In my page.xaml has the declaration as follows
<Label Text="Location" Style="{StaticResource labelStyle}" />
<ContentView Style="{StaticResource fieldView}">
<Label Text="{Binding Title}" Style="{StaticResource fieldStyle}" />
</ContentView>
I am trying to access the variable Location.Text in xaml.cs page. However, I couldn't access the syntax.
You need to assign a name to an element to access it from the code behind:
in the XAML:
<Label x:Name="txtLoc" Text="Location" Style="{StaticResource labelStyle}" />
in the code behind:
var loc = txtLoc.Text;
Related
I am learning to understand, how the binding mechanism works in XAML for .NET MAUI. I am assuming this is the same for all XAML projects, WPF, MAUI etc.
At the end is the whole XAML.
This XAML works fine:
<Button WidthRequest="150" Text="Add Activity"
Command="{Binding AddActivityEntityCommand}"
IsEnabled="{Binding IsNotBusy}"
Grid.Row="2"
Margin="8"/>
Is the reason why this works because the Button is part of the ContentPage, which has it's x:DataType set to MainPageViewModel, which is where the command lives?
The Binding is set to AddActivityEntityCommand, while the actual method signature is
async Task AddActivityEntityAsync(). How is this resolved? Since it obviously doesn't match the name, but it works. And what are the method signature requirements for this to work/being recognized?
This on the other hand, doesn't just work as easy out of the box:
<Label HorizontalOptions="End" TextColor="Red" Padding="0,0,10,0" Text="🗑"
IsVisible="{Binding IsSynchronized}">
<Label.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding Source={x:Type viewmodel:MainPageViewModel},
Path=DeleteActivityCommand}" />
</Label.GestureRecognizers>
</Label>
In this context, adding Command="{Binding DeleteActivityCommand} doesn't work, because it derives its Path from <DataTemplate x:DataType="model:ActivityEntity">, I am assuming, which is the data object and not the ViewModel, where the command actually is.
The problem here is, that as soon as I enter this XAML Command="{Binding Source={x:Type viewmodel:MainPageViewModel}, Path=DeleteActivityCommand}", the CollectionView shows empty and there is an unhandled exception thrown when the view is loaded:
System.Reflection.TargetException: Object does not match target type.
The method signature for this command is this async Task DeleteActivityAsync()
What am I missing?
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage
x:Class="OnesieMobile.View.MainPage"
xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:model="clr-namespace:OnesieMobile.Model"
xmlns:viewmodel="clr-namespace:OnesieMobile.ViewModel"
x:DataType="viewmodel:MainPageViewModel"
Title="{Binding Title}">
<Grid
ColumnDefinitions="*"
RowDefinitions="20,50,50,*"
RowSpacing="0">
<Label HorizontalOptions="End" Margin="10,0,10,0" Text="{Binding CurrentDateTime}" Grid.Row="0"/>
<Entry Margin="10,0,10,0"
Grid.Row="1" x:Name="entryNewActivity"
Placeholder="New Activityssss" HeightRequest="30" Text="{Binding NewActivityTitle}" />
<Button WidthRequest="150" Text="Add Activity"
Command="{Binding AddActivityEntityCommand}"
IsEnabled="{Binding IsNotBusy}"
Grid.Row="2"
Margin="8"/>
<CollectionView
Grid.Row="3"
ItemsSource="{Binding ActivityEntities}"
SelectionMode="None">
<CollectionView.ItemTemplate>
<DataTemplate x:DataType="model:ActivityEntity">
<Grid Padding="10,0,10,0">
<Frame Style="{StaticResource CardView}">
<Grid ColumnDefinitions="*,30,50">
<StackLayout Padding="10,5,0,0" Grid.Column="0">
<Label Text="{Binding Title}" />
</StackLayout>
<StackLayout Padding="10,5,0,0" Grid.Column="1">
<Label HorizontalOptions="End" TextColor="Red"
Padding="0,0,10,0" Text="🗑" IsVisible="{Binding IsSynchronized}" >
<Label.GestureRecognizers>
<TapGestureRecognizer
Command="{Binding Source={x:Type viewmodel:MainPageViewModel},
Path=DeleteActivityCommand}" />
</Label.GestureRecognizers>
</Label>
</StackLayout>
<StackLayout Padding="10,5,0,0" Grid.Column="2">
<Label HorizontalOptions="End"
Padding="0,0,10,0" Text="✔" IsVisible="{Binding IsSynchronized}" />
</StackLayout>
</Grid>
</Frame>
</Grid>
</DataTemplate>
</CollectionView.ItemTemplate>
</CollectionView>
<ActivityIndicator IsVisible="{Binding IsBusy}"
IsRunning="{Binding IsBusy}"
HorizontalOptions="FillAndExpand"
VerticalOptions="CenterAndExpand"
Grid.RowSpan="3"
Grid.ColumnSpan="2"/>
</Grid>
</ContentPage>
Update:
MainPageViewModel.cs contains these Commands
[ICommand]
async Task DeleteActivityAsync()
{
}
[ICommand]
async Task AddActivityEntityAsync()
{
}
Inside an item template, there are several ways to refer to the original BindingContext. I like to do it by getting it from the collection itself:
<CollectionView x:Name="myCollection" ...>
...
