Is there a simple way to specify a WPF databinding where the path is one "level" up?
This example is a admittedly a little contrived but I am doing something similar. Let's say I have the following simple classes:
public class Person
{
public string Name { get; set; }
public List<Alias> Aliases { get; set; }
}
public class Alias
{
public string AliasName { get; set; }
}
And let's say that I have Xaml with a LayoutRoot grid, and a DataGrid where I want to access the Name property within the DataGrid instead of the Aliases properties like in the second column here:
<Grid x:Name="LayoutRoot" DataContext="PersonInstance">
<DataGrid ItemsSource="{Binding Aliases}">
<DataGrid.Columns>
<data:DataGridTextColumn Header="AliasName" Binding="{Binding AliasName, Mode=TwoWay}"/>
<data:DataGridText开发者_运维知识库Column Header="Name" Binding="{Binding ../Name, Mode=TwoWay}"/>
</DataGrid.Columns>
</DataGrid>
</Grid>
That is intuitively how I would attempt to bind the name, but needless to say that looks stupid. Is there something like that when specifying a path, or are you forced to get a relative source up to the LayoutRoot data context. If you have to, what's the most efficient way?
This should work for you :
<DataGridTextColumn Header="Name"
Binding="{Binding RelativeSource={RelativeSource
FindAncestor,
AncestorLevel=3,
AncestorType={x:Type Grid},
Path=DataContext.Name}"/>
You can use any of the following :
To make the source element equal the closest parent of a given type:
{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type
desiredType}}}
To make the source element equal the nth closest parent of a given type:
{Binding RelativeSource={RelativeSource FindAncestor,
AncestorLevel=n, AncestorType={x:Type desiredType}}}
To make the source element equal the previous data item in a data-bound collection:
{Binding RelativeSource={RelativeSource PreviousData}}
I think there is no better way to do this than using relative source up the tree. You could rewrite your model (for example, add a reference to parent Person
from Alias
) but that's hardly better approach.
From performance prospective I never found bottlenecks in relative source bindings. There's always something else that keeps your app away from rocket speed.
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