If I have a DataSet as a result of a SQL query, can I bind it directly to a TreeView and show the hierarchy of my data? I know I'd have to use several HierarchicalDataTemplates, but I don't know how to tell each one what data to display.
If I have a 4-level hierarchy, like so:
<HierarchicalDataTemplate x:Key="FirstLevelTemplate" ItemTemplate="{StaticResource SecondLevelTemplate}"/>
<HierarchicalDataTemplate x:Key="SecondLevelTemplate" ItemTemplate="{StaticResource ThirdLevelTemplate}"/>
<HierarchicalDataTemplate x:Key="ThirdLevelTemplate" ItemTemplate="{StaticResource FourthLevelTemplate}"/>
<DataTemplate x:Key="FourthLevelTemplate"/>
What property(ies) need to be set to display my data directly from a DataSet?
edit: Ideally, I'd like to do this using a single self-referencing DataTable.
I do not think you can do that.
The Treeview control, and the HierarchicalDataTemplate expect a hierarchy of objects. The DataSet is inherently flat.
You will have to somehow convert that dataset to a hierarchy of objects, each with its own "Children" collection. The ItemsSource of the treeview will be bound to the "top level collection" (the rows without a parent reference).
Each HierarchicalDataTemplate will have its ItemsSource property bound to the corresponding Children property.
There might be a solution using converters, but if it exists it would probably end up being more complicated than straight up reshaping the data before binding.
This site has some very good examples of using treeview.
BeaStollnitz
First, you would set the ItemsSource of the TreeView to the DataSet.
Next you would set the ItemTemplate of the TreeView to the FirstLevelTemplate.
ItemTemplate="{StaticResource FirstLevelTemplate}"
The first template must reference the items that will use the second level template. Add an items source to this hierarchical template like so:
<HierarchicalDataTemplate x:Key="FirstLevelTemplate" ItemsSource="{Binding ChildItems}" ItemTemplate="{StaticResource SecondLevelTemplate}"/>
Change "ChildItems" to refer to the property within your DataSet that contains the child items. Repeat this for each HierarchicalDataTemplate.
Finally, you need to add controls to your DataTemplates in order to display the data. Here's a simple example:
<DataTemplate x:Key="FourthLevelTemplate"/>
<Border BorderThickness="1" BorderBrush="Gray" CornerRadius="3">
<TextBlock Text="{Binding DataProperty}"
HorizontalAlignment="Center" VerticalAlignment="Center"/>
</Border>
</DataTemplate>
In this case, you would replace "DataProperty" with the property name of your data field. Note that you could add other controls (like TextBox, ComboBox, etc) to display additional data.
Related
I'm building a window with a set of rows that share the same layout, but their contents should be different, eg:
| (Label Content:)"Name1" | (Textbox Text)"SomeText" |
| (Label Content:)"Name5" | (Textbox Text)"OtherText" |
I've defined a DataTemplate which basically holds a Grid specifying the size of each column, holds all the elements it requires (a few labels, textboxes, etc.) and sets their common properties.
<UserControl.Resources>
<DataTemplate x:Key="AxisRangeEntry" x:Shared="False">
<Grid HorizontalAlignment="Stretch" VerticalAlignment="Top">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="50" />
<ColumnDefinition Width="50" />
....
</Grid.ColumnDefinitions>
<Label x:Name="MyLabel" Grid.Column="0" HorizontalAlignment="Left" VerticalAlignment="Center">
...
<TextBox x:Name="MyTextbox" Grid.Column="2" Width="110" HorizontalContentAlignment="Right" />
...
</Grid>
</DataTemplate>
</UserControl.Resources>
Then in my window I start adding the data template as ContentControls in a stack panel:
<ContentControl ContentTemplate="{StaticResource AxisRangeEntry}" />
<ContentControl ContentTemplate="{StaticResource AxisRangeEntry}" />
....
I'm struggling to figure out how I can define certain properties of controls inside the DataTemplate to be bindable to, and bind them to a static value/external property when I start defining the ContentControls. Effectively each ContentControl would need to be able to define things like it's MyLabel content and MyTextbox text.
I've previously created CustomControls, which had DependencyProperties on them, which I could then bind to when adding them on another window. With a DataTemplate however I'm not sure how I would define these fields as bindable and bind to them when including a new version of the template.
Any help would be appreciated.
From what it sounds like, you are not using the MVVM pattern.
For your situation, I'd recommend using MVVM -- take a look at this article for a quick intro for something that would fit your case (ItemsControl with an ItemTemplate)
What you would do is create an ObservableObject to represent each row, and then bind the collection of ObservableObjects to an ItemsControl's ItemsSource, with the ItemTemplate set to the DataTemplate you created. In the DataTemplate, you would specify each binding to the property on the ObservableObject's row, and WPF would bind to the correct instance for each row.
http://www.wpf-tutorial.com/list-controls/itemscontrol/
Either way, DataTemplates are primarily used for templating a certain data-type. If you really need to implement the view in this way, a custom UserControl with dependency properties would be the way to go.
