I am teaching myself Prism/Xamarin Forms and have struck an issue with the Navigation System in Prism.
I have two Views (MainPage and FirstPage) Registered in app.cs
protected override void RegisterTypes()
{
Container.RegisterTypeForNavigation<MainPage>("MainPage");
Container.RegisterTypeForNavigation<FirstPage>("FirstPage");
}
When I navigate to MainPage it works fine:
NavigationService.NavigateAsync("MainPage?title=MainPage");
However, when I navigate to FirstPage the app errors out with a "No Resource" Error.
Both Views and associated ViewModels are similarly coded:
<?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:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="PrismDemo.Views.MainPage"
Title="MainPage">
<StackLayout HorizontalOptions="Center" VerticalOptions="Center">
<Label Text="{Binding Title}" />
<Button Text="Navigate" Command="{Binding NavigateCommand}" />
</StackLayout>
</ContentPage>
<?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:prism="clr-namespace:Prism.Mvvm;assembly=Prism.Forms"
prism:ViewModelLocator.AutowireViewModel="True"
x:Class="PrismDemo.Views.FirstPage">
Title="FirstPage">
<StackLayout HorizontalOptions="Center" VerticalOptions="Center">
<Label Text="{Binding Title}" />
<Button Text="Back" Command="{Binding NavigateCommand}" />
</StackLayout>
</ContentPage>
using Prism.Commands;
using Prism.Mvvm;
using Prism.Navigation;
using System;
using System.Collections.Generic;
using System.Linq;
namespace PrismDemo.ViewModels
{
public class MainPageViewModel : BindableBase, INavigationAware
{
INavigationService _navigationService;
private string _title;
public string Title
{
get { return _title; }
set { SetProperty(ref _title, value); }
}
public DelegateCommand NavigateCommand { get; set; }
public MainPageViewModel(INavigationService navigationService)
{
_navigationService = navigationService;
NavigateCommand = new DelegateCommand(Navigate);
}
private void Navigate()
{
_navigationService.NavigateAsync("FirstPage");
}
public void OnNavigatedFrom(NavigationParameters parameters)
{
}
public void OnNavigatedTo(NavigationParameters parameters)
{
if (parameters.ContainsKey("title"))
Title = (string)parameters["title"] + " and Prism";
}
}
}
using Prism.Commands;
using Prism.Mvvm;
using Prism.Navigation;
using System;
using System.Collections.Generic;
using System.Linq;
namespace PrismDemo.ViewModels
{
public class FirstPageViewModel : BindableBase, INavigationAware
{
INavigationService _navigationService;
private string _title;
public string Title
{
get { return _title; }
set { SetProperty(ref _title, value); }
}
public DelegateCommand NavigateCommand { get; set; }
public FirstPageViewModel(INavigationService navigationService)
{
_navigationService = navigationService;
NavigateCommand = new DelegateCommand(Navigate);
}
private void Navigate()
{
_navigationService.GoBackAsync();
}
public void OnNavigatedFrom(NavigationParameters parameters)
{
}
public void OnNavigatedTo(NavigationParameters parameters)
{
if (parameters.ContainsKey("title"))
Title = (string)parameters["title"] + " and Prism";
}
}
}
Can anybody see where I am going wrong?
You have a misplaced '>' in your firstpage's xaml. Look at the end of the x:Class line and you will see the misplaced '>'. Get rid of it and it might work.
Related
UPDATE - Issue #1 is Solved, Issue#2 is still unsolved
You can view a very crude demonstration video of my issue at https://www.youtube.com/watch?v=5_6KJ0QJouM
I am building have a Xamarin.Forms app with an SQLite database using the MVVM design pattern and C#
When try to Save a record to the database from a View the update/save does not appear to be saving to the SQLite database or reflect in other Views.
I know the database Save method does work as I have created some dummy data when the application first loads (in App.xaml.cs) using the DeveloperData.cs file.
I have two issues.
(SOLVED) Issue 1 - Data not Saving to Database
when I call the Save command from the MerchandiserEditPage.xaml, which uses the MerchandiserEditPageViewModel.cs ViewModel, the record does not appear to save.
Issue 2 - Changes Reflecting in other Views
Once the updated data is saved to the database, how can I reflect that change in other views? After I Save a record from the MerchandiserEditPage that View is "Popped" off the stack and the user is returned to the MerchandiserProfileView. I want the updated data to be reflected in all other views on the stack. But this doesn't appear to be happening? (I tested this using hardcoded data and the same issue occurred, so problem is not directly related to issue 1)
There are many files in my project, that can be viewed/downloaded from my GitHub repository but I will concentrate on the following in this question.
