Accessing a resource via codebehind in WPF

Question

I have a custom collection defined in my window resources as follows (in a Sketchflow app so the window is actually a UserControl):

<UserControl.Resources>
    <ds:MyCollection x:Key="myKey" x:Name="myName" />
</UserControl.Resources>

I want to be able to refer to this collection in the codebehind, which I expected would be by the x:Name, but I can't seem to access it.

I can get a reference to it using

myRef = (MyCollection) this.FindName("myKey");

but this seems hackish. Is this bad practice, and what would be better? Thanks :)

score 92 · Accepted Answer · edited Nov 03 '16 at 22:41

92

You should use System.Windows.Controls.UserControl's FindResource() or TryFindResource() methods.

Also, a good practice is to create a string constant which maps the name of your key in the resource dictionary (so that you can change it at only one place).

edited Nov 03 '16 at 22:41

Alexander Abakumov

12,301
14
79
125

answered Jan 22 '10 at 14:33

japf

6,428
2
31
30

8

You can use: Application.Current.FindResource(errorColorResourceName) as MyCollection or this.FindResource("RainbowBrush") as MyCollection. It depends on the context. – Tal Segal Oct 27 '16 at 09:24
13

Can you elaborate on "Also, a good practice is to create a string constant which maps the name of your key in the resource dictionary (so that you can change it at only one place)." ? Where would such a string constant go that would change the XAML key as well as the C# code behind? – Mike Christiansen Oct 29 '18 at 14:36
1

+1 for > Can you elaborate on "Also, a good practice is to create a string constant which maps the name of your key in the resource dictionary (so that you can change it at only one place)." ? Where would such a string constant go that would change the XAML key as well as the C# code behind? – tolache Apr 06 '21 at 10:15

score 29 · Answer 2 · answered Jan 22 '10 at 14:34

29

You may also use this.Resources["mykey"]. I guess that is not much better than your own suggestion.

answered Jan 22 '10 at 14:34

Jakob Christensen

14,561
1
50
81

1

This is for Windows 8 Store Apps. – cederlof Mar 06 '14 at 09:12
3

@cederlof, you can use this with WPF too. – Jan 29 '16 at 13:37
1

This will not work if the resource is in another file, for instance a theme color. FindResource is the way to go. – John C Dec 06 '19 at 16:21

score 21 · Answer 3 · edited Oct 28 '14 at 13:32

21

Not exactly direct answer, but strongly related:

In case the resources are in a different file - for example ResourceDictionary.xaml

You can simply add x:Class to it:

<ResourceDictionary x:Class="Namespace.NewClassName"
                    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
    <ds:MyCollection x:Key="myKey" x:Name="myName" />
</ResourceDictionary>

And then use it in code behind:

var res = new Namespace.NewClassName();
var col = res["myKey"];

edited Oct 28 '14 at 13:32

Nicke Manarin

2,603
1
30
64

answered Jun 18 '14 at 12:49

itsho

4,305
3
43
64

12

+1, but to be able to find resources using it's key I had to call `res.InitializeComponent()` before attempting to access the key otherwise the object would show no keys and the call to `res["myKey"]` would return null. – Stephen Ross Dec 17 '15 at 10:22
Wow that's awesome... I never knew you could do that and it just solved a problem for me quick and easy! I did need to call InitializeComponent() like @StephenRoss said but other than that works like a charm. – sfaust Sep 25 '17 at 19:06
A perfect solution to use from `Converters` – Brains May 15 '19 at 08:09

score 10 · Answer 4 · answered Jul 27 '18 at 20:26

10

If you want to access a resource from some other class (i.g. not a xaml codebehind), you can use

Application.Current.Resources["resourceName"];

from System.Windows namespace.

answered Jul 27 '18 at 20:26

Arsinclair

1,104
16
29

This is useful if you need to access the resource from a static constructor or method, and therefore don't have the ability to call `FindResource` or `TryFindResource`. – Steven Rands May 14 '20 at 11:10

score 8 · Answer 5 · answered Oct 21 '15 at 23:00

You can use a resource key like this:

<UserControl.Resources>
    <SolidColorBrush x:Key="{x:Static local:Foo.MyKey}">Blue</SolidColorBrush>
</UserControl.Resources>
<Grid Background="{StaticResource {x:Static local:Foo.MyKey}}" />

public partial class Foo : UserControl
{
    public Foo()
    {
        InitializeComponent();
        var brush = (SolidColorBrush)FindResource(MyKey);
    }

    public static ResourceKey MyKey { get; } = CreateResourceKey();

    private static ComponentResourceKey CreateResourceKey([CallerMemberName] string caller = null)
    {
        return new ComponentResourceKey(typeof(Foo), caller); ;
    }
}

Note that this depends on the type of key. E.g. a key in a `DataTemplate` is of type `DataTemplateKey`. — Mike de Klerk, Nov 01 '16 at 10:04

score 1 · Answer 6 · answered Nov 24 '19 at 02:24

1

I got the resources on C# (Desktop WPF W/ .NET Framework 4.8) using the code below

{DefaultNamespace}.Properties.Resources.{ResourceName}

answered Nov 24 '19 at 02:24

Ranier Jardim

31
2

score 0 · Answer 7 · answered Jan 24 '22 at 21:39

0

A nice clean example from Microsoft documents makes it simple:

private void myButton_Click(object sender, RoutedEventArgs e)
{
  Button button = (Button)sender;
  button.Background = (Brush)this.FindResource("RainbowBrush");
}

answered Jan 24 '22 at 21:39

Miyamoto Musashi

424
6
14

Accessing a resource via codebehind in WPF

7 Answers7

Linked