You present a dynamic nature of items to be bound, so this answer will attempt to provide guidance within the parameter's set.
...[to] define certain properties of
controls inside the DataTemplate to be bindable to,
Within a template the binding will default to the parents data context. Simply saying {Binding} will default to that item in the data context. If the bound item has a specific property then use {Binding MyPropertyName}. Just verify that the parent, or its ancestors have a valid data context.
Think of data templates in its final location, as if you had hard coded it there. It will behave the same....
and bind them to a static value/external property when I start defining the
ContentControls.
Since this sounds like it is in a custom control, the datacontext will be the ultimate consumer's datacontext and most likely the datacontext will be worthless.
If it is on a custom control, then use named binding and bind it to a property on the control. For example the control's name, in XAML, is given the name "MyControl" (x:Name="MyControl")and in the template binding, one can path directly to it such as
{Binding MyCustomControlDependencyProperty, ElementName=MyControl}
created CustomControls, which had Dependency properties
With the above rules one can still, and should IMHO, use dependency properties of the custom control to pass on the information from the consumer to the the datatemplate which will use it dynamically..
<StackPanel DataContext="{StaticResource Employees1}">
<ListBox ItemsSource="{Binding}" DisplayMemberPath="Name"
IsSynchronizedWithCurrentItem="True"/>
<Label Content="{Binding Path=Count}"/>
<Label Content="{Binding Path=Name}"/>
</StackPanel>
How does the binding for the labels get resolved? How is it decided that the content of the second label is bound to Employees1.Count (and not to Employee.Count), while the first label is bound to
Employee.Name and synchonized with the listbox selection? Also, what if I would like to bind the first label to Employee.Count instead?
(Employee has properties Name (and possibly Count), Employees1 is an ObservableCollection of type Employee).
EDIT: So, the question here is WHY the first label displays the number of employees in the ObservableCollection, while the second label displays the name of a specific employee in the collection, the one that is currently selected in the ListBox. Apparently, the first label binds to the entire collection, and the second label to a specific employee in the collection. But why, and how to control this behavior.
From MSDN Data Binding Overview, Binding To Collections, section "Current Item Pointer":
Because WPF binds to a collection only by using a view (either a view
you specify, or the collection's default view), all bindings to
collections have a current item pointer.
and section "Master-Detail Binding Scenario":
This works because when a singleton object (the ContentControl in this
case) is bound to a collection view, it automatically binds to the
CurrentItem of the view.
In your example, the second Label automatically binds to the current item of the default view of the Employees1 collection. The first Label would also bind like this, but since the item object does not have a Count property it apparently falls back to a binding to the Count property of the collection itself. However i don't know if the latter behaviour is documented somewhere.
As Blam says - the labels have no relationship to the listbox - I think what you're trying to do here is bind an observableCollection of Employees with properties Count and Name to the listbox..
To do this you'll need an ItemsTemplate in the listbox
<ListBox ItemSource={Binding Employees1}>
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Label Content="{Binding Count}" />
<Label Content="{Binding Name}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Let me try and answer the questions.
An ObservableCollection has a property Count.
As for getting a single property on the second label it is making some assumptions.
You might not get the same behavior in other version of .NET.
Should not bind a control that displays a single value to a collection.
If you want the selected item from the ListBox see this link
enter link description here
Any help on this really appreciated. In summary I'm trying to databind to properties of a custom class instantiated in xaml that then forms the content of a templated listboxitem (phew!).
I have a simple c# class called MenuItem. It has two properties:
- Heading
- Icon
Concentrating on just one of those menu items (i.e. to provide a simple example of where I am stuck) If I do this (with the values hard coded) it works fine:
<ListBox>
<ListBoxItem ContentTemplate="{StaticResource MenuItemTemplate}">
<myclasses:MenuItem Heading="News" IconImage="News.png"/>
</ListBoxItem>
</Listbox>
Where MenuItemTemplate is an appropriate DataTemplate in the resources section binding each property) containing lines such as:
<TextBlock x:Name="tbHeading" Text="{Binding Heading}">
Wheareas when I try to use binding to set the Heading property it falls over (AG_E_PARSER_BAD_PROPERTY_VALUE error)- e.g.:
<ListBox>
<ListBoxItem ContentTemplate="{StaticResource MenuItemTemplate}">
<myclasses:MenuItem Heading="{Binding NewsHeading, Mode=OneWay}" Icon="News.png"/>
</ListBoxItem>
<Listbox>
I've wondered if it is because I'm doing some kind of double binding (i.e. the template is binding to a value on the MenuItem class that needs to be bound) and that's not possible? I've tried having the properties declared as dependency properties but no difference (although I only learned about those today so I may be missing something).
I know I could set the menuitem objects up in the view model, and bind from there, but I would like to understand why the above doesn't work (as for my purposes there are advantages in constructing the menu items in the xaml).
Thank you!!!!
