One of my colleagues mentioned the “missing feature” of silverlight datagrid where in a message needs to be displayed when no records are present in the datagrid Itemsource.
So the objective is to make a datagrid which have a Empty Data grid template which may be overridden in case there are no records in the datagrid Item source. Like below.
The datagrid itself is trivial. I have introduced 3 dependency properties and overridden the Datagrid and the DataTemplate itself.
Here is how the XAML looks like
1: <local:DataGridWithEmptyTemplate ItemsSource="{Binding Person}" x:Name="MyDataGrid" AutoGenerateColumns="True">
2: <local:DataGridWithEmptyTemplate.EmptyTemplate>3: <local:EmptyDataTemplate Width="420.0" EmptyHeaderText="FirstName | LastName | Gender " >
4: <Border CornerRadius="5" BorderThickness="2" BorderBrush="Gray" Margin="5" >
5: <Border.Background>6: <LinearGradientBrush EndPoint="0.512,1.154" StartPoint="0.512,0.154">
7: <GradientStop Color="Red" Offset="1"/>
8: <GradientStop Color="AntiqueWhite" Offset="0.339"/>
9: </LinearGradientBrush> 10: </Border.Background>11: <StackPanel Width="Auto" Background="Transparent">
12: <TextBlock Text="No Records" ></TextBlock>
13: <TextBlock Text="Please change the criteria. This template may be changed using XAML!!"></TextBlock>
14: </StackPanel> 15: </Border> 16: </local:EmptyDataTemplate> 17: </local:DataGridWithEmptyTemplate.EmptyTemplate> 18: </local:DataGridWithEmptyTemplate>you may notice the Width and EmptyHeaderText Properties of EmptyDataTemplate.
The code behind looks like
1: public class EmptyDataTemplate : DataTemplate
2: {3: public EmptyDataTemplate()
4: { 5: 6: } 7: 8: public string EmptyHeaderText
9: { 10: get 11: {12: return (string)GetValue(EmptyHeaderTextProperty);
13: } 14: set 15: {16: SetValue(EmptyHeaderTextProperty, value);
17: } 18: } 19: 20: public static readonly DependencyProperty EmptyHeaderTextProperty = DependencyProperty.Register(
21: "EmptyHeaderText", typeof(string), typeof(EmptyDataTemplate), new PropertyMetadata(null));
22: 23: public double Width
24: { 25: get 26: {27: return (double)GetValue(WidthProperty);
28: } 29: set 30: {31: SetValue(WidthProperty, value);
32: } 33: } 34: 35: public static readonly DependencyProperty WidthProperty = DependencyProperty.Register(
36: "Width", typeof(double), typeof(EmptyDataTemplate), new PropertyMetadata(100.0,null));
37: } 38: 39: public class DataGridWithEmptyTemplate : DataGrid
40: { 41: 42: public static TextBlock textBlock = new TextBlock();
43: 44: public DataGridWithEmptyTemplate()
45: { 46: 47: this.Loaded += new RoutedEventHandler((o, e) =>
48: {49: int count = 0;
50: base.ItemsSource = this.ItemsSource;
51: var q = (IEnumerable)base.ItemsSource;
52: if (q != null)
53: {54: foreach (var items in q)
55: { 56: count++; 57: } 58: }59: if (count == 0)
60: {61: EmptyDataTemplate nodeTemplate = (EmptyDataTemplate)this.EmptyTemplate;
62: if (nodeTemplate != null)
63: {64: DataGridTemplateColumn dataGridTemplateColumn = new DataGridTemplateColumn();
65: 66: dataGridTemplateColumn.CellTemplate = nodeTemplate; 67: dataGridTemplateColumn.Header = nodeTemplate.EmptyHeaderText;68: dataGridTemplateColumn.Width = new DataGridLength(nodeTemplate.Width);
69: // we can even display the properties of object binded.
70: //var properties = from propertyInfo in typeof(Person).GetProperties()
71: // select propertyInfo.Name;
72: //foreach (string header in properties)
73: //{
74: // d.Header = d.Header + header + " | ";
75: //}
76: FrameworkElement frameworkElement = dataGridTemplateColumn.CellTemplate.LoadContent() as FrameworkElement;
77: this.Columns.Add(dataGridTemplateColumn);
78: base.ItemsSource = new List<UIElement>() { frameworkElement };
79: base.AutoGenerateColumns = false;
80: } 81: } 82: } 83: ); 84: } 85: 86: public EmptyDataTemplate EmptyTemplate
87: { 88: get 89: {90: return (EmptyDataTemplate)GetValue(EmptyTemplateProperty);
91: } 92: set 93: {94: SetValue(EmptyTemplateProperty, value);
95: } 96: } 97: 98: public static readonly DependencyProperty EmptyTemplateProperty = DependencyProperty.Register(
99: "EmptyTemplate", typeof(EmptyDataTemplate), typeof(DataGridWithEmptyTemplate), new PropertyMetadata(null));
100: 101: }So, even if you forget to assign Itemsource or assigned itemsource which have zero items like before
MyDataGrid.ItemsSource = null;/// or even if you forget to assign Itemsource
MyDataGrid.ItemsSource = new List<Person>();
The result is same as below. You may override the template too!!!
1: <local:DataGridWithEmptyTemplate ItemsSource="{Binding Person}" x:Name="MyDataGrid" AutoGenerateColumns="True">
2: <local:DataGridWithEmptyTemplate.EmptyTemplate>3: <local:EmptyDataTemplate Width="420.0" EmptyHeaderText="FirstName | LastName | Gender " >
4: <Border CornerRadius="5" BorderThickness="2" BorderBrush="Gray" Margin="5" >
5: <Border.Background>6: <LinearGradientBrush EndPoint="0.512,1.154" StartPoint="0.512,0.154">
7: <GradientStop Color="White" Offset="1"/>
8: <GradientStop Color="AntiqueWhite" Offset="0.339"/>
9: </LinearGradientBrush> 10: </Border.Background>11: <StackPanel Width="Auto" Background="Transparent">
12: <TextBlock Text="No Records" Foreground="Red" ></TextBlock>
13: <TextBlock Text="This template may be changed using XAML!!" Foreground="Red"></TextBlock>
14: </StackPanel> 15: </Border> 16: </local:EmptyDataTemplate> 17: </local:DataGridWithEmptyTemplate.EmptyTemplate> 18: </local:DataGridWithEmptyTemplate>
Needless to say, the other functionality of datagrid remain the same as we have only introduced new DPs which have NO impact on existing functionality.
Finally here is the code.
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