How do you rename DataGrid columns when AutoGenerateColumns = True?

Question

I have a simple data structure class:

public class Client {
    public String name {set; get;}
    public String claim_number {set; get;}
}

Which I am feeding into a DataGrid:

this.data_grid_clients.ItemSource = this.clients;

I would like to change the column headings. Ie: claim_number to "Claim Number". I know this can be done when you manually create the columns by doing something like:

this.data_grid_clients.Columns[0].Header = "Claim Number"

However, the Columns property is empty when auto-generating the columns. Is there a way to rename the columns, or do I have to manually generate the columns?

Answer 1

You can use DisplayNameAttribute and update some part of your code to achieve what you want.

The first thing you have to do is, adding a [DisplayName("")] to properties in the Client class.

public class Client {
    [DisplayName("Column Name 1")]
    public String name {set; get;}

    [DisplayName("Clain Number")]
    public String claim_number {set; get;}
}

The update you xaml code, add an event handler to AutoGenerationColumn event.

<dg:DataGrid AutoGenerateColumns="True" AutoGeneratingColumn="OnAutoGeneratingColumn">
</dg:DataGrid>

Finally, add a method to the code-behind.

private void OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    var displayName = GetPropertyDisplayName(e.PropertyDescriptor);

    if (!string.IsNullOrEmpty(displayName))
    {
        e.Column.Header = displayName;
    }

}

public static string GetPropertyDisplayName(object descriptor)
{
    var pd = descriptor as PropertyDescriptor;

    if (pd != null)
    {
        // Check for DisplayName attribute and set the column header accordingly
        var displayName = pd.Attributes[typeof(DisplayNameAttribute)] as DisplayNameAttribute;

        if (displayName != null && displayName != DisplayNameAttribute.Default)
        {
            return displayName.DisplayName;
        }

    }
    else
    {
        var pi = descriptor as PropertyInfo;

        if (pi != null)
        {
            // Check for DisplayName attribute and set the column header accordingly
            Object[] attributes = pi.GetCustomAttributes(typeof(DisplayNameAttribute), true);
            for (int i = 0; i < attributes.Length; ++i)
            {
                var displayName = attributes[i] as DisplayNameAttribute;
                if (displayName != null && displayName != DisplayNameAttribute.Default)
                {
                    return displayName.DisplayName;
                }
            }
        }
    }

    return null;
}

Answer 2

The nice answer

You can modify the Header of the auto generated DataGridColumn header in the AutoGeneratingColumn event, where you can access the DisplayNameAttribute

Client.cs

public class Client
{
    [DisplayName("Name")]
    public String name { set; get; }

    [DisplayName("Claim Number")]
    public String claim_number { set; get; }
}

.xaml

<DataGrid ItemSource="{Binding Clients}"
          AutoGenerateColumns="True"
          AutoGeneratingColumn="DataGrid_AutoGeneratingColumn" />

.xaml.cs

v1

// This snippet can be used if you can be sure that every
// member will be decorated with a [DisplayNameAttribute]
private void DataGrid_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
    => e.Column.Header = ((PropertyDescriptor)e.PropertyDescriptor)?.DisplayName ?? e.Column.Heaader;

v2

// This snippet is much safer in terms of preventing unwanted
// Exceptions because of missing [DisplayNameAttribute].
private void DataGrid_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    if (e.PropertyDescriptor is PropertyDescriptor descriptor)
    {
        e.Column.Header = descriptor.DisplayName ?? descriptor.Name;
    }
}

Answer 3

You can use the AutoGeneratingColumns event.

private void dataGridAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
  if (e.PropertyName.StartsWith("MyColumn")
    e.Column.Header = "Anything I Want";
}

Answer 4

MVVM answer

In order to keep this consistent with the MVVM pattern and avoid using the horrible code-behind, you can use custom behaviors from Sytem.Windows.Interactivity (part of the Expression Blend SDK found on nuget). You also need Windows.Base.dll in the project where you create the behaviors.

