Develop Reference

Nested datagrid column visibility based on the contents of its inner datagrid

I have a nested datagrid and I want to hide outer datagrid column when the inner datagrid doesn't have any data. I am using MVVM pattern. Model fills the data in the collections which is binded to the view.
Filled Datagrid
The list of Component1, 2 and 3 are displayed through a datagrid inside the outer datagrid. Each label family will have two collections left and right.
When the Model doesn't have any components for left label collection, then I want the Left column to be hidden completely. As in below image. Similarly for Right column.
Left Column Hidden
Please help me in achieving this.
I searched for similar situations on this site and google, but couldn't find anything similar to this.
Here is the XAML code:
<DataGrid ItemsSource="{Binding Labels}"
CanUserAddRows="False"
CanUserDeleteRows="False">
<DataGrid.Columns>
<DataGridTemplateColumn Width="10*" >
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding LabelFamily}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn Header="Right" Width="25*">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<DataGrid ItemsSource="{Binding LeftLabel.Components}"
CanUserAddRows="False"
CanUserDeleteRows="False">
</DataGrid>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn Header="Left" Width="25*">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<DataGrid ItemsSource="{Binding RightLabel.Components}"
CanUserAddRows="False"
CanUserDeleteRows="False">
</DataGrid>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
I am not posting the model code to keep the post short as much as possible.

You can create converter like this (I used ObservableCollection for testing, you should use your container):
public class NoElementVisibilityConverter : MarkupExtension, IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value == null)
return Visibility.Collapsed;
ObservableCollection<int> ienum = value as ObservableCollection<int>;
return ienum == null || ienum.Count() == 0 ? Visibility.Collapsed : Visibility.Visible;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
if (_converter == null)
_converter = new NoElementVisibilityConverter();
return _converter;
}
private static NoElementVisibilityConverter _converter = null;
}
And use it on your column like this:
<DataGridTemplateColumn Header="Left" Width="25*"
Visibility={Binding RightLabel.Components, Converter={local:NoElementVisibilityConverter}>
Don't forget to include Converter namespace in your Window.

Convert string to int using IValueConverter

How do I convert string values to integers and back using IValueConverter?
I have a database that consists of two tables; table CompanyX and table DeptY.
Table CompanyX has field ID(int), firstName, lastName, Email, Phone.
Table DeptY has field pID(int), Roles.
DeptY pID is foreign key To CompanyX ID. Every time I select someone in the Combobox, I want it to display as their ID in a DataGrid.
This is my ItemTemplate below:
<Application.Resources>
<DataTemplate x:Key="myTemplate">
<WrapPanel HorizontalAlignment="Stretch">
<TextBlock Text="{Binding FirstName}"/>
<Label />
<TextBlock Text="{Binding LastName}"/>
</WrapPanel>
</DataTemplate>
</Application.Resources>
This is my Combobox which is bound to the ItemTemplate:
<ComboBox Height="23" HorizontalAlignment="Right" Margin="0,90,267,0"
Name="comboID" ItemsSource="{Binding}" VerticalAlignment="Top"
Width="208" ItemTemplate="{StaticResource myTemplate}" />
And a DataGrid which displays:
<DataGridTemplateColumn x:Name="pIDColumn" Header="Person ID" Width="auto">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=pID, Converter= {StaticResource myConverter}}"/>
<DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTemplateColumn x:Name="rolesColumn" Header="Roles" Width="auto" >
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Path=Roles}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
IValueConverter which is not converting!!
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
string a = (string)value;
int b;
int.TryParse(a, out b);
return b;
}
public object ConvertBack(object value, Type targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}

You are converting the wrong way around. Convert() takes the binding source as input (int in your case), and outputs what the xaml is expecting (string).
But you don't even need a converter. You can bind straight to an int and WPF will automatically call ToString() on it to display it as text.

Like was said in the other answer, you are doing it backwards. The Convert side of an IValueConverter is meant for converting from the source property to what is in the bound element, in your case a textbox. You need to do your parsing on the ConvertBack side because that is what takes what is in the textbox (a string) and converts it back to a number.
public class IntToString : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return value.ToString();
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
int ret = 0;
return int.TryParse((string)value, out ret) ? ret : 0;
}
}

