Question

I want to change content of a Button in XAML using a DataTrigger. Conditionally I need to change the text of the button. However, if the Button initially have a text, the text is not changed. The only way to make it work is either not to set Content, or set it with a Trigger.

So if I have

<Button Content="Some text" />

the trigger doesn’t change the button text.

If I have

<Button />

or

<Button>
    <Button.Style>
        <Style TargetType="Button">
            <Setter Property="Content" Value="Some text" />
        </Style>
    </Button.Style>
</Button>

the trigger works.

Why?

Answer 1

This is because of DepedencyProperty precedence. see here: http://msdn.microsoft.com/en-us/library/ms743230.aspx

Local values have a higher precedence order than triggers. This means the local value will “take precedence” over the trigger value

When you set it in the Style it changes the precedence. A Trigger takes precedence over a Style Setter and this is why it works as you expect.