XAML

<DataGrid AutoGenerateColumns="True">
    <i:Interaction.Behaviors>
        <behaviours:ColumnHeaderBehaviour/>
    </i:Interaction.Behaviors>
</DataGrid>

Behaviour Class

public class ColumnHeaderBehaviour : Behavior<DataGrid>
{
    protected override void OnAttached()
    {
        AssociatedObject.AutoGeneratingColumn += OnGeneratingColumn;
    }

    protected override void OnDetaching()
    {
        AssociatedObject.AutoGeneratingColumn -= OnGeneratingColumn;
    }

    private static void OnGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs eventArgs)
    {
        if (eventArgs.PropertyDescriptor is PropertyDescriptor descriptor)
        {
            eventArgs.Column.Header = descriptor.DisplayName ?? descriptor.Name;
        }
        else
        {
            eventArgs.Cancel = true;
        }
    }
}

Behaviors are really useful and don't have to be defined in the same project as your views meaning that you can create a library of behaviors and use them in many applications.

Answer 5

The short answer

You can modify the Header of the auto generated DataGridColumn header in the AutoGeneratingColumn event.

.xaml

<DataGrid ItemSource="{Binding Clients}"
          AutoGenerateColumns="True"
          AutoGeneratingColumn="DataGrid_AutoGeneratingColumn" />

.xaml.cs

private void DataGrid_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    switch (e.Name)
    {
        case nameof(Client.name):
            e.Column.Header = "Name";
            break;

        case nameof(Client.claim_number):
            e.Column.Header = "Claim Number";
            break;
    }
}

Answer 6

I refactored the answer of Ekk to a shorter and Resharper compatible solution:

public static string GetPropertyDisplayName(object descriptor)
{
   var propertyDescriptor = descriptor as PropertyDescriptor;
   if (propertyDescriptor != null)
   {
      var displayName = propertyDescriptor.Attributes[typeof(DisplayNameAttribute)] as DisplayNameAttribute;
      if (displayName != null && !Equals(displayName, DisplayNameAttribute.Default))
      {
         return displayName.DisplayName;
      }
   }
   else
   {
      var propertyInfo = descriptor as PropertyInfo;
      if (propertyInfo != null)
      {
         var attributes = propertyInfo.GetCustomAttributes(typeof(DisplayNameAttribute), true);
         foreach (object attribute in attributes)
         {
            var displayName = attribute as DisplayNameAttribute;
            if (displayName != null && !Equals(displayName, DisplayNameAttribute.Default))
            {
               return displayName.DisplayName;
            }
         }
      }
   }
   return null;
}

Answer 7

Another Method of Generating Column Headers

To add upon what others have stated in the context of attaching to the OnAutoGeneratingColumn method; I find the following approach useful.

It will assure that it uses the DisplayName attribute from a view model property just like the others, but if that name is not set it will use regular expressions to take a Pascal cased name and turn it into a nice column header.

 //Note that I cleaned this up after I pasted it into the Stackoverflow Window, I don't
 //think I caused any compilation errors but you have been warned.
 private void InvoiceDetails_OnAutoGeneratingColumn(object sender,
                                                    DataGridAutoGeneratingColumnEventArgs e)
 {
     if (!(e.PropertyDescriptor is PropertyDescriptor descriptor)) return;

     //You cannot just use descriptor.DisplayName because it provides you a value regardless to it 
     // being manually set.  This approach only uses a DisplayName that was manually set on a view
     // model property.  
     if (descriptor.Attributes[typeof(DisplayNameAttribute)] 
                    is DisplayNameAttribute displayNameAttr
                    && !string.IsNullOrEmpty(displayNameAttr.DisplayName))
     {
         e.Column.Header = displayNameAttr.DisplayName;
         return;
     }

     //If you only wanted to display columns that had DisplayName set you could collapse the ones
     // that didn't with this line.
     //e.Column.Visibility = Visibility.Collapsed;
     //return;

     //This alternative approach uses regular expressions and does not require 
     //DisplayName be manually set.  It will Breakup Pascal named variables 
     //"NamedLikeThis" into nice column headers that are "Named Like This".
     e.Column.Header = Regex.Replace(descriptor.Name,
             @"((?<=[A-Z])([A-Z])(?=[a-z]))|((?<=[a-z]+)([A-Z]))",
             @" $0",
             RegexOptions.Compiled)
            .Trim();

 }