Ian
thanks for sticking with this. I agree the listbox might not be needed - but even if I reduce it to just one item in a contentcontrol:
<ContentControl ContentTemplate="{StaticResource MenuItemTemplate}">
<myclasses:MenuItem Heading="{Binding NewsHeading, Mode=OneWay}" IconImage="News.png"/>
</ContentControl>
I still have the same problem - which is that I can get databinding to work within the content of a contentcontrol (prior to it being presented by the datatemplate referred to in ContentTemplate) using purely xaml.
I.e. the above bit of xaml doesn't work - it throws an error on the bit that binds the NewsHeading:
Heading="{Binding NewsHeading, Mode=OneWay}
So I am trying to understand whether what I'm doing is impossible, or whether it is but I'm doing it wrong.
Thanks.
Assuming that you have multiple MenuItem classes (because you're putting them in a listbox and ti wouldn't make sense to do that if you just had one). You need to bind the collection to the ItemsSource property of the ListBox.
Somehting like this:
<ListBox ItemsSource="{Binding MyMenuItems}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Heading}"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Note that the above assumes you've set the DataContext on the page to an object with a property called MyMenuItems which is a collection of your MenuItem objects.
To see a full example of this, look at the default code created when you create a new "Windows Phone Databound Application".
Edit:
Based on your comments, it seems that a ListBox is not the most appropriate solution to your needs. A ListBox is designed/intended to take a collection of items and display them in a list.
If you have a number of different objects which you know about at design time and simply wish to have them one on top of another (giving the appearance of a list) you could simply put them inside a ScrollViewer and/or a StackPanel (or other appropriate container). Plus, you would still be able to databind if you did it this way.
Is it possible to group items in a ItemsControl or Listbox in Silverlight? These controls are bound to a DomainDataSource.
Or are there any 3rd party controls that do this?
UPDATE:
This is the sort of UI I am trying to create.
You can do this by using nested ItemsControls bound to a PagedCollectionView.
Say I have a datasource - MyItems - with fields: Category, Section and Option. I can create a PagedCollectionView from an IEnumerable(of MyItems) and tell it which fields to group by.
Dim original As IEnumerable(Of MyItems) = GetMyItems()
Dim pcv = New PagedCollectionView(original)
pcv.GroupDescriptions.Add(New PropertyGroupDescription("Category"))
pcv.GroupDescriptions.Add(New PropertyGroupDescription("Section"))
Then I bind my first ItemsControl to the PagedCollectionView
hisMyItems.ItemsSource = pcv.Groups
The PCV creates a nested hierachy like:
-Name
-Items
where Name is the value in the grouped field and Items contains the rows/objects in that grouping. I guess you could also create the PCV in xaml if you prefer.
The xaml would look something like:
<controls:HeaderedItemsControl x:Name="hisMyItems" Header="{Binding Name}" ItemsSource="{Binding Items}" >
<controls:HeaderedItemsControl.ItemTemplate>
<DataTemplate>
<controls:HeaderedItemsControl Header="{Binding Name}" ItemsSource="{Binding Items}" ItemsPanel="{StaticResource ItemsPanelTemplate1}" >
<controls:HeaderedItemsControl.ItemTemplate>
<DataTemplate>
<Button Content="{Binding Option}" />
</DataTemplate>
</controls:HeaderedItemsControl.ItemTemplate>
</controls:HeaderedItemsControl>
</DataTemplate>
</controls:HeaderedItemsControl.ItemTemplate>
</controls:HeaderedItemsControl>
I hope that makes sense. I have tried to simplify things from my actual app but I could have made some mistakes in copying it over. Obviously you could use normal ItemsControls or other controls too and customize with templates etc.
The DataGrid control supports grouping.
Tim Heuer has a good blog on grouping with a datagrid.
link text
Perhaps the control you are really looking for is the Accordian Control from the Toolkit.
See sample of Accordian behaviour here.
Note that the actual appearance is as style-able as any other control. The basic function is to group categories of items that would otherwise be a straight-forward List.
I've got a WPF tab control that contain several duplicate controls as Tab Page content
<TabControl ItemsSource="{Binding}" Name="tabControl">
<TabControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}"/>
</DataTemplate>
</TabControl.ItemTemplate>
<TabControl.ContentTemplate>
<DataTemplate>
<local:InnerDataEntryControl DataContext="{Binding Data}"/>
</DataTemplate>
</TabControl.ContentTemplate>
</TabControl>
On the InnerDataEntry control there is a list box. I've got a command on the outer form that requires the selected items from the list box on the control. I can't figure out how to access the list box on the tab control itself. When I try to query the selected items, I get the bound items and not the list box itself.
I don't want to pollute the business layer with an 'IsSelected' property on my list items, and I suppose I could create a view model if necessary, but it just seems wrong that I can't get information about the actual content control of a tab page.
I hope that I'm just missing something obvious.
This was asked earlier in my WPF experience. To close the loop on the question, I'm going to post a link to the MSDN Magazine entry on the subject of MVVM.
Ultimately, the solution involves the creation of a view model that has the necessary properties bound to the parts of the tab control such that the view model doesn't need access in the way that I'm describing. Instead, the view model acts directly on the data that that is bound without having to reference the view directly.