I have an attached property defined as follows:
Where FilterGrid is an overridden DataGrid and eFilterType is an Enum defined in the same class.
public static readonly DependencyProperty FilterTypeProperty = DependencyProperty.RegisterAttached( " FilterType" , typeof (eFilterType), typeof (FilterGrid), new PropertyMetadata((eFilterType)(-1), new PropertyChangedCallback(OnFilterTypeChanged))); public static eFilterType GetFilterType(DependencyObject control) return (eFilterType)control.GetValue(FilterTypeProperty); public static void SetFilterType(DependencyObject control, eFilterType Value) control.SetValue(FilterTypeProperty, Value); I set this attached property on the Column when defining the Column as follows:
< DataGridTextColumn Header =" Surname" Binding =" {Binding Surname}" ctl:FilterGrid.FilterType =" TextFilter" >
I then have a style defined in Generic.xaml for the FilterGrid which also sets a style for the DataGridColumnHeader
The problem I'm having is getting back the FilterType attached property that was set on the DataGridColumnHeader.Column . In the Header's style I have a DataTrigger that uses a converter as follows:
< DataTrigger Binding =" {Binding RelativeSource={RelativeSource Self},Converter={StaticResource HeaderToFilterTypeConverter}}" Value =" TextFilter" > < Setter Property =" Background" Value =" Blue" / > < /DataTrigger >
If I return eFilterType.TextFilter from my converter it works fine, however, I need to return the FilterType attached property from the header's Column property.
The problem is that Column is always null when my converter gets the header.
I have tried setting the attached FilterType property to the header when the OnFilterTypeChanged event is raised for setting it on the column, but I cannot find the header from the Column either, I did try the solution given here , but the problem there is that I cannot get to the DataGrid associated with the Column (setting it to this doesn't work as it needs to change to a static method)
I am doing it this way as I do not know how else to aproach this, basically I want to set a FilterType on the Column and have a Trigger (defined in the Style for the header) respond based on what the value was set to
Any help would be appreciated. I found a way to do what I wanted, not sure if it's the best way though. Here is what I ended up doing:
I made a custom control that will be used in the DataGridColumnHeader as a filter control. This control has the following properties:
/// < summary > /// Filter type for each instance of the FilterControl /// < /summary > public static readonly DependencyProperty FilterProperty = DependencyProperty.Register( " Filter" , typeof (eFilterType), typeof (FilterControl), new PropertyMetadata((eFilterType)(-1))); public eFilterType Filter get { return (eFilterType)GetValue(FilterProperty); } set { SetValue(FilterProperty, value ); } /// < summary > /// Column property used to get to the FilterType attached property to be able to set the FilterProperty /// < /summary > public static readonly DependencyProperty ColumnProperty = DependencyProperty.Register( " Column" , typeof (DataGridColumn), typeof (FilterControl), new PropertyMetadata( null , new PropertyChangedCallback(ColumnChanged))); public DataGridColumn Column get { return (DataGridColumn)GetValue(ColumnProperty); } set { SetValue(ColumnProperty, value ); } /// < summary > /// FilterType attached property - used on column definition from the outside application /// < /summary > public static readonly DependencyProperty FilterTypeProperty = DependencyProperty.RegisterAttached( " FilterType" , typeof (eFilterType), typeof (FilterControl), new PropertyMetadata((eFilterType)(-1))); public static eFilterType GetFilterType(DataGridColumn Column) return (eFilterType)Column.GetValue(FilterTypeProperty); public static void SetFilterType(DataGridColumn Column,eFilterType Type) Column.SetValue(FilterTypeProperty, Type); The control has a callback when the Column property changes, it then sets the FilterProperty for the control
public static void ColumnChanged(DependencyObject o, DependencyPropertyChangedEventArgs e) if (e.NewValue is DataGridColumn) DataGridColumn Col = (DataGridColumn)e.NewValue; eFilterType Type = (eFilterType)Col.GetValue(FilterTypeProperty); o.SetValue(FilterProperty, Type); In the Generic.xaml I bound the Column property to the DataGridHeader's Column property like this:
< local:filtercontrol column =" {Binding <br mode=" hold =" /> RelativeSource={RelativeSource <br mode=" xmlns:local =" #unknown" > < /local:filtercontrol >
All this enables me to use a Trigger from the FilterControl's template like this:
< controltemplate.triggers > < trigger property =" Filter" value =" BoolFilter" > < setter property =" Background" value =" Red" > TargetName="tbText"/> < /setter > < /trigger > < /controltemplate.triggers >
That is what I have currently, please let me know if there is a better way.

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