MerchandiserEditPage.xaml (View)
MerchandiserProfilePage.xaml (View)
MerchandiserDatabase.cs (Database Functions)x
MerchandiserEditPageViewModel.cs x
View my GitHub repository for the full project.
MerchandiserDatabase.cs (Database Functions)
using SQLite;
namespace MobileApp.Database
{
public class MerchandiserDatabase
{
private static SQLiteConnection database = DependencyService.Get<IDatabaseConnection>().DbConnection();
private readonly static object collisionLock = new object();
public MerchandiserDatabase()
{
database.CreateTable<Models.Merchandiser>();
}
public static void SaveMerchandiser(Models.Merchandiser merchandiser)
{
lock (collisionLock)
{
if (merchandiser.Id != 0)
{
database.Update(merchandiser);
}
else
{
database.Insert(merchandiser);
}
}
}
}
}
MerchandiserEditPageViewModel.cs (ViewModel) UPDATED
using System;
using System.Collections.Generic;
using System.Text;
using Xamarin.Forms;
namespace MobileApp.ViewModels
{
public class MerchandiserEditPageViewModel : BaseViewModel
{
public string PageTitle { get; } = "Edit Merchandiser Profile";
public Command SaveCommand { get; set; }
private string name;
public string Name
{
get { return name; }
set
{
name = value;
OnPropertyChanged();
}
}
private string phone;
public string Phone
{
get { return phone; }
set
{
phone = value;
OnPropertyChanged();
}
}
private string email;
public string Email
{
get { return email; }
set
{
email = value;
OnPropertyChanged();
}
}
public MerchandiserEditPageViewModel(Models.Merchandiser selectedMerchandiser)
{
Name = selectedMerchandiser.Name;
Phone = selectedMerchandiser.Phone;
Email = selectedMerchandiser.Email;
SaveCommand = new Command( async ()=> {
selectedMerchandiser.Name = this.Name;
selectedMerchandiser.Phone = this.Phone;
selectedMerchandiser.Email = this.Email;
Database.MerchandiserDatabase.SaveMerchandiser(selectedMerchandiser);
await Application.Current.MainPage.Navigation.PopModalAsync();
});
}
}
}
MerchandiserEditPage.xaml (View)
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MobileApp.Views.MerchandiserEditPage">
<ContentPage.Content>
<StackLayout>
<!--Page Heading-->
<StackLayout Spacing="0">
<Label Text="{Binding PageTitle}"
Style="{StaticResource PageTitle}"/>
<BoxView HeightRequest="1" Color="LightGray" />
</StackLayout>
<!-- Merchandiser Profile -->
<StackLayout Margin="10">
<Label Text="Name"/>
<Entry Text="{Binding Name}"/>
<Label Text="Phone"/>
<Entry Text="{Binding Phone}"/>
<Label Text="Email"/>
<Entry Text="{Binding Email}"/>
<StackLayout Orientation="Horizontal"
HorizontalOptions="Center">
<Button Text="Cancel"
Clicked="CancelButton_Clicked"/>
<Button Text="Save"
Command="{Binding SaveCommand}"/>
</StackLayout>
</StackLayout>
</StackLayout>
</ContentPage.Content>
</ContentPage>
MerchandiserEditPage.xaml.cs (View - Code Behind)
public partial class MerchandiserEditPage : ContentPage
{
Models.Merchandiser SelectedMerchandiser { get; set; }
public MerchandiserEditPage (Models.Merchandiser selectedMerchandiser)
{
InitializeComponent ();
SelectedMerchandiser = selectedMerchandiser;
this.BindingContext = new ViewModels.MerchandiserEditPageViewModel(selectedMerchandiser);
}
async private void CancelButton_Clicked(object sender, EventArgs e)
{
await Navigation.PopModalAsync();
}
}
MerchandiserProfilePage.xaml (View - XAML)
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MobileApp.Views.MerchandiserProfilePage"
NavigationPage.HasNavigationBar="False">
<ContentPage.Content>
<StackLayout>
<!--Page Heading-->
<StackLayout Spacing="0">
<Label Text="{Binding PageTitle}"
Style="{StaticResource PageTitle}"/>
<BoxView HeightRequest="1" Color="LightGray" />
</StackLayout>
