I have my data grid "dgSubsytem" column defined like below
<my:DataGridComboBoxColumn x:Name="cmbSubSysSupplier_SRV" Header="Supplier" Width="160"
ItemsSource="{Binding RelativeSource}" SelectedValueBinding="{Binding SupplierId}" />
As you see from the code i am having a combo box inside a grid .
Item source of this combo box is a datatable which is bound to it in the code behind .
Item source of the grid also another datatable bound in code behind .
code of binding item source of combobox in code behind is as follows
cmbSubSysSupplier_SRV.ItemsSource = dsComboBox.Tables[3].DefaultView;
cmbSubSysSupplier_SRV.DisplayMemberPath="FullName" ;
cmbSubSysSupplier_SRV.SelectedValuePath = "SupplierId";
Problem is combo box itself not rendering . But I can see the value of the Supplier rendered as text . What is the problem?
There are 2 parts here:
List of values to be populated in ComboBox: ItemsSource, should be bound using a StaticResource, with a List<X> fields exposed from your ViewModel.
The actual value (here X) should be bound to SelectedItemBinding using binding to data item.
No binding in code behind required.
At what point does your code-behind stuff run?
You're setting the ItemsSource in two places - in the XAML and in the Code-Behind. Whichever one runs second will overwrite the value of the first one, so only the last value set will be used.
I suspect your XAML is getting run last, and RelativeSource is probably not a property on your DataContext, so your ComboBox ends up being bound to nothing.
To fix it, simply remove your ItemsSource binding in the XAML for the DataGridComboBoxColumn
<my:DataGridComboBoxColumn x:Name="cmbSubSysSupplier_SRV"
Header="Supplier" Width="160"
SelectedValueBinding="{Binding SupplierId}" />
In addition, the DefaultView of a DataTable will return an object of type DataView, and DataView does not have properties called FullName or SupplierId, so your SelectedValuePath and DisplayMemberPath properties won't work.
I'd recommend building a list of KeyValuePair<int,string> out of your data items, and bind your ComboBoxColumn.ItemsSource to that list, then switch the SelectedValuePath to "Key" and the DisplayMemberPath to "Value"
I personally fought with DataGridComboBoxColumn for long time and i think the way is to use DataGridTemplateColumn. Here is an exemple :
Looks a lot of code but evective.
Put the collection as resource :
<Grid.Resources>
<CollectionViewSource x:Key="StructuresCollection" Source="{Binding StructuresList, Mode=OneTime}"/>
</Grid.Resources>
<DataGridTemplateColumn Header="Structure" >
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Structures.Name}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate >
<DataTemplate>
<ComboBox x:Name="CStructures" SelectedItem="{Binding Structures}" DisplayMemberPath="Name" SelectedValue="{Binding IDStructure, UpdateSourceTrigger=PropertyChanged}" SelectedValuePath="{Binding IDStructure}" ItemsSource="{Binding Source={StaticResource StructuresCollection}}" />
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
Related
I have a datagrid where the ItemsSource is set in code-behind for example:
var grid = grdEmploy as DataGrid;
grid.ItemsSource = employments; // list of objects
In this grid, I have several drop downs being used when editing the row. The options are currently held in a local CollectionViewSource, for example:
<CollectionViewSource x:Key="StatusList" CollectionViewType="ListCollectionView"/>
And set when the window is loaded like so:
var statusList= Functions.GetStatuses(); // returns a List<>
CollectionViewSource itemCollectionViewSource;
itemCollectionViewSource = (CollectionViewSource)(FindResource("StatusList"));
itemCollectionViewSource.Source = statusList;
Then the binding of the column for the grid would look like so:
<DataGridTemplateColumn Header="Employment Status" HeaderStyle="{StaticResource WrappedColumnHeaderStyle}">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock>
<TextBlock.Text>
<MultiBinding>
<MultiBinding.Converter>
<local:AimTypeConverter />
</MultiBinding.Converter>
<Binding Path="EmpStat" />
<Binding Path="SourceCollection" Source="{StaticResource StatusList}" />
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox SelectedValue="{Binding EmpStat}" SelectedValuePath="Value" DisplayMemberPath="Text" ItemsSource="{Binding Source={StaticResource StatusList}}"></ComboBox>
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>
This all works great however I have hit a snag whereby one of the columns needs to show different options based on another column. For example if Column A is "1" show Options 2,3, if "2", show Options 3,4 etc.
My thoughts were to load all options into the local list and somehow filter them but I'm not sure how best to do this, any help on this would be appreciated.
The way to solve this using the MVVM pattern would be to define a collection property in the Employee class, or whatever you call it, and then return an already filtered collection from this property based on the value of the property bound to "Column A".
I am afraid it doesn't make much sense to define a single source collection in the code-behind if you want to bind to several source collections, filtered or not, in the DataGrid. I would recommend you to put your filtering logic in the view model.
If I have a combo box by iteself with an item source e.g.:
<ComboBox ItemsSource="{Binding Combobox.Options}"/>
This works fine. Where Combobox.Options is a list of strings {"option1","option 2",... etc}
However, I want to have a combobox within a datagrid which has an item source:
e.g.:
<DataGrid CanUserAddRows="False" AutoGenerateColumns="False" SelectionMode="Single" ItemsSource="{Binding Users.Table.Tables[0]}">
But I keep getting an empty combo box when I add it into a datagrid template column. I have also tried the Find Ancestor Relative soure but also got an empty combo box.
