DataGrid Column Header text change from ViewModel

Question

Hi,

I need to change the column header text of the datagrid. I have defined a viewmodel and exposed a property, but I am not sure how I can bind the column header to this property.

I am trying to follow MVVM patern and using prism. I am very new to this and I am almost getting lost.

How can I resolve this problem

I am using Silverlight4 and VS2010

Thanks

ab

Answer 1

I am not sure if you can, the last I looked at binding Headers was in SL 3 but back then it was not a FrameworkElement so you could not bind to it. Not sure if it changed since then.

Can you post your xaml for the grid and your viewmodel bind property? 

Answer 2

What I am trying to do is very similar to an Email Client. When you click on th Inbox folder I need to show the Header for the recipient as "From" when in Send folder change the Header for the recipient as "To" If I can change this, I can use the same view for all the folders clicked, thats the plan. xaml

       <UserControl.Resources>
		<DataTemplate x:Key="CheckboxGrid">
			<Grid>
				<CheckBox IsThreeState="False" 	IsChecked="False"/>
			</Grid>			
		</DataTemplate>
	</UserControl.Resources>
    
    <Grid x:Name="LayoutRoot" Background="Aqua" HorizontalAlignment="Stretch" Margin="2,0" >

        <sdk:DataGrid ItemsSource="{Binding GetMessages}" AutoGenerateColumns="False" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch">
    		<sdk:DataGrid.Columns >
    			<sdk:DataGridTemplateColumn CellTemplate="{StaticResource CheckboxGrid}" Width="SizeToCells"/>
                <sdk:DataGridTextColumn x:Name="ColParicipant" Binding="{Binding ParticipantName}" Header="From" IsReadOnly="True" Width="1*"/>
				<sdk:DataGridTextColumn x:Name="ColFacility" Binding="{Binding FacilityName}" Header="Facility"  IsReadOnly="True" Width="1*"/>
				<sdk:DataGridTextColumn x:Name="ColPatient" Binding="{Binding PatientName}" Header="Patient Name"  IsReadOnly="True" Width="1*"/>
				<sdk:DataGridTextColumn x:Name="ColSubject" Binding="{Binding Subject}" Header="Subject"  IsReadOnly="True" Width="1*"/>
				<sdk:DataGridTextColumn x:Name="ColTime" Binding="{Binding Timestamp}" Header="Timestamp" IsReadOnly="True" Width="*"/>
    		</sdk:DataGrid.Columns>
		</sdk:DataGrid>
    </Grid>

public partial class MessageListView : UserControl
    {
        public MessageListView(MessageListVM viewModel)
        {
            InitializeComponent();

            this.Loaded += (s, e) =>
            {
                this.DataContext = viewModel;
            };
        }

    }

 

 

 

(ViewModel)

public class MessageListVM
    {
        public MessageListVM(IMessageService messageService)
        {
            this.messageService = messageService;
        }

        public IEnumerable<Message> GetMessages
        {
            get
            {
                return messageService.GetFolderMessages();
            }
        }

        public object GetHeader
        {
            get
            {
                return "From";
            }
        }
        private readonly IMessageService messageService;
    }

Answer 3

Have a look at this post, as you will see it is still not small task to achieve this.

 

http://forums.silverlight.net/forums/p/176929/398718.aspx 

Answer 4

thanks....

I could get this working by creating the ViewModel as a local resource, and by providing a empty constructor for the viewmodel.

But I also set the datacontext to the same viewmdoel during load event of the view.

Is it right to do this? Will it create 2 instance of the same viewmodel ? I can post the code for this if required.

Answer 5

A StaticResource declared ViewModel will create a new instance unless you use a ViewModel locator pattern. If you go this route maybe use your StaticResource ViewModel across your view and rather not set the DataContext on the load event.

http://johnpapa.net/silverlight/simple-viewmodel-locator-for-mvvm-the-patients-have-left-the-asylum/ 

Answer 6

Thanks

I found another article  ...

its not neat .. but will work for me...

Answer 7

Would you mind posting the link of that article here to share with other communites.

Answer 8

I dont remember the link to the article.

In case I get I can post it.