<!-- Merchandiser Profile -->
<StackLayout Margin="10">
<Label Text="Name"/>
<Entry Text="{Binding Name}"
IsEnabled="False"/>
<Label Text="Phone"/>
<Entry Text="{Binding Phone}"
IsEnabled="False"/>
<Label Text="Email"/>
<Entry Text="{Binding Email}"
IsEnabled="False"/>
<StackLayout Orientation="Horizontal"
HorizontalOptions="Center">
<Button Text="Back"
Clicked="BackButton_Clicked"/>
<Button Text="Edit"
Clicked="EditButton_Clicked"/>
</StackLayout>
<Button Text="Delete"
Command="{Binding DeleteCommand}"/>
</StackLayout>
</StackLayout>
</ContentPage.Content>
</ContentPage>
MerchandiserProfilePage.xaml.cs - (View - Code Behind)
public partial class MerchandiserProfilePage : ContentPage
{
private Models.Merchandiser SelectedMerchandister { get; set; }
public MerchandiserProfilePage (Models.Merchandiser selectedMerchandiser)
{
InitializeComponent ();
SelectedMerchandister = selectedMerchandiser;
this.BindingContext = new ViewModels.MerchandiserProfilePageViewModel(selectedMerchandiser);
}
async private void BackButton_Clicked(object sender, EventArgs e)
{
await Navigation.PopModalAsync();
}
async private void EditButton_Clicked(object sender, EventArgs e)
{
await Navigation.PushModalAsync(new Views.MerchandiserEditPage(SelectedMerchandister));
}
}
MerchandiserProfilePageViewModel.cs (ViewModel)
using System;
using System.Collections.Generic;
using System.Text;
using Xamarin.Forms;
namespace MobileApp.ViewModels
{
public class MerchandiserProfilePageViewModel : BaseViewModel
{
public string PageTitle { get; } = "Merchandiser Profile";
public Command DeleteCommand { get; }
private string name;
public string Name
{
get { return name; }
set
{
name = value;
OnPropertyChanged();
}
}
private string phone;
public string Phone
{
get { return phone; }
set
{
phone = value;
OnPropertyChanged();
}
}
private string email;
public string Email
{
get { return email; }
set
{
email = value;
OnPropertyChanged();
}
}
public MerchandiserProfilePageViewModel(Models.Merchandiser selectedMerchandiser)
{
Name = selectedMerchandiser.Name;
Phone = selectedMerchandiser.Phone;
Email = selectedMerchandiser.Email;
DeleteCommand = new Command( async()=> {
bool deleteConfirmed = await Application.Current.MainPage.DisplayAlert("Confirm Delete",$"Are you sure you want to delete {selectedMerchandiser.Name} as a Merchandiser?","Yes","No");
if (deleteConfirmed)
{
// TODO: Delete Merchandiser
await Application.Current.MainPage.Navigation.PopModalAsync();
}
});
}
}
}
you have a hardcoded set of data in your VM instead of loading it from the db
public MerchandisersPageViewModel()
{
//Merchandisers = new ObservableCollection<Models.Merchandiser>(Database.MerchandiserDatabase.GetMerchandisers());
Merchandisers = new ObservableCollection<Models.Merchandiser>()
{
new Models.Merchandiser { Id=1, Name="Barney Rubble", Phone="021 321 654", Email="barney#rubble.com"},
new Models.Merchandiser { Id=2, Name="Frank Grimes", Phone="022 456 789", Email="grimey#homersfriend.com"},
new Models.Merchandiser { Id=3, Name="Perry Platypus", Phone="023 789 456", Email="perry#agentp.com"},
};
}
Update:
in MerchandiserProfilePageViewModel, get rid of the properties for Name, Phone and EMail
then in MerchandiserProfilePage.xaml change the bindings
<Entry Text="{Binding SelectedMerchandiser.Name}" IsEnabled="False"/>
I'm trying to create a ContentPage that contains a TabView from XamarinCommunityToolkit.
Lets say that the Tabs define an ObservableCollection of Categories, and every TabViewItem should load a ContentView and passes a GroupId as an Argument / Property, and then I use that GroupId to filter Products list.
What's the best way to passe an argument to the ContentView ?