<CollectionView.ItemTemplate>
...
Command="{Binding Source={x:Reference myCollection},
Path=BindingContext.DeleteActivityCommand}" />
FUTURE TBD:
I don't like the command name not existing anywhere in the implementing code. Hopefully there will eventually be a way to specify the command name in the ICommand attribute, to make it obvious:
// This won't work today.
[ICommand Name="DeleteActivityCommand"]
...
For now, we have to learn [ICommand]'s magic naming rules, which seem to be "Remove Async from end (if present); Add Command to end".
I'm using the xamarin extended toolkit to show some Expanders in my application. What I'm trying to do is access an element in my Expander.ContentTemplate by setting x:Name. However when I try to access the element in my code-behind it doesn't find anything. What is the correct way to access any Label/Entry/Picker by name so I can manipulate it in the code-behind?
<xct:Expander Margin="0,0,0,20">
<xct:Expander.Header>
<Grid>
<Label FontAttributes="Bold" Text="Bookings" FontSize="Medium"/>
<Image Source="expand.png" HorizontalOptions="End"
VerticalOptions="Start">
<Image.Triggers>
<DataTrigger TargetType="Image"
Binding="{Binding Source={RelativeSource AncestorType={x:Type xct:Expander}}, Path=IsExpanded}"
Value="True">
<Setter Property="Source"
Value="collapse.png" />
</DataTrigger>
</Image.Triggers>
</Image>
</Grid>
</xct:Expander.Header>
<xct:Expander.ContentTemplate>
<DataTemplate>
<StackLayout Margin="0,10">
<Label x:Name="LabelDefaultPickup" FontAttributes="Bold" Text="Default Pickup location"/>
<Picker x:Name="PickupPicker" ItemsSource="{Binding ActivePickupList, Source={ x:Reference profilePage}}" ItemDisplayBinding="{Binding naam}" SelectedIndexChanged="PickupPicker_SelectedIndexChanged"/>
<Label x:Name="LabelDefaultPickupTime" FontAttributes="Bold" Text="Default Pickup time"/>
<Entry x:Name="DefaultPickupTime" Placeholder="pickup time" Text="{Binding Path=uurHeen}"/>
<Label x:Name="LabelDefaultDeparture" FontAttributes="Bold" Text="Default work location"/>
<Entry x:Name="DefaultDeparture" Placeholder="Location id" Text="{Binding Path=corp_id}"/>
<Label x:Name="LabelDefaultDepartureTime" FontAttributes="Bold" Text="Default Departure time"/>
<Entry x:Name="DefaultDepartureTime" Placeholder="Location id" Text="{Binding Path=uurTerug}"/>
</StackLayout>
</DataTemplate>
</xct:Expander.ContentTemplate>
</xct:Expander>
After reading the docs again, I removed the ContentTemplate tags (content is only rendered when the expander is tapped for the first time) after this change I could access an element like this:
var picker = BookingExpander.FindByName("PickupPicker") as Picker;
if (picker != null)
{
//do whatever you want
}
i want to create a checkbox in listview using xaml, after selecting the multiple checkbox click button to get all selected value.My code is :
<ContentPage.Content>
<ListView x:Name="ProductsListView">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Spacing="0">
<Label Text="{Binding retail_modified_item_id}"
TextColor="Blue" FontSize="13" />
<Label Text="{Binding name, StringFormat='Name :
{0:N}'}" TextColor="black" FontSize="10" />
<Label Text="{Binding retail_price,
StringFormat='Price : {0:N}'}"
TextColor="black" FontSize="10" />
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage.Content>
my output is;
output without checkbox
i tried some sample code from https://www.ignatiuz.com/blog/xamarin/button-check-box-with-list-item-in-xamarin-forms-listview/
but i'm getting input:checkbox not found
i am new to xamarin please give some sample code or link to do this
You can use Plugin.InputKit from Nuget.
