Xamarin Binding ViewCell - xamarin.forms

<ListView Grid.Column="0" ItemsSource="{Binding CardItems[0]}" RowHeight="100">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding CardItemTapCommand}" />
</StackLayout.GestureRecognizers>
<Image Source="{Binding Image}" HeightRequest="64"/>
<Label Text="{Binding Text}"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
My view has its binding context set to the corresponding viewmodel.
My CardItemTapCommand doesn't work.(i think this is happening because the binding context of each viewcell is the cardItem[0] list). Is setting the binding context of the cell to the viewmodel again a bad idea?


You can try this
<ContentPage ...
x:Name="PageName">
<ContentPage.Content>
...
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Command="{Binding Path=BindingContext.TapCommand,
Source={x:Reference PageName}}"/>
</StackLayout.GestureRecognizers>
...
</ContentPage.Content>
</ContentPage>

Related

Binding to nested Items

I have this code:
<StackLayout BindableLayout.ItemsSource="{Binding Classes}">
....
<StackLayout BindableLayout.ItemsSource="{Binding Class1}">
...
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Tapped="Class_Tapped" CommandParameter="{Binding .}" />
</StackLayout.GestureRecognizers>
</StackLayout>
</StackLayout>
The problem is that I am getting the binding of Classes and not of Class1. I want the Class1 binding in Tapped CommandParameter. Is this possible?
Thank you!

Place the inner StackLayout into the DataTemplate of the outer StackLayout , the BindingContext of the TapGestureRecognizer must be Class1 .
<StackLayout BindableLayout.ItemsSource="{Binding Classes}">
<BindableLayout.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout BindableLayout.ItemsSource="{Binding Class1}">
<StackLayout.GestureRecognizers>
<TapGestureRecognizer Tapped="Class_Tapped" CommandParameter="{Binding .}" />
</StackLayout.GestureRecognizers>
</StackLayout>
</ViewCell>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>

Grid layout in Xamarin Forms

Currently, I've got a ListView implementation that looks something like this:
{Alert1}
{Alert2}
{Alert3}
{Alert4}
{Alert5}
{Alert6]
{Alert7}
xaml:
<ListView Grid.Row="4"
ItemsSource="{Binding Alerts}"
HasUnevenRows="True"
VerticalOptions="Start"
SeparatorVisibility="None" Margin="10,0"
x:Name="AlertsList">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame BackgroundColor="#333333" Margin="0,5" Padding="5">
<StackLayout Margin="0" Padding="0">
<Label
Text="{Binding Name, Mode=OneWay}"
FontAttributes="Bold"
FontSize="Large"
HorizontalOptions="Center"
Margin="0" />
<Label
Text="{Binding Value, Mode=OneWay}"
HorizontalOptions="Center"
FontSize="Medium"
Margin="0" />
</StackLayout>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Any suggestion on how to modify this so that the output is displayed in a 2 column grid instead with equal width columns such as?
{Alert1}{Alert2}
{Alert3}{Alert4}
{Alert5}{Alert6]
{Alert7}
I'm using Xamarin Forms v2.3.3

As Jason said,you could upgrade your XF version and use CollectionView with its ItemsLayout property.
<CollectionView ItemsSource="{Binding Alerts}"
ItemsLayout="VerticalGrid, 2">
<CollectionView.ItemTemplate>
<DataTemplate>
<Frame BackgroundColor="#333333" Margin="0,5" Padding="5">
<StackLayout Margin="0" Padding="0">
<Label
Text="{Binding Name, Mode=OneWay}"
FontAttributes="Bold"
FontSize="Large"
HorizontalOptions="Center"
Margin="0" />
<Label
Text="{Binding Value, Mode=OneWay}"
HorizontalOptions="Center"
FontSize="Medium"
Margin="0" />
</StackLayout>
</Frame>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
The more you could refer to the doc.