Right now I am pasting the code I have

<UserControl

x:Class="ccc.RI.SMViewDefault.View.DefaultListView"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk" 

xmlns:conv="clr-namespace:ccc.RI.Common.Converters;assembly=ccc.RI.Common"

mc:Ignorable="d"

d:DesignHeight="300" d:DesignWidth="400">

<UserControl.Resources>

<conv:BooleanFontConverter x:Key="boofont"></conv:BooleanFontConverter>

        <conv:BindingConverter x:Key="BindCon"/>

        <Style x:Key="ColBinding" TargetType="sdk:DataGridColumnHeader" >

            <Setter Property="ContentTemplate" >

                <Setter.Value>

                    <DataTemplate>

                        <ContentPresenter Content="{Binding Converter={StaticResource BindCon}}"  />

                    </DataTemplate>

                </Setter.Value>

            </Setter>

        </Style>

        

        <DataTemplate x:Key="ParticipantCol">

            <Grid>

                <TextBlock Text="{Binding ParticipantName}" FontWeight="{Binding IsRead,Converter={StaticResource boofont}}" Margin="0,4"

></TextBlock>

            </Grid>

        </DataTemplate>

        

</UserControl.Resources>

<Grid x:Name="LayoutRoot" HorizontalAlignment="Stretch" Margin="1,0,1,11">

        <TextBox Text="{Binding GetParticipantHeader}" x:Name="participantHeader" />

        

<Border BorderBrush="#FFA6B6D6" BorderThickness="2" CornerRadius="2"

x:Name="defaultview">

<sdk:DataGrid ItemsSource="{Binding Path=GetMessages}" 

 AutoGenerateColumns="False" 

                          ColumnHeaderStyle="{StaticResource ColBinding}"

 >

<sdk:DataGrid.Columns >

                    

                    

                    <sdk:DataGridTemplateColumn 

                        CellTemplate="{StaticResource ParticipantCol}" 

                        Header="{Binding Text, ElementName=participantHeader}"

                        Width="1*"  

                        SortMemberPath="ParticipantName"/>

                    

                    

</sdk:DataGrid.Columns>

</sdk:DataGrid>

</Border>

</Grid>

</UserControl>

Also u need a converter.

namespace ccc.RI.Common.Converters

{

    public class BindingConverter  : IValueConverter

    {

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            if (value.GetType().Name == "Binding")

            {

                ContentControl cc = new ContentControl();

                Binding newValue = value as Binding;

                newValue.Mode = BindingMode.TwoWay;

                cc.SetBinding(ContentControl.ContentProperty, newValue as Binding);

                return cc;

            }

            else

            {

                return value;

            }

        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            return null;

        }

    }

}

Hope this helps

I dont remember the link to the article.

In case I get I can post it.

Right now I am pasting the code I have

<UserControl

x:Class="ccc.RI.SMViewDefault.View.DefaultListView"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk" 

xmlns:conv="clr-namespace:ccc.RI.Common.Converters;assembly=ccc.RI.Common"

mc:Ignorable="d"

d:DesignHeight="300" d:DesignWidth="400">

<UserControl.Resources>

<conv:BooleanFontConverter x:Key="boofont"></conv:BooleanFontConverter>

        <conv:BindingConverter x:Key="BindCon"/>

        <Style x:Key="ColBinding" TargetType="sdk:DataGridColumnHeader" >

            <Setter Property="ContentTemplate" >

                <Setter.Value>

                    <DataTemplate>

                        <ContentPresenter Content="{Binding Converter={StaticResource BindCon}}"  />

                    </DataTemplate>

                </Setter.Value>

            </Setter>

        </Style>

        

        <DataTemplate x:Key="ParticipantCol">

            <Grid>

                <TextBlock Text="{Binding ParticipantName}" FontWeight="{Binding IsRead,Converter={StaticResource boofont}}" Margin="0,4"

></TextBlock>

            </Grid>

        </DataTemplate>

        

</UserControl.Resources>

<Grid x:Name="LayoutRoot" HorizontalAlignment="Stretch" Margin="1,0,1,11">

        <TextBox Text="{Binding GetParticipantHeader}" x:Name="participantHeader" />

        

<Border BorderBrush="#FFA6B6D6" BorderThickness="2" CornerRadius="2"

x:Name="defaultview">

<sdk:DataGrid ItemsSource="{Binding Path=GetMessages}" 

 AutoGenerateColumns="False" 

                          ColumnHeaderStyle="{StaticResource ColBinding}"

 >

<sdk:DataGrid.Columns >

                    

                    

                    <sdk:DataGridTemplateColumn 

                        CellTemplate="{StaticResource ParticipantCol}" 

                        Header="{Binding Text, ElementName=participantHeader}"

                        Width="1*"  

                        SortMemberPath="ParticipantName"/>

                    

                    

</sdk:DataGrid.Columns>

</sdk:DataGrid>

</Border>

</Grid>

</UserControl>

Also u need a converter.

namespace ccc.RI.Common.Converters

{

    public class BindingConverter  : IValueConverter

    {

        public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            if (value.GetType().Name == "Binding")

            {

                ContentControl cc = new ContentControl();

                Binding newValue = value as Binding;

                newValue.Mode = BindingMode.TwoWay;

                cc.SetBinding(ContentControl.ContentProperty, newValue as Binding);

                return cc;

            }

            else

            {

                return value;

            }

        }

        public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)

        {

            return null;

        }

    }

}

Hope this helps