Usage
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:xxx"
xmlns:input="clr-namespace:Plugin.InputKit.Shared.Controls;assembly=Plugin.InputKit"
x:Class="xxx.MainPage">
<ContentPage.Content>
<ListView x:Name="ProductsListView">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<ViewCell.View>
<StackLayout Spacing="0">
<Label Text="{Binding retail_modified_item_id}"
TextColor="Blue" FontSize="13" />
<Label Text="{Binding name, StringFormat='Name :
{0:N}'}" TextColor="black" FontSize="10" />
<Label Text="{Binding retail_price,
StringFormat='Price : {0:N}'}"
TextColor="black" FontSize="10" />
<input:CheckBox Text="xxx" Type="Check"/>
</StackLayout>
</ViewCell.View>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</ContentPage.Content>
</ContentPage>
I have written a content on implementing the multiselect listview in xamarin forms. Please check this : https://androidwithashray.blogspot.com/2018/03/multiselect-list-view-using-xamarin.html
Hope this helps.
Add/remove value to local collection using OnCheckChanged method.
I used this way:
<ListView>
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Orientation="Horizontal">
<Label Text="Some item" />
<CheckBox
IsChecked="true"
CheckedChanged="OnCheckedChanged"
HorizontalOptions="EndAndExpand"/>
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
If you need to have checkboxes inside a listview, you can use Xamarin.Forms.InputKi (https://github.com/enisn/Xamarin.Forms.InputKit)
Then I would define it like this inside a DataTemplate's ViewCell:
<input:CheckBox Text="Hello World I'm Option 2" Type="Check"/>
There are also Bindable properties and events which you can use depending on your scenario:
CheckChanged: (Event) Invokes when check changed.
CheckChangedCommand: (Command) Bindable Command, executed when check
changed.
Key: (int) A key you can set to define checkboxes as ID.
Text: (string) Text to display description
IsChecked: (bool) Checkbox checked situation. Works TwoWay Binding as
default.
Color: (Color) Color of selected check.
TextColor: (Color) Color of description text.
Type: (CheckType) Type of checkbox checked style.
(Check,Cross,Star,Box etc.)
I am using DottorPagliaccius repeater view thats nested inside another repeaterview. The command RSSFeedSelectedCommand doesnt work unless on top repeater, which in theory makes sense but how can i get it to work?
I have looked into using Converters and bindtoeventcommand but cant see to get them working.
<repeater:RepeaterView x:Name="MainRepeater" SeparatorHeight="25" ItemsSource={Binding Feeds}">
<repeater:RepeaterView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Spacing="10">
<Label Text="{Binding Title}" TextColor="Blue" />
<Label Text="{Binding Description}" TextColor="Red" FontSize="12" />
<repeater:RepeaterView x:Name="MainRepeater2" EmptyText="No elements" ShowSeparator="true" SeparatorHeight="2" SeparatorColor="Silver" ItemsSource="{Binding Items}" SelectedItemCommand="{Binding RSSFeedSelectedCommand}">
<repeater`enter code here`:RepeaterView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout Orientation="Horizontal">
<Image Source="{Binding Image.Url}"></Image>
<StackLayout Orientation="Vertical">
<Label Text="{Binding Title}" TextColor="Black" />
<Label Text="{Binding Description}" TextColor="Black" FontSize="12" />
</StackLayout>
</StackLayout>
</ViewCell>
</DataTemplate>
</repeater:RepeaterView.ItemTemplate>
</repeater:RepeaterView>
</StackLayout>
</ViewCell>
</DataTemplate>
</repeater:RepeaterView.ItemTemplate>
</repeater:RepeaterView>
The Repeater was trying to find the command in Feeds however exists in the ViewModel.