Update :
I've tried to use BindablePropertiy but, in the debugger, I can see the newValue recieved, but nothing shows in the Label :
MainPage.xaml
<?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:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-
compatibility/2006"
xmlns:xct="http://xamarin.com/schemas/2020/toolkit"
mc:Ignorable="d"
x:Class="mynamespace.Views.MainPage"
Title="{Binding Title}"
xmlns:local="clr-namespace:mynamespace.Views"
xmlns:vm="clr-namespace:mynamespace.ViewModels"
xmlns:model="clr-namespace:mynamespace.Models"
x:Name="MainPage">
<ContentPage.Content>
<xct:TabView Grid.Row="0"
TabStripPlacement="Top"
TabStripBackgroundColor="White"
TabStripHeight="48"
TabIndicatorColor="Orange"
TabIndicatorHeight="2"
TabItemsSource="{Binding Categories}">
<xct:TabView.TabViewItemDataTemplate>
<DataTemplate>
<Grid>
<Label Text="{Binding Name}"
FontAttributes="Bold"
VerticalOptions="Center"
Padding="6, 0"/>
</Grid>
</DataTemplate>
</xct:TabView.TabViewItemDataTemplate>
<xct:TabView.TabContentDataTemplate>
<DataTemplate>
<local:GroupView GroupId="{Binding Id}" />
</DataTemplate>
</xct:TabView.TabContentDataTemplate>
</xct:TabView>
</ContentPage.Content>
GroupView.xaml.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace mynamespace.Views
{
public partial class GroupView : ContentView
{
public string GroupId
{
get { return (string)GetValue(GroupIdProperty); }
set { SetValue(GroupIdProperty, value); }
}
public static readonly BindableProperty GroupIdProperty = BindableProperty.Create(
nameof(GroupId),
typeof(string),
typeof(GroupView),
"Default_V",
defaultBindingMode: BindingMode.OneWay,
propertyChanged: GroupIdChanged
);
private static void GroupIdChanged(BindableObject bindable, object oldValue, object newValue)
{
var control = (ProductListPage)bindable;
control.GroupId = newValue?.ToString();
}
public GroupView()
{
InitializeComponent();
BindingContext = this;
}
}
}
GroupView.xaml
<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="mynamespace.Views.GroupView">
<ContentView.Content>
<StackLayout>
<Label Text="{Binding GroupId}" /> <!-- Shows nothing -->
</StackLayout>
</ContentView.Content>
</ContentView>
Category class :
public class Category
{
private string id;
private string name;
private string description;
public string Id { get => id; set => id = value; }
public string Name { get => name; set => name = value; }
public string Description { get => description; set => description = value; }
}
ProductListViewModel.cs
public class ProductListViewModel : BaseViewModel
{
public string GroupId { get; set; }
public ProductListViewModel()
{
}
public ProductListViewModel(string groupId)
{
GroupId = groupId;
}
}
Update :
[0:] Binding: 'GroupId' property not found on 'mynamespace.Models.Category', target property: 'Xamarin.Forms.Label.Text'
Don't assign bindings internally inside custom controls. You could do like this:
public partial class GroupView : ContentView
{
GroupViewModel _viewModel;
public string GroupId
{
get { return (string)GetValue(GroupIdProperty); }
set { SetValue(GroupIdProperty, value); }
}
public static readonly BindableProperty GroupIdProperty = BindableProperty.Create(
nameof(GroupId),
typeof(string),
typeof(GroupView),
"Default_V",
defaultBindingMode: BindingMode.OneWay,
propertyChanged: GroupIdChanged
);
private static void GroupIdChanged(BindableObject bindable, object oldValue, object newValue)
{
var control = (GroupView)bindable;
control.GroupId = (string)newValue;
control.label.Text = control.GroupId;
}
public GroupView()
{
InitializeComponent();
}
}
then in xaml:
<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="mynamespace.Views.GroupView">
<ContentView.Content>
<StackLayout>
<Label x:Name="label" />
</StackLayout>
</ContentView.Content>
</ContentView>
I dont know how is it called.
I need to create something that works this way:
Do button, when you click button under button you have list and you can choos one option. List should be button's width.
You can find it in aplication to choose for example language of country.
Do Xamarin built-in something to create this? Or can someone show me how implement this?
