:Name="userLabel"                                           
                                                  />
                                           
                                            <Entry Grid.Column="1"
                                                   Grid.Row="0"
                                                   Text="{Binding .Amount, Mode=TwoWay}"
                                                   TextColor="Black"
                                                   VerticalOptions="EndAndExpand"
                                                   Margin="0,15,20,110" 
                                                   BackgroundColor="White"                                    
                                                   FontFamily="Hiragino Sans"
                                                   FontSize="14"
                                                   HeightRequest="40"
                                                   WidthRequest="55"
                                                   x:Name="userEntry"
                                            />
                                            <Picker Grid.Column="2"
                                                    Grid.Row="0"
                                                    x:Name="mPicker"
                                                    ItemsSource="{Binding UserOptions}"
                                               
                                            />
                                        </Grid>
                                    </StackLayout>
                                </ViewCell>
                            </DataTemplate> 
                        </ListView.ItemTemplate>

code

Code behind

code mPicker.ItemsSource = ViewModel.UserOptions; code

The model allocates UserOptions and this works for a picker outside the listview so I don't believe there is anything wrong with the model or this code needs to be posted.

Any help appreciated!

回答1:

List view has its own binding context. So you need to get binding context of view model and then bind to picker like this

Set a name of your view like this

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:d="http://xamarin.com/schemas/2014/forms/design"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
             x:Name="viewName">


<Picker Grid.Column="2"
        Grid.Row="0"
        x:Name="mPicker"
        ItemsSource="{Binding BindingContext.UserOptions, Source={x:Reference viewName}}"
                                               
/>

来源：https://stackoverflow.com/questions/65672124/picker-itemsource-values-not-binding-in-a-xaml-listview

标签

xaml

listview

picker