<repeater:RepeaterView x:Name="MainRepeater2" EmptyText="No elements" ShowSeparator="true" SeparatorHeight="2" SeparatorColor="Silver" ItemsSource="{Binding Items}" SelectedItemCommand="{Binding Source={x:Reference RSSPage}, Path=BindingContext.RSSFeedSelectedCommand}">
and you have to name the page:
<ContentPage x:Name="PageName" />
If my assumption is correct, your class structure should be something like,
ViewModel
|__List of Feeds
|__List of Items
|__RSSFeedSelectedCommand
So, DataContext of your inner repeater control (MainRepeater2) will be Feed. So, try with DataContext of outer repeater control. Like,
<repeater:RepeaterView x:Name="MainRepeater2" ItemsSource="{Binding Items}"
SelectedItemCommand="{Binding DataContext.RSSFeedSelectedCommand,
ElementName=MainRepeater}"/>
For Xamarin:
<repeater:RepeaterView x:Name="MainRepeater2" ItemsSource="{Binding Items}"
SelectedItemCommand="{Binding DataContext.RSSFeedSelectedCommand,
Source={x:Reference MainRepeater}}"/>
I have a list view with a DataTemplate and inside it I have a StackLayout that I need set its background but the color of it is inside a variable...When I programmatically set the background of an object using this variable color it works, but when I try to use "binding" in xaml it doesn't work and I can't get this stack programmatically because it's inside a data template...
I really need your answer..
Some help?
<ListView.ItemTemplate>
<DataTemplate>
<!--<DataTemplate.Triggers>
<DataTrigger Binding="{Binding fundoColor}" Value="4">
<Setter TargetName="produtos_stack_color" Property="Background" Value="LawnGreen" />
</DataTrigger>
</DataTemplate.Triggers>-->
<ViewCell>
<StackLayout x:Name="produtos_stack_color" BackgroundColor="{Binding fundoColor}" VerticalOptions="FillAndExpand" Margin="10,10,10,10">
<StackLayout Orientation="Horizontal" Padding="10,10,10,10" BackgroundColor="Black" HorizontalOptions="FillAndExpand">
<Image Source="{Binding imagem}" HeightRequest="80" HorizontalOptions="CenterAndExpand" WidthRequest="160" Aspect="Fill"/>
<StackLayout Orientation="Horizontal" BackgroundColor="Green" VerticalOptions="Center" HorizontalOptions="CenterAndExpand">
<Label Style="{StaticResource labelsfont}" Text="R$" FontSize="Medium" TextColor="White"/>
<Label Style="{StaticResource labelsfont}" Text="{Binding valor}" FontAttributes="Bold" FontSize="Large" TextColor="White"/>
</StackLayout>
</StackLayout>
<StackLayout Margin="0,0,0,10">
<Label Text="{Binding nome}" Style="{StaticResource labelsfont}" FontAttributes="Bold" FontSize="Medium" TextColor="White" VerticalOptions="StartAndExpand" HorizontalOptions="Center"/>
<ContentView BackgroundColor="Chartreuse" HorizontalOptions="FillAndExpand">
<Label Style="{StaticResource labelsfont}" Text="{Binding observacao}" TextColor="White" Margin="10,10,10,10" HorizontalOptions="Center" />
</ContentView>
</StackLayout>
</StackLayout>
</ViewCell>
</DataTemplate>
I heard about triggers...but I really don't know how it works exactly...
I need produtos_stack_color receive the color
My global variable in code behind...It is setted just in construct of my class
InitializeComponent();
fundoColor = Color.FromHex(this.categEscolhida.corFundo);
You can only bind with properties - so you will have to create a property in code-behind class.
public Color FundoColor { get { return fundoColor; } }
Secondly, in order to refer this property in XAML - you can use Reference extension, and specify parent as Source. For e.g.:
<StackLayout x:Name="produtos_stack_color"
BackgroundColor="{Binding FundoColor, Source={x:Reference ParentHost}}" ..>
And, make sure to set x:Name attribute in root node of your XAML. For e.g:
<ContentPage x:Name="ParentHost" .. />