Windows Presentation Foundation
A part of the .NET Framework that provides a unified programming model for building line-of-business desktop applications on Windows.
2,710 questions
DataGrid.Columns[i].GetCellContent(Item) returns null (C#)
رضا جافری
1,296
Reputation points
First and foremost, I apologize for my grammatical errors; my first language is Persian (Iran).
I use the following method to calculate the total price and it works fine at first, but when I change the DataGrid.ItemsSource, line 27 returns a null error.
Note: EnableRowVirtualization must be set to false.
XAML:
<DataGrid x:Name="BookDataGrid" ContextMenu="{StaticResource DataGridContextMenu}" HeadersVisibility="Column" EnableRowVirtualization="False" AutoGenerateColumns="False" ItemsSource="{Binding}" HorizontalAlignment="Left" VerticalAlignment="Top" Width="486" Height="386" Margin="0">
<DataGrid.Columns>
<DataGridTextColumn x:Name="BookName" Binding="{Binding BookName}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Publisher" Binding="{Binding Publisher}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Category" Binding="{Binding Category}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="BookCode" Binding="{Binding BookCode}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Inventory" Binding="{Binding Inventory}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="DateTaken" Binding="{Binding DateTaken}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="RecipientName" Binding="{Binding RecipientName}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="ReturnDate" Binding="{Binding ReturnDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="ReleaseDate" Binding="{Binding ReleaseDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Language" Binding="{Binding BookLanguage}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Length" Binding="{Binding Length}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Form" Binding="{Binding Form}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Translator" Binding="{Binding Translator}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Narrator" Binding="{Binding Narrator}"/>
<DataGridTextColumn x:Name="ISBN" Binding="{Binding ISBN}"/>
<DataGridTextColumn x:Name="Location" Binding="{Binding Location}"/>
<DataGridTextColumn x:Name="Price" Binding="{Binding Price}"/>
<DataGridTemplateColumn x:Name="BookImage" Width="SizeToHeader">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Image x:Name="BookImg" Source="{Binding BookImage}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
C#:
public string GetDigit(string Text)
{
string Digit = null;
switch (Text)
{
case "":
break;
default:
for (byte i = 0; i < Text.Length && i <= 255; i++)
{
switch (char.IsDigit(Text[i]))
{
case true:
Digit += Text[i];
break;
}
}
break;
}
return Digit;
}
public void TotalPrice()
{
ulong Total = 0;
for (int i = 0; i < BookDataGrid.Items.Count - 1; i++)
{
Total += (ulong.Parse(GetDigit((BookDataGrid.Columns[16].GetCellContent(BookDataGrid.Items[i]) as TextBlock).Text)));
}
TotalPrice_TextBox.Text = ulong.Parse(Total.ToString().Replace(",", "")).ToString("n0");
}
I use the following method to remove item from DataGrid.ItemsSource and it works fine:
Output:
private void DataGridDeleteMenu_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
List<object> DefaultRow = new List<object>();
for (int i = 0; i < BookDataGrid.Items.Count - 1; i++)
{
DefaultRow.Add(BookDataGrid.Items[i]);
}
for (int i = 0; i < BookDataGrid.SelectedItems.Count; i++)
{
DefaultRow.Remove(BookDataGrid.SelectedItems[i]);
}
BookDataGrid.ItemsSource = DefaultRow;
//Retrying to use the TotalPrice method returns a null error
TotalPrice();
}
Note: In the Window Loaded event, the TotalPrice method works fine, but
Returns a null error when I try to use it again (after changing the DataGrid.ItemsSource).
