How to set ItemsSource of ListView?

Question

Here I have defined my data myListOfEmployeeObjects:

public class App : Application
{
    public List<Employee> myListOfEmployeeObjects;

    public App ()
    {
        Employee emp1 = new Employee () {
            FirstName = "Max",
            LastName = "Mustermann",
            Twitter = "@fake1"
        };
        Employee emp2 = new Employee () {
            FirstName = "Evy",
            LastName = "Mustermann",
            Twitter = "@fake2"
        };
        myListOfEmployeeObjects = new List<Employee> {
            emp1, emp2
        };
        MainPage = new NavigationPage (new EmployeeListPage ());
    }
}

Than I have my XAML where I set the ItemsSource:

<ListView x:Name="listView"
                IsVisible="false"
                ItemsSource="{x:Static local:App.myListOfEmployeeObjects}"
                ItemSelected="EmployeeListOnItemSelected">

Should this work? Because I get

Xamarin.Forms.Xaml.XamlParseException: Type App not found in xmlns

public partial class EmployeeListPage : ContentPage {

    private ListView listView;

    private void InitializeComponent() {
        this.LoadFromXaml(typeof(EmployeeListPage)); // here the exception is thrown
        listView = this.FindByName <ListView>("listView");
    }
}

How can I set the ItemsSource of my XAML?

Edit:

Now I tried the suggestion from user2425632 and it works if I do the following changes:

1. Adding xmlns:local="clr-namespace:HelloXamarinFormsWorld;assembly=HelloXamarinFormsWorld" to my XAML file

It now looks like the following

<?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:HelloXamarinFormsWorld;assembly=HelloXamarinFormsWorld"
             x:Class="HelloXamarinFormsWorld.EmployeeListPage"
             Title="Employee List">
    <ContentPage.Content>

Of course you have to change the names so that it suits to your project.

2. Showing list view

I removed the IsVisible and the ItemSelected.

<ListView ItemsSource="{x:Static local:App.myListOfEmployeeObjects}">

3. Make everything static

It has to be static, otherwise you get

No static member found for local:App.myListOfEmployeeObjects

public static List<Employee> myListOfEmployeeObjects { private set; get; }

public static void GetAllEmployees(){
    Employee emp1 = new Employee () {
        FirstName = "Max",
        LastName = "Mustermann",
        Twitter = "@fake1"
    };
    Employee emp2 = new Employee () {
        FirstName = "Eva",
        LastName = "Mustermann",
        Twitter = "@fake2"
    };
    myListOfEmployeeObjects = new List<Employee> {
        emp1, emp2
    };
}

public App ()
{
    GetAllEmployees ();
    MainPage = new NavigationPage (new EmployeeListPage ());
}

Solution 1

So I haven't actually gotten around to doing this myself but from reading the documentation I have a suggestion which may be worth you trying.

ItemsSource="{x:Static local:App.myListOfEmployeeObjects}"

In your xaml you've said that the source is static but looking at your .cs file it isn't. Try the following:

public static List<Employee> myListOfEmployeeObjects { private set; get; }

and then try and set the object using a static function, eg.:

static App() {
    myListOfEmployeeObjects = something;
}

Then the list should be viewable on the page.

I used the following links which you may find useful:

Xamarin documentation on data-binding

Example cs code

Example xaml code

Hope that helps.

Solution 2

I think I have the solution for your problem. I had the same issue and I added this line in EmployeeListPage.xaml :

xmlns:local="clr-namespace:YourNamespace;assembly=YourAssembly"

You'll get the name of assembly in the properties of your project and the namespace in any page.cs

Comments

[testing]

Thanks for your response. I'll try it out. Would it be possible to use a normal list as I did? Or can this only be done with ObservableCollections? Here only a static IEnumerable has been used ...

[Sonhja]

I think bindings will be only seen with ObservableCollections. Try this code, and if it works, try to change it with a regular list as you have. They are not difficult. The same like lists :)

[testing]

Now I tried your code (see here). Some things are not clear for me. 1. What is InitializeComponent()? 2. What is DataContext? I commented them out because otherwise I get an build error. public event PropertyChangedEventHandler PropertyChanged; was missing and I added it. 3. What is my main window? My main window is not in XAML. Perhaps are you talking from WPF, because the Xamarin version does look different. I removed it from the .xaml. When I try running the code I get Object reference not set to an instance of an object.

[Sonhja]

The InitializeComponent() is auto-generated when you first create an WPF project, so you don't have to modify or write it. Just look for it and add the DataContext line after. The DataContext tells the application that, any data change, will be shared in the same context. Anyways... can you post full code please? Add .xaml and .cs.

[testing]

I think WPF is different than the Xamarin approach. DataContext = BindingContext? Nevertheless, .cs, .xaml. Sorry, I can't use many other services because the webfilter here blocks everything ...