Winrt IValueConverter on a GridView item

I have a ObservableCollection<TimeSpan> Laps which I am databinding to a gridview. This works as expected but I need to apply a converter to set the format of the TimeSpan:
In my resources:
<utils:TimeToStringConverter x:Key="myConverter"/>
My Gridview:
<GridView HorizontalAlignment="Left" Height="278" Margin="78,220,0,0" VerticalAlignment="Top" Width="1278" ItemsSource="{Binding model.Laps}" />
I have the following converter which I want to apply on the items of a GridView / ListView in Winrt:
public class TimeToStringConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, string language)
{
TimeSpan t = (TimeSpan) value;
return t.ToString(#"hh\:dd\:ss\.fff");
}
public object ConvertBack(object value, Type targetType, object parameter, string language)
{
throw new NotImplementedException();
}
}
I can't figure out how to get the converter to work, and when I apply it on the GridView then it is looking for me to convert an Observable collection rather than just a TimeSpan item. What should I do here ?
Regards

You need something like a
<GridView
...>
<GridView.ItemTemplate>
<DataTemplate>
<TextBlock
Text="{Binding Converter={StaticResource myConverter}}" />
</DataTemplate>
</GridView.ItemTemplate>

Use the below modified line
I've just modified the item source like below
ItemsSource="{Binding model.Laps,Converter={StaticResource myConverter}}"
<GridView HorizontalAlignment="Left" Height="278" Margin="78,220,0,0" VerticalAlignment="Top" Width="1278" ItemsSource="{Binding model.Laps,Converter={StaticResource myConverter}}" />

Binding DataGrid's FontWeight property to value converter

I'm trying to make cell bold or normal if item new/old inside DataGrid but stumbled upon erro..
Looks like my issue described here: Why can I not bind the Visiblity of a DataGridTemplateColumn in Silverlight 4?
I'm getting following error:
Object of type 'System.Windows.Data.Binding' cannot be converted to
type 'System.Windows.FontWeight'.
And my XAML looks like so:
<sdk:DataGridTextColumn Header="Subject" Binding="{Binding Subject}" CanUserReorder="True" CanUserResize="True" CanUserSort="True" Width="Auto" FontWeight="{Binding IsNew, Converter={StaticResource BoolToFontWeightConverter}}" />
My question is there any workaround to get this working? I'm not even using template column, it's plain text column..
public class BoolToFontWeightConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
return ((bool)value) ? FontWeights.Bold : FontWeights.Normal;
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return (FontWeight)value == FontWeights.Bold;
}
}

The FontWeight property of the DataGridTextColumn is not a dependency property and thus will not support bindings. A workaround would be to use a DataGridTemplateColumn with a TextBox as the DataTemplate and set the appropriate bindings there, something like:
<sdk:DataGridTemplateColumn Header="Subject"
CanUserReorder="True"
CanUserResize="True"
CanUserSort="True"
Width="Auto">
<sdk:DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding Subject}" FontWeight="{Binding IsNew, Converter={StaticResource BoolToFontWeightConverter}}"/>
</DataTemplate>
</sdk:DataGridTemplateColumn.CellTemplate>
</sdk:DataGridTemplateColumn>

Define DataGrid's rows declaratively in XAML

I have this code and I need to bind second and third cells in rows to different properties. Sorry for my bad english.
<DataGrid AutoGenerateColumns="False" HorizontalAlignment="Stretch" Name="measureDataGrid" VerticalAlignment="Stretch">
<DataGrid.Columns>
<DataGridTextColumn x:Name="measureName" Header="Наименование" Width="*" />
<DataGridTextColumn x:Name="measureValue" Header="Значение" Width="Auto" />
<DataGridTextColumn x:Name="measureDestValue" Header="Потенциальное значение" Width="Auto" />
</DataGrid.Columns>
<DataGrid.Items>
<!--<DataGridRow>-->
<RowDefinition/>
<RowDefinition/>
<RowDefinition/>
</DataGrid.Items>
</DataGrid>

So if you need to convert a value (this can be used to show different values in the same column for different rows) you can use a ValueConverter.
Create a class that implements IValueConverter That would look something like this:
public object Convert(object value, Type targetType, object parameter,System.Globalization.CultureInfo culture)
{
bool boolValue = (bool)value;
if(boolValue)
return x;
else
return y;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
Create a reference to it in your xaml:
<converters: MeasureConverter x:Key="MeasureConverter" />
And use in your DataGridTextColumn like this:
<DataGridTextColumn Header="measureRow1" DataMemberBinding="{Binding ValueThatWouldDetermineWhatToShow, Converter={StaticResource MeasureConverter}}" />
<DataGridTextColumn Header="measureRow2" DataMemberBinding="{Binding ValueThatWouldDetermineWhatToShow, Converter={StaticResource MeasureConverter}}" />