I have a ViewCell with a Picker which is in ListView:
(Simplified)
<ViewCell.View>
<Label Text="{Binding CompanyName}"/>
<Picker ItemsSource="{Binding ??this??.Employees}">
The ViewCell is bound to a Company which has a collection of Employees (Employee.Name is the field value to show)
How do I set the Picker to the Employees. Bascially I need a this.Employeess ??
The Since the list of Employees is part of the Company that is being Binded, you simple need to Bind the ItemsSource to the Employees
<ViewCell.View>
<Label Text="{Binding CompanyName}"/>
<Picker ItemsSource="{Binding Employees}">
Related
I'm new to this community / Xamarin, and I've been stuck on this for a while so I need to reach out for help now.
I have a CarouselView of ContentViews and one of the view pages need to be validated so when the field is empty, I can revert back the correct carousel page using the Current Item binding BUT - although I am correctly retrieving the current item and the content view, the UI/binding isn't updating.
ContentViews is the ObservableCollection.
<Label Text="{Binding Source={x:Reference carouselView}, Path=CurrentItem,
StringFormat='Current item: {0}', FallbackValue='Current item:'}"/>
<Label Text="{Binding Source={x:Reference carouselView}, Path=Position,
StringFormat='Position: {0}'}"/>
<CarouselView
x:Name="carouselView"
IndicatorView="indicatorView"
ItemsSource="{Binding ContentViews}"
CurrentItem="{Binding CurrentItem}"
Position="{Binding Position}"
CurrentItemChanged="OnCurrentItemChanged"
PositionChanged="OnPositionChanged">
<CarouselView.ItemTemplate>
<DataTemplate>
<ContentView Content="{Binding .}" />
</DataTemplate>
</CarouselView.ItemTemplate>
</CarouselView>
Do you have INotifyPropertyChanged implemented in you Binding Source?
check this , also check that the CarouselView Binding source is your desired class.
I have a ListView, and there are Label and Stepper in one ListView.ItemTemplate. How do I bind Stepper value changing to this Label?
<ListView x:Name="productsList"
ItemsSource="products"
HasUnevenRows="true">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout x:Name="productStack" Orientation="Vertical">
<Label x:Name="NameLabel"
Text="{Binding DisplayName}"
Font="Bold" />
<Label x:Name="count"
Text="1"/>
<Stepper x:Name="countStepper"
Minimum="1"
Increment="1" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
When I try to change Label's text in code behind
void countStepper_ValueChanged(object sender, ValueChangedEventArgs e)
{
count.Text = countStepper.Value.ToString();
}
it is said that count does not exist in the current context
How you can achieve is through below steps, if you are using MVVM
Have a model property for Label which displays the count.
In the countStepper_ValueChanged, get the object (model data) associated with that view cell and in the view model, code it to set/change the count property of label based on the value change.
I am new to xamarin and trying to display a listview. My attempt is as follows.
<ContentPage.Content>
<StackLayout>
<ListView x:Name="ComListView" RowHeight="80">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<Grid Margin="8">
<Label Grid.Column="0" Grid.Row="0" Grid.RowSpan="2" Grid.ColumnSpan="2" Text="hello world" FontAttributes="Bold" />
</Grid>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage.Content>
But when I ran the app, even I navigate to correct page; nothing display. For any other views, it will display the right output. So where could I get wrong on the listview?
You have to put items to the ListView. Currently, you only specify the ItemTemplate, which determines how an item will look (in your case, they will all look the same (i.e. Labels with 'hello world' text)). But the ListView is empty and so there are no items to show.
You can set items using the ItemsSource property of the ListView.
Usually, you use Binding inside an ItemTemplate to show item content.
Let's say we have a class Person:
class Person
{
public string Name { get; set; }
}
Then you create a List of Person objects and add it to your ListView in code:
var personnel = new List<Person>
{
new Person { Name = "Booker" },
new Person { Name = "Elizabeth" }
};
ComListView.ItemsSource = personnel;
And in your XAML, you have to set the ItemTemplate so that it shows the Name of each Person:
<Label Text="{Binding Name, Mode=OneWay}" />
Note: You can also bind to ItemsSource from XAML if you have a ViewModel.