XAML (definitions of Books_GroupBox & Members_GroupBox):
<GroupBox x:Name="Books_GroupBox" Header="Books" Background="Transparent" Visibility="Hidden" HorizontalAlignment="Center" Width="500" Height="400" VerticalAlignment="Center">
<GroupBox.Style>
<Style TargetType="{x:Type GroupBox}">
<Setter Property="BorderBrush" Value="DarkGray"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type GroupBox}">
<Grid SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Border BorderBrush="DarkGray"
BorderThickness="1"
CornerRadius="9"
Grid.ColumnSpan="4"
Grid.RowSpan="4">
<Border.OpacityMask>
<MultiBinding ConverterParameter="9">
<MultiBinding.Converter>
<BorderGapMaskConverter/>
</MultiBinding.Converter>
<Binding ElementName="Header" Path="ActualWidth"/>
<Binding Path="ActualWidth" RelativeSource="{RelativeSource Self}"/>
<Binding Path="ActualHeight" RelativeSource="{RelativeSource Self}"/>
</MultiBinding>
</Border.OpacityMask>
</Border>
<Border x:Name="Header" Grid.RowSpan="1" Grid.ColumnSpan="2" Margin="9,-11.5,0,0" HorizontalAlignment="Left" VerticalAlignment="Top">
<ContentPresenter ContentSource="Header"
RecognizesAccessKey="True"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</Border>
<ContentPresenter Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1"
Margin="{TemplateBinding Padding}"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</GroupBox.Style>
<ItemsControl Width="486" Height="386" Margin="-118,-93,-118,-193">
<Grid DataContext="{StaticResource BookTableViewSource}" Width="486" Height="386">
<DataGrid x:Name="BookDataGrid" ContextMenu="{StaticResource DataGridContextMenu}" HeadersVisibility="Column" EnableRowVirtualization="False" AutoGenerateColumns="False" ItemsSource="{Binding}" HorizontalAlignment="Left" VerticalAlignment="Top" Width="486" Height="386" Margin="0">
<DataGrid.Columns>
<DataGridTextColumn x:Name="BookName" Binding="{Binding BookName}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Publisher" Binding="{Binding Publisher}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Category" Binding="{Binding Category}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="BookCode" Binding="{Binding BookCode}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Inventory" Binding="{Binding Inventory}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="DateTaken" Binding="{Binding DateTaken}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="RecipientName" Binding="{Binding RecipientName}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="ReturnDate" Binding="{Binding ReturnDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="ReleaseDate" Binding="{Binding ReleaseDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Language" Binding="{Binding BookLanguage}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Length" Binding="{Binding Length}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Form" Binding="{Binding Form}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Translator" Binding="{Binding Translator}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Narrator" Binding="{Binding Narrator}"/>
<DataGridTextColumn x:Name="ISBN" Binding="{Binding ISBN}"/>
<DataGridTextColumn x:Name="Location" Binding="{Binding Location}"/>
<DataGridTextColumn x:Name="Price" Binding="{Binding Price}"/>
<DataGridTemplateColumn x:Name="BookImage" Width="SizeToHeader">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Image x:Name="BookImg" Source="{Binding BookImage}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
</Grid>
</ItemsControl>
</GroupBox>
<GroupBox x:Name="Members_GroupBox" Header="Members" Background="Transparent" Visibility="Visible" HorizontalAlignment="Center" Width="500" Height="400" VerticalAlignment="Center">
<GroupBox.Style>
<Style TargetType="{x:Type GroupBox}">
<Setter Property="BorderBrush" Value="DarkGray"/>
<Setter Property="BorderThickness" Value="1"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type GroupBox}">
<Grid SnapsToDevicePixels="true">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Border BorderBrush="DarkGray"
BorderThickness="1"
CornerRadius="9"
Grid.ColumnSpan="4"
Grid.RowSpan="4">
<Border.OpacityMask>
<MultiBinding ConverterParameter="9">
<MultiBinding.Converter>
<BorderGapMaskConverter/>
</MultiBinding.Converter>
<Binding ElementName="Header" Path="ActualWidth"/>
<Binding Path="ActualWidth" RelativeSource="{RelativeSource Self}"/>
<Binding Path="ActualHeight" RelativeSource="{RelativeSource Self}"/>
</MultiBinding>
</Border.OpacityMask>
</Border>
<Border x:Name="Header" Grid.RowSpan="1" Grid.ColumnSpan="2" Margin="9,-11.5,0,0" HorizontalAlignment="Left" VerticalAlignment="Top">
<ContentPresenter ContentSource="Header"
RecognizesAccessKey="True"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</Border>
<ContentPresenter Grid.ColumnSpan="2" Grid.Column="1" Grid.Row="1"
Margin="{TemplateBinding Padding}"
SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</GroupBox.Style>
<ItemsControl Width="486" Height="386" Margin="-118,-93,-118,-193">
<Grid DataContext="{StaticResource MemberTableViewSource}" Width="486" Height="386">
<DataGrid x:Name="MemberDataGrid" HeadersVisibility="Column" EnableRowVirtualization="False" AutoGenerateColumns="False" ItemsSource="{Binding}" HorizontalAlignment="Left" VerticalAlignment="Top" Width="486" Height="386" Margin="0">
<DataGrid.Columns>
<DataGridTextColumn x:Name="FirstName" Binding="{Binding FirstName}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="LastName" Binding="{Binding LastName}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="DateOfBirth" Binding="{Binding DateOfBirth}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="IDNumber" Binding="{Binding IDNumber}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="PhoneNumber" Binding="{Binding PhoneNumber}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="MobilePhoneFirstNumber" Binding="{Binding MobilePhoneFirstNumber}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="MobilePhoneSecondNumber" Binding="{Binding MobilePhoneSecondNumber}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="LoanDate" Binding="{Binding LoanDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="NumberOfBooksBorrowed" Binding="{Binding NumberOfBooksBorrowed}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="NamesOfBorrowedBooks" Binding="{Binding NamesOfBorrowedBooks}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="BookReturnDate" Binding="{Binding BookReturnDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="MembershipDate" Binding="{Binding MembershipDate}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="RegistrationFee" Binding="{Binding RegistrationFee}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="QR" Binding="{Binding QR}" Width="auto"/>
<DataGridTextColumn x:Name="Credit" Binding="{Binding Credit}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Debt" Binding="{Binding Debt}" Width="SizeToHeader"/>
<DataGridTextColumn x:Name="Description" Binding="{Binding Description}" Width="SizeToHeader"/>
<DataGridTemplateColumn x:Name="MemberImage" Width="SizeToHeader">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Image x:Name="MemberImg" Source="{Binding MemberImage}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
</Grid>
</ItemsControl>
</GroupBox>
Thanks
Windows Presentation Foundation
C#
C#
An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.
10,648 questions
XAML
XAML
A language based on Extensible Markup Language (XML) that enables developers to specify a hierarchy of objects with a set of properties and logic.
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Hui Liu-MSFT 47,341 Reputation points Microsoft Vendor2022-03-22T07:19:30.83+00:00 Hi,@RezaJafery. Could you show me the complete code of your DataGrid ContextMenu to reproduce the problem?
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رضا جافری 1,296 Reputation points
2022-03-22T08:50:47+00:00 Hi, HuiLiu I could not update my question: You don't have permission to access "http://learn.microsoft.com/answers/answers/780667/post.html" on this server.
Reference #18.172b3517.1647938925.11fbaad1 -
رضا جافری 1,296 Reputation points
2022-03-22T08:51:40.267+00:00 XAML (DataGridContextMenu):
<ContextMenu x:Key="DataGridContextMenu" Style="{StaticResource ContextMenuStyle}"> <MenuItem x:Name="DataGridCopyMenu" Style="{StaticResource MenuItem}" Header="Copy" Command="Copy" Height="32" Cursor="Hand"/> <MenuItem x:Name="DataGridCutMenu" Style="{StaticResource MenuItem}" Header="Cut" Command="Cut" Height="32" Cursor="Hand"/> <MenuItem x:Name="DataGridPasteMenu" Style="{StaticResource MenuItem}" Header="Paste" Command="Paste" Height="32" Cursor="Hand"/> <Separator/> <MenuItem x:Name="DataGridDeleteMenu" PreviewMouseLeftButtonDown="DataGridDeleteMenu_PreviewMouseLeftButtonDown" Style="{StaticResource MenuItem}" Header="Delete" Height="32" Cursor="Hand"/> </ContextMenu> -
رضا جافری 1,296 Reputation points
2022-03-22T09:05:40.62+00:00 C# (DataGridContextMenu):
-
رضا جافری 1,296 Reputation points
2022-03-22T09:13:40.317+00:00 I could not update my question, so I sent you the code as Image (I hope the pictures are readable).
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Hui Liu-MSFT 47,341 Reputation points Microsoft Vendor
2022-03-23T07:55:19.627+00:00 Hi,@RezaJafery .What are the definitions of your Books_GroupBox , MessageWindow and MemberDataGrid? Could you show me the minimal code that reproduces the problem or a download link of the minimal project to analyze?
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رضا جافری 1,296 Reputation points
2022-03-23T09:32:01.603+00:00 I updated my question, the
MessageWindowis a standalone (class) window that shows the message to the user.
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