Finally managed to find the problem. Needed to add a DataContext when getting the list for the item source within the datagrid:
<ComboBox ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}"/>
I have a datagrid of rows which contain data read from a web server and values I want to write into a webserver. I write the values in getting the user to input a number into the appropriate column and click an adjacent text box;
<DataGrid x:Name="datagridDERControl" HorizontalAlignment="Center" VerticalAlignment="Center" Background="#FF322D2D" Height="382" Margin="10,78,10,10" Width="972" ItemsSource="{Binding Path=NFDataSource, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<DataGrid.Columns>
<DataGridTemplateColumn Width="100" Header="Write Set Point">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBox Width="100" Text="{Binding Path=WriteSetPoint, Mode=OneWayToSource, UpdateSourceTrigger=PropertyChanged}"></TextBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn Width="100" Header="Global Trip">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Button Name="buttonGlobalTrip" Width="100" Click="buttonGlobalTrip_Click"></Button>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid
How do I extract the specific textbox string per row to use in my view model.
It's always difficult to answer a question where the relevant details have been omitted by the question author. However, I shall try!
You have data bound (presumably) a collection property named NFDataSource to your DataGrid.ItemsSource property. That is the collection that represents the data in your DataGrid, so to 'extract' a specific value, you need to look into your data items in your collection.
One handy property in the DataGrid class is the SelectedItem property. this enables you to data bind an object (of the same type as those in your NFDataSource collection) to this property, which accesses the data object behind the row that is currently selected in the UI:
<DataGrid ItemsSource="{Binding NFDataSource}" SelectedItem="{Binding SelectedItem}" />
Now you can utilise your SelectedItem property to access the values from the selected row in the DataGrid:
string someValue = SelectedItem.SomeProperty;
As you tagged this with MVVM and databinding, I'll assume you're using these and have just got muddled.
"I have a datagrid of rows which contain data read from a web server
and values I want to write into a webserver."
So your viewmodel has a property, which is a collection of a custom class, that represents data fetched from a webservers.
"I write the values in getting the user to input a number into the
appropriate column and click an adjacent text box"
So this VM property is two-way bound to a datagrid, so that each item in the collection represents 'one row', and the properties on those items represent your 'columns'. The user can make changes to the UI displayed values, and because of the two way databinding the VM property is also updated.
"How do I extract the specific textbox string per row to use in my
view model."
Why do you need the specific textbox string, if it is databound to a property (or rather to a property on a class contained in a collection) in your VM anyway? If you've set up your VM this way, and are using databinding, you rarely need to worry about UI specific things such as which row in a datagrid is clicked.
As Sheridan points out though, you can also bind to properties on the datagrid such as SelectedItem so that you can perform additional operations beyond just reading/writing data. SelectedItem for your datagrid will be of the type that populates your VM collection, so will have the appropriate properties.
For example, if your VM collection is an IQueryable<Person> and that is bound to the ItemsSource of the datagrid then the SelectedItem will be of type Person. You could then have a VM property called SelectedPerson which is bound to that SelectedItem, and access things like SelectedPerson.Name etc.
i am trying to set selected item through following code but its not working:
<StackPanel Orientation="Horizontal">
<TextBlock Text="Sort by" Margin="10" VerticalAlignment="Center"/>
<ComboBox Width="{StaticResource ComboWidth}" x:Name="sortcombo" ItemsSource="{Binding Path=SortOrder}" SelectionChanged="SearchCombo_SelectionChanged" SelectedItem="{Binding Path=DefaultSortIndex}">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Sort}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
</StackPanel>
however it works fine if i use selectedIndex instead with binding to 0th index. Any thing wrong with declaration?
By the name of your property DefaultSortIndex maybe you are trying to bind an int for SelectedItem.
SeletedItem refers to an element of your collection binded to ItemsSource, so the property binded to SelectedItem must be of type of your collection elements.
If you bind int value to selected item then it will not work, you should bind element for that. For int value you can set it as mentioned in following post :
Set Selected Item of WPF Combobox to User Setting
found out the issue, actually the data source was creating new list everytime I call getData().
Hi I have to create a wpf grid which is having combo box in it . I have to bind grid to a data table dtGrid and combobox item source to a datatable dtcmb . I wrote template below for embedding combo box in grid .
Now I need to access the combo in code behind to specify item source and DisplayMemberPath, ,SelectedValuePath,SelectedValue,
Even though i could access data grid in code behind I could not access combo box . what is the prob ?
<my:DataGridTemplateColumn x:Name="supplierName" Header="Supplier" Width="60" >
<my:DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox x:Name="cmbSubSysSupplier_SRV" IsTextSearchEnabled="True"
Height="23" ItemsSource="{Binding}" Width="80" />
</DataTemplate>
</my:DataGridTemplateColumn.CellTemplate>
</my:DataGridTemplateColumn>
You should use a DataGridComboBoxColumn for this particular case. You can access it in code behind through its x:Name property. The DataGridComboBoxColumn object will give you access to all the properties you need.