I would like to freeze a DataGridTextColumn in WPF but it looks like there is not a property for that in that class specifically. However, looking at the source for the WPFToolkit, there is a IsFrozen in DataGridColumn which is the parent of DataGridBoundColumn, which is the parent of DataGridTextColumn. So...why isn't that property available?
I believe this property is not available because it's a read only. Since frozen columns are always the leftmost columns in display order you can use datagrid's FrozenColumnCount property to freeze whatever number of columns you need. You can set it up in xaml or chage it in you code. See documentation for more details here
Related
I am coming from programming with WinForms and now start to change into WPF. In WinForms I could easily bind a DataGrid before Runtime, to adjust the columns without coding everything.
The WPF-Datagrid has the property "ItemsSource", but I don't understand how to bind it in editor. I have already a DataSource which refers to a SQL-Database, but it will not be shown in the property window.
How to do this?
Screenshot
you have to expose your collection as a public property
make it visible in the xaml (namespace include)
set up your DataContext correctly
create the binding in XAML and set up the columns, like here
If you want to see the changes in your collection online, you have to use ObservableCollection<>
How is it possible to do multivalue binding in Silverlight?
I have to determine the Visibility of a Silverlight DataGrid column depending on the value present as part of Datacontext and other one from the QueryString.
I use MVVM Model of silverlight 5 and my plan is currently to define a property for querystring in code behind that can be binded to row visibility. But my problem clearly here is to pass multiple values for the IValueConverter implementation.
Can anyone provide a simple example to solve my problem?
Multi binding is not supported out of the box in Silverlight.
But with the introduction of customer markup extensions in Silverlight 5, this can be achieved.
There's a good example on code project: http://www.codeproject.com/Articles/286171/MultiBinding-in-Silverlight-5.
Alternatively, in this particular example you can have public boolean a property in your view model which uses the QueryString Value along with the other value you are concerned in DataContext and decides whether the column needs to be visible or not. You can then databind this property to your column's IsVisible property. (Along with a value converter which returns Visbility.Visble /Visibility.Collapsed depending on the value of the boolean property value)
On button click, Updating the ListBox ItemsSource collection.
For 4 or 5 clicks its working fine but afterwards it throws an exception as '[Unknown]' property does not point to a DependencyObject in path '(0).(1)[1].(2)'
I googled it & find the reason for it.
"The ElementControl overrides PrepareContainerForItemOverride and
calls PrepareModel to insert a mesh into _modelContainer for each
Item. Later in ElementFlow.BuildTargetPropertyPath (which is called
via ElementFlow.SelectItemCore -> LayoutBase.SelectElement ->
ElementFlow.PrepareTemplateStoryboard) it is assumed that such a mesh
has been inserted into _modelContainer. This exception occurs when the
mesh has not been inserted into _modelContainer. WPF calls
PrepareContainerForItemOverride on ApplyTemplate. This is only done
once. Items added later are never processed like that. "
So please provide me a solution to overcome it.
It seems like maybe there is an item in your " itemsource collection" that is not of the right type, or does not contain one of the properties that your listbox itemstemplate is looking for. Or, perhaps if you have different classes in your collection, one of them may not have the property you are looking for as a DependencyProperty. If it is just a plain property, it may not work correctly.
Check all object types that are going into your itemssource collection and make sure they all have DependencyProperties that are named what the itemstemplate is looking for.
What's the best method of dynamically specifying DataGrid columns in the Silverlight DataGrid control at runtime following the MVVM pattern?
What I'd like to do would be bind the "DataGrid.Columns" property to a property in my ViewModel so that, if the user adds/removes columns, I simply update the ViewModel property and the DataGrid would change. Problem is, the "DataGrid.Columns" property can't be bound to (I don't think).
Because this property isn't available nor is the DataGrid control itself available at the ViewModel level, my current approach is to step outside of the MVVM pattern for this particular implementation and capture certain events in View's code-behind using MVVM Light's Messenger class and then talk directly with the DataGrid control to achieve this capability. I know this is a general statement to this approach without details but is there an easier way... or maybe not so much easier, but a better way that adheres to the MVVM pattern a little better?
It's driving me crazy that the DataGrid control's Columns property can't be bound... seems like such a simple thing.
FYI - Before it's suggested to use AutoGenerateColumns = True, the class being bound for each item in the collection that's bound to DataGrid.ItemsSource does not have individual properties to identify what is bound to the columns... it's a collection property that contains the columns in order to keep them completely dynamic so that particular path is out. Also, handling the AutoGeneratingColumns and using e.Cancel to show/hide columns is also iffy for this same reason (I think).
I agree that it is a pain that DataGrid.Columns cannot be bound to. My recommendation here would be to define your columns in the ViewModel in an ObservableCollection. In the View (code behind), handle the CollectionChanged event of this ObservableCollection, and modify the DataGrid.Columns in code.
While this solution is less elegant, it is straightforward. For your ViewModel, you can unit test that the CollectionChanged event is raised properly when columns are added, removed or moved. The View code cannot be tested, so I guess this is something you need to live with. The advantage is that, if some day the DataGrid.Columns property can be databound, it will be easy to refactor this to remove the code behind.
Another way (I think) would be to create an attached behavior or a Blend behavior to take care of this. Attach it to the DataGrid; instead of binding to the DataGrid.Columns directly, bind to a property on the behavior, and have the behavior modify the DataGrid (the AssociatedObect) directly.
Does that make sense?
Cheers,
Laurent
I am deriving from combobox (WinForms) and am providing a new implementation for the Selectedvalue property.
It works fine as is, but any change to the selectedvalue property is not updating other controls bound to the same "binding context" to change their values accordingly.
I did try adding the BindableAttribute(true) to the property, but still it does nottrigger the change in value to the other linked controls.
The control's DataBindings.add(...) is all set up. And other controls are also bound to the same data filed on the same datasource.
Any ideas what i am doing wrong.
Have you called your base class' implementation of overridden methods? It's possible that failing to call the base class implementation is accidentally circumventing the code that fires various event plumbing.