Xamarin Formns: Multiple empty rows getting created after the data in list view

PFB the code for my list view,
<ListView HasUnevenRows="true" ItemsSource="{Binding UserEmailList}" IsGroupingEnabled="true">
<ListView.GroupHeaderTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Orientation="Vertical" Spacing="0" Margin="0" Padding="0">
<BoxView Style="{StaticResource separator}"></BoxView>
<Label Text="{Binding Heading}" Style="{StaticResource labelHeaderTitle}" />
<BoxView Style="{StaticResource separator}"></BoxView>
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.GroupHeaderTemplate>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Orientation="Horizontal" Spacing="0" >
<StackLayout IsVisible="{Binding UserEmailDetails.HasEmailAddress}" Orientation="Horizontal" HorizontalOptions="FillAndExpand">
<Label Text="{Binding UserEmailDetails.EmailAddress}" Style="{StaticResource labelListItem}" HorizontalOptions="FillAndExpand">
<Label.GestureRecognizers>
<TapGestureRecognizer Tapped="SelectEmailAddress_Tapped" CommandParameter="{Binding UserEmailDetails}" />
</Label.GestureRecognizers>
</Label>
<Image HeightRequest="16" HorizontalOptions="End" VerticalOptions="Center" Source="arrow.png" Margin="0,0,15,0">
</Image>
</StackLayout>
<StackLayout IsVisible="{Binding UserEmailDetails.HasEmailAddress, Converter={StaticResource NotConverter}}" Padding="15,0,0,0">
<Label Text="Add email" Style="{StaticResource labelLink}">
<Label.GestureRecognizers>
<TapGestureRecognizer Tapped="SelectEmailAddress_Tapped" CommandParameter="{Binding UserEmailDetails}" />
</Label.GestureRecognizers>
</Label>
</StackLayout>
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Even if there are only two rows, on IOS multiple empty rows are getting populated as in the below snapshot.
Please let me know how to avoid this and hav things working in both Android and IOS

I would hide the Separator by setting SeparatorVisibility="None" on ListView Property. If you still need the Separator I would define in the ViewCell.
<ListView HasUnevenRows="true" SeparatorVisibility="None">
The other way is to put Empty Footer on List View:
<ListView>
<ListView.Footer>
<Label />
</ListView.Footer>
</ListView>
I hope one of these helps you. Let me know if anything.

ListView not displaying labels correctly

In my Xamarin.Forms app, I have a ListView:
<ListView ItemsSource="{Binding MyItems}"
Grid.Row="1"
Margin="0,20,0,0">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Label Text="ABC" FontSize="Large" TextColor="Black" BackgroundColor="Red" Margin="20" HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand"/>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Where the "ABC" should appear, is only a thin red line for the background of the label. I don't see the actually letters. I've made many ListView before with no problem, I don't know what I'm doing wrong here?

ViewCell needs to contain a layout control, otherwise it will not render correctly.
For simplicity, you could implement a StackLayout:
<ListView
ItemsSource="{Binding MyItems}"
Grid.Row="1"
Margin="0,20,0,0>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout
HorizontalOptions="FillAndExpand"
Margin="0"
Padding="0"
Spacing="0"
VerticalOptions="Fill">
<Label
BackgroundColor="Red"
FontSize="Large"
HorizontalOptions="FillAndExpand"
HorizontalTextAlignment="Center"
Margin="20"
Text="ABC"
TextColor="Black"
VerticalOptions="FillAndExpand"
VerticalTextAlignment="Center"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>

How to implement an ItemTemplate within a ListView using XAML

How do I implement an ItemTemplate within a ListView using XAML?
If I do not use ItemTemplate, then my binding works and I receive no errors.
However, I want to format my list view.
As a result, I am attempting to use ItemTemplate but continue to hit a runtime exception:
Xamarin.Forms.Xaml.XamlParseException: Position 30:30. Cannot assign property "View": type mismatch between "Xamarin.Forms.TextCell" and "X…
I receive a runtime exception with the following XAML:
<ListView Grid.Row="1" Grid.Column="0" ItemsSource="{Binding Services}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<TextCell Text="{Binding Name}" Detail="{Binding Description}" />
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Any suggestions?

ViewCell is a class which you can use to create custom cells layouts
TextCell is a predefined cell with predefined layout.
You cannot use a Cell inside another Cell (eg. TextCell in a ViewCell).
You can create a custom cell like this:
<ListView Grid.Row="1" Grid.Column="0" ItemsSource="{Binding Services}">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Orientation="Vertical">
<Label Text="{Binding Name}" />
<Label Text="{Binding Description}" />
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
OR use a predefined one:
<ListView Grid.Row="1" Grid.Column="0" ItemsSource="{Binding Services}">
<ListView.ItemTemplate>
<DataTemplate>
<TextCell Text="{Binding Name}" Detail="{Binding Description}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
A list of predefined cells is here: http://developer.xamarin.com/guides/cross-platform/xamarin-forms/controls/cells/

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