You are not binding the data to the listview.
use the ItemSource property to bind data, either from xaml, code behind or use a binding to populate from your ViewModel
I feel like I'm missing something obvious because this is so simple. Thanks in advance for the help. I'm struggling with binding the SelectedItem of a simple ListView in a Xamarin application. I'm testing on UWP and am using Prism's MVVM BindableBase base class. Here's what I'm experiencing:
The page loads and nothing in the list is selected.
I select an item in the list.
The setter of SelectedGrade is called with a value of null.
After that, selecting items does not cause the SelectedGrade setter to be called.
Here's the relevant XAML:
<ListView BackgroundColor="#7F7F7F"
CachingStrategy="RecycleElement"
IsPullToRefreshEnabled="True"
IsRefreshing="{Binding IsBusy, Mode=OneWay}"
ItemsSource="{Binding Grades, Mode=OneWay}"
SelectedItem="{Binding SelectedGrade, Mode=TwoWay}"
RefreshCommand="{Binding RefreshCommand}"
RowHeight="50">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout HorizontalOptions="FillAndExpand"
VerticalOptions="CenterAndExpand"
Orientation="Horizontal"
Padding="10">
<Label HorizontalOptions="FillAndExpand"
Text="{Binding Title}"
TextColor="#272832"/>
<Label HorizontalOptions="FillAndExpand"
Text="{Binding Score}"
TextColor="Aquamarine" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Here's the ViewModel:
Grade _selectedGrade;
public Grade SelectedGrade
{
get { return _selectedGrade; }
set { SetProperty(ref _selectedGrade, value); } // this gets set to NULL the first time i select an item then never gets set again
}
Edit: I've also added an ItemSelected event listener in the code-behind and it is not being fired after the initial item is selected. The one time it is fired, the SelectedItemChangedEventArgs reveal that the ListView's SelectedItem is null. I can also see at this time that the ListView's ItemsSource has a collection of three items in it, as I would expect. I'm quite confused as to why the ListView thinks the SelectedItem is null and why it is not broadcasting when the selected item changes.
It looks like this was a bug in Xamarin. I upgraded from Xamarin.Forms 3.0.0.550146 to 3.1.0.637273 and now it works.
I have faced with the similar issue when List does not bind to view model with SelectedItem and Xamarin forms 5.0.0.2244.
It was resolved with setting default value of List property to new List() object instead null value in the view model before setting binding context . After that binding has became working.
I am trying to create a listview where users can select the list item to view the store and also be able to click on the image to take them to the product detail.
How can I add a command in the ViewCell?
<ListView ItemsSource="{Binding myData}" x:Name="myListView" SelectedItem="{Binding SelectedStore}" >
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Grid>
<Label Text="{Binding Title}" />
<Image Source="product.png" >
<Image.GestureRecognizers>
<TapGestureRecognizer Command="{Binding ItemTapCommand}" CommandParameter="Id" />
</Image.GestureRecognizers>
</Image>
</Grid>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
public ICommand ItemTapCommand => new Command(ShowSelectedProductAsync());
private async Task ShowSelectedProductAsync()
{
//take them to view the item detail
}
The problem is that you are attempting to bind to a command that is not located on the individual item within the ListView; the BindingContext on your Image is the individual items inside your myData collection.
With other frameworks, for example, Wpf, you would simply use the RelativeSource part of binding to tell the control to look for your command on the BindingContext of another control, however this isn't possible in Xamarin Forms (RelativeSource is not supported).
What you can do is the following, but it requires your UserControl to have an x:Name:
<TapGestureRecognizer Command="{Bindind Path=BindingContext.ItemTapCommand,
Source={x:Reference MyUserControl}}"
CommandParameter="{Binding Id}" />
What this says is to use the UserControl as the source for the binding, and the property is a nested property on that UserControl composed of BindingContext.ItemTapCommand.
As a bonus, I updated the code because I felt that you probably meant to bind the value of the Id property of each record as the command parameter, and not merely to send the string "Id" as the command parameter.