WPF DataContext. Taking from another class

Question

having general DataContext taken from class SearchByID there's a need to take a separate DataContext from another class, say, testClass.

XAML example:

<Window.DataContext>
        <model:SearchById />
 </Window.DataContext>

<Grid>

<TextBlock Text="{Binding Description}">
<Texblock.DataContext>
<model: testClass/>
</TextBlock.DataContext>
</TextBlock>


</Grid>

There are no fails, IntelliSens sees all the Properties. But the TextBlock is blank.

any ideas please.

It doesn't seem to make sense to assign a testClass instance to the DataContext of a TextBlock, only to show its Description property, which could only be initialized once in the testClass instance. You may perhaps better bind directly to a static property. It is unclear what you are actually trying to achieve. — Clemens, Sep 23 '20 at 17:23

Peter Boone · Answer 1 · 2020-09-23T17:12:30.937

1

One idea, is the Description a property or a field?

A Property will work:

public class TestClass
{
    public string Description { get; set; }
    public TestClass()
    {
        Description = "Test";
    }
}

A field won't:

public class TestClass
{
    public string Description;
    public TestClass()
    {
        Description = "Test";
    }
}

MainWindow.xaml

<TextBlock Text="{Binding Description}"
           Background="Yellow" 
           HorizontalAlignment="Center"
           VerticalAlignment="Center">
    <TextBlock.DataContext>
        <local:TestClass />
    </TextBlock.DataContext>
</TextBlock>

Result:

edited Sep 23 '20 at 17:12

answered Sep 23 '20 at 15:58

Peter Boone

1,193
1
12
20

the "Description" is a property of class testClass. – Bolt Blacksmith Sep 23 '20 at 16:26
You have mentioned above "fields". If "Description" is a field. Won't it work. Or? – Bolt Blacksmith Sep 23 '20 at 17:02
Sorry, should have been clearer. A field (the second example) won't work. – Peter Boone Sep 23 '20 at 17:13
I have understood what you meant. A question: why so? What a reason? – Bolt Blacksmith Sep 23 '20 at 17:15
1

@Bolt data binding works with public properties only. If Description is one, and it is initialized appropriately, your code should work. You would have to provide more details in your question, i.e. show the declaration and initialization of the property. – Clemens Sep 23 '20 at 17:19

WPF DataContext. Taking from another class

1 Answers1