Or you could roll your own in Forms, something like:
ImagePickerDropDown.xaml:
<?xml version="1.0" encoding="UTF-8"?>
<ContentView
xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="ImagePickerDropdownSample.ImagePickerDropdown"
x:Name="imagePickerDropDown" >
<ContentView.Content>
<StackLayout>
<ImageButton x:Name="mainButton"
Source="{Binding Source={x:Reference imagePickerDropDown}, Path=SelectedImage}"
Clicked="ImageClicked" />
<StackLayout x:Name="stackView"
BindableLayout.ItemsSource="{Binding Source={x:Reference imagePickerDropDown}, Path=Images}"
IsVisible="False">
<BindableLayout.ItemTemplate>
<DataTemplate>
<StackLayout>
<ImageButton Source="{Binding .}" Clicked="ImageSelected"/>
</StackLayout>
</DataTemplate>
</BindableLayout.ItemTemplate>
</StackLayout>
</StackLayout>
</ContentView.Content>
</ContentView>
ImagePickerDropDown.xaml.cs:
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using Xamarin.Forms;
namespace ImagePickerDropdownSample
{
public partial class ImagePickerDropdown : ContentView
{
public ImagePickerDropdown()
{
InitializeComponent();
}
private void ImageSelected(object sender, EventArgs e)
{
var imageSource = (sender as ImageButton).Source;
SelectedImage = imageSource;
mainButton.IsEnabled = true;
stackView.IsVisible = false;
}
private void ImageClicked(object sender, EventArgs e)
{
mainButton.IsEnabled = false;
stackView.IsVisible = true;
}
public static readonly BindableProperty SelectedImageProperty =
BindableProperty.Create(nameof(SelectedImage), typeof(ImageSource), typeof(ImagePickerDropdown), null);
public ImageSource SelectedImage
{
get
{
return (ImageSource)GetValue(SelectedImageProperty);
}
set
{
SetValue(SelectedImageProperty, value);
}
}
public static readonly BindableProperty ImagesProperty =
BindableProperty.Create(nameof(Images), typeof(ObservableCollection<ImageSource>), typeof(ImagePickerDropdown), null);
public ObservableCollection<ImageSource> Images
{
get
{
return (ObservableCollection<ImageSource>)GetValue(ImagesProperty);
}
set
{
SetValue(ImagesProperty, value);
}
}
}
}
Using it XAML:
<?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:d="http://xamarin.com/schemas/2014/forms/design"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Class="ImagePickerDropdownSample.MainPage"
xmlns:local="clr-namespace:ImagePickerDropdownSample"
Padding="0,50,0,0"
BackgroundColor="Black">
<StackLayout
x:Name="mainLayout">
<Label Text="Welcome to Xamarin.Forms!"
HorizontalOptions="Center"
VerticalOptions="Start"
TextColor="White"/>
<local:ImagePickerDropdown SelectedImage="{Binding SelectedImage}"
Images="{Binding Images}"
WidthRequest="50"
HorizontalOptions="Center"
BackgroundColor="Black"/>
</StackLayout>
</ContentPage>
Using it code behind:
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Threading.Tasks;
using Xamarin.Forms;
namespace ImagePickerDropdownSample
{
// Learn more about making custom code visible in the Xamarin.Forms previewer
// by visiting https://aka.ms/xamarinforms-previewer
[DesignTimeVisible(false)]
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
Images = new ObservableCollection<ImageSource>();
Images.Add(new FileImageSource() { File = "image1.png" });
Images.Add(new FileImageSource() { File = "image2.png" });
Images.Add(new FileImageSource() { File = "image3.png" });
SelectedImage = Images[0];
BindingContext = this;
}
ImageSource _selectedImage;
public ImageSource SelectedImage
{
get
{
return _selectedImage;
}
set
{
if (_selectedImage != value)
{
_selectedImage = value;
OnPropertyChanged(nameof(SelectedImage));
}
}
}
ObservableCollection<ImageSource> _images;
public ObservableCollection<ImageSource> Images
{
get
{
return _images;
}
set
{
if (_images != value)
{
_images = value;
OnPropertyChanged(nameof(Images));
}
}
}
}
}
Use a Spinner .. basically you need to first create an ArrayAdapter then attach the ArrayAdapter to a Spinner :
//we need a List of some type because the ArrayAdapter takes one as param
var items = new List<string>() {"one", "two", "three"};
//instantiate the ArrayAdapter with context, your Resource is a layout, items is the List
var adapter = new ArrayAdapter<string>(this, Android.Resource.Layout.SimpleSpinnerItem, items);
//then instantiate your spinner
var spinner = FindViewById<Spinner>(Resource.Id.spinner);
//and attach the adapter to the spinner like this
spinner.Adapter = adapter;
from #Aaron He
Create android spinner dynamically in Xamarin
I have a simple app on Xamarin (a to-do list) which purpose is to dynamically create and remove items from a list. I am using ObservableCollection for the list. I spent a ton of time researching about this but I could not get it working.
Right now my app can add items to the list and display it in the main form. Now I want it to delete the corresponding items from the list with a click of a button.
Here is my code:
MainPage.xaml
<?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:App3"
x:Class="App3.MainPage">
<ContentPage.ToolbarItems>
<ToolbarItem Text="Add" Clicked="addnewitem"/>
</ContentPage.ToolbarItems>
<ContentPage.BindingContext>
<local:viewmod/>
</ContentPage.BindingContext>
<StackLayout>
<Editor x:Name="txtboxNAME"></Editor>
<ListView ItemsSource="{Binding Tasks}" HasUnevenRows="True" x:Name="itemListView">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<Frame>
<StackLayout>
<Editor Text="{Binding Taskname}"/>
<Switch/>
<Button Text="Delete" CommandParameter="{Binding ItemName}" Clicked="DeleteClicked">
</Button>
</StackLayout>
</Frame>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackLayout>
</ContentPage>
MainPage.xaml.cs (The code behind the MainPage form)
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Xamarin.Forms;
namespace App3
{
public partial class MainPage : ContentPage
{
static int itemid = 0;
public MainPage()
{
InitializeComponent();
BindingContext = new viewmod();
}
private void addnewitem(object sender, EventArgs e)
{
var vm = BindingContext as viewmod;
string itemnameval = "item_" + itemid.ToString();
vm.AddItems(this.txtboxNAME.Text, itemnameval);
itemid++;
}
private void DeleteClicked(object sender, EventArgs e) // Item should be deleted from the list
{
// This does not work
var itemsender = (Xamarin.Forms.Button)sender;
var item = itemsender?.BindingContext as Task;
var vm = BindingContext as viewmod;
vm?.RemoveCommand.Execute(item);
//vm.Tasks.Remove(item); // conversion error
// This does not work either. "allItems" is not defined.
TaskClass listitem = (from itm in allItems
where itm.ItemName == item.CommandParameter.ToString()
select itm).FirstOrDefault<TaskClass>();
allItems.Remove(listitem);
}
}
}
TaskClass.cs
namespace App3
{
class TaskClass
{
public string Taskname { get; set; }
public string ItemName { get; set; }
}
}
viewmod.cs
using System.Collections.ObjectModel;
using Xamarin.Forms;
namespace App3
{
class viewmod
{
public ObservableCollection<TaskClass> Tasks { get; set; } = new ObservableCollection<TaskClass>();
public viewmod()
{
}
public void AddItems(string taskn, string taskid)
{
Tasks.Add(new TaskClass { Taskname = $"{taskn}", ItemName=$"{taskid}" });
}
public void DelItem(TaskClass task)
{
Tasks.Remove(task);
}
public Command<TaskClass> RemoveCommand
{
get
{
return new Command<TaskClass>((task) =>
{
Tasks.Remove(task);
});
}
}
}
}
modify your XAML first = the "." syntax passes the entire bound object
<Button Text="Delete" CommandParameter="{Binding .}" Clicked="DeleteClicked" />
then in your code behind
private void DeleteClicked(object sender, EventArgs e)
{
var itemsender = (Xamarin.Forms.Button)sender;
var item = (TaskClass)itemsender?.CommandParameter;
// it would be much cleaner to keep a ref to your VM in your page
// rather than continually casting it from BindingContext
var vm = BindingContext as viewmod;
vm.Tasks.Remove(item);
}
I'm using a nuget package called Refractored.XamForms.PullToRefresh.
So my MainPage.Xaml Has:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:local="clr-namespace:TheOctant"
xmlns:controls="clr-namespace:Refractored.XamForms.PullToRefresh;assembly=Refractored.XamForms.PullToRefresh"
x:Class="TheOctant.MainPage">
<StackLayout>
<ScrollView>
<controls:PullToRefreshLayout x:Name="ptrl" RefreshCommand="{Binding UponRefresh}" RefreshColor="Blue">
<local:ZoomWebView x:Name="webview" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand"></local:ZoomWebView>
</controls:PullToRefreshLayout>
</ScrollView>
</StackLayout>
</ContentPage>
So look at RefreshCommand="{Binding UponRefresh}", I'm trying to bind it to a c# function in MainPage.Xaml.cs
So Here's my failed attempt in MainPage.Xaml.cs:
namespace TheOctant
{
public partial class MainPage : ContentPage
{
public MainPage()
{
InitializeComponent();
}
public void UponRefresh()
{
webview.Source = "http://www.google.com";
}
}
}
But it doesn't work. Am I doing this correctly?
No. As the name implies, RefreshCommand needs to be a Command
public ICommand UponRefresh
{
get {
return new Command(async () =>
{
webview.Source = "http://www.google.com";
});
}
}