Blazor quickgrid error - The supplied expression can't be represented as a property name for sorting

[markat1]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I'm trying to send current chosen sort blazor quickgrid column to my backend.

So when I try to run the the following inside OnInitializedAsync I get an error on GetSortByProperties:

 public GridItemsProvider<TestEntity>? TestCallProvider { get; set; }

      TestCallProvider = async req =>
                {

                    var tq = req;

                    var sortColumn = req.GetSortByProperties();

                    if(req.GetSortByProperties().Any())
                    {
                        var propertyName = sortColumn?.FirstOrDefault().PropertyName; 
                        var direction = sortColumn?.FirstOrDefault().Direction;
                    }

Seems like it has issues with following property in my quickgrid:

1. doesn't seem to like my TimeStamp

<DisplayNameColumn Property="@(p => p.TimeStamp)"
                           Format="dd.MM yy"
                           Sortable="true"
                           InitialSortDirection="SortDirection.Descending"
             
                           IsDefaultSortColumn="true">

which is as nulllable datetime:

  [Display(Name = "Tidspunkt")]
  public DateTime? TimeStamp { get; set; }

displaycolumn looks like this:

 public class DisplayNameColumn<TGridItem, TProp> : PropertyColumn<TGridItem, TProp>
 {
     //protected override void OnParametersSet()
     //{
     //    if (Title is null && Property.Body is MemberExpression memberExpression)
     //    {
     //        var memberInfo = memberExpression.Member;
     //        Title =
     //            memberInfo.GetCustomAttribute<DisplayNameAttribute>()?.DisplayName ??
     //            memberInfo.GetCustomAttribute<DisplayAttribute>()?.GetName() ??
     //            memberInfo.Name;
     //    }

     //    base.OnParametersSet();
     //}

     protected override void OnParametersSet()
     {
         if (Title is null)
         {
             MemberInfo? memberInfo = null;

             if (Property.Body is MemberExpression memberExpression)
             {
                 memberInfo = memberExpression.Member;
             }
             else if (Property.Body is UnaryExpression unaryExpression &&
                      unaryExpression.Operand is MemberExpression unaryMember)
             {
                 memberInfo = unaryMember.Member;
             }

             if (memberInfo != null)
             {
                 Title =
                     memberInfo.GetCustomAttribute<DisplayNameAttribute>()?.DisplayName ??
                     memberInfo.GetCustomAttribute<DisplayAttribute>()?.GetName() ??
                     memberInfo.Name;
             }
         }

         base.OnParametersSet();
     }
 }

Expected Behavior

All I want is the name as string of the column that it current sorting on, with no issues.

Exception

Error I receive is the following issue:

Microsoft.AspNetCore.Components.WebAssembly.Rendering.WebAssemblyRenderer[100]
      Unhandled exception rendering component: The supplied expression can't be represented as a property name for sorting. Only simple member expressions, such as @(x => x.SomeProperty), can be converted to property names.
System.ArgumentException: The supplied expression can't be represented as a property name for sorting. Only simple member expressions, such as @(x => x.SomeProperty), can be converted to property names.
   at Microsoft.AspNetCore.Components.QuickGrid.GridSort`1[[TestProject.Client.Models.TestModelEntity, TestProject.Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].ToPropertyName(LambdaExpression expression)
   at Microsoft.AspNetCore.Components.QuickGrid.GridSort`1[[TestProject.Client.Models.TestModelEntity, TestProject.Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].BuildPropertyList(Boolean ascending)
   at Microsoft.AspNetCore.Components.QuickGrid.GridSort`1[[TestProject.Client.Models.TestModelEntity, TestProject.Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].ToPropertyList(Boolean ascending)
   at Microsoft.AspNetCore.Components.QuickGrid.GridItemsProviderRequest`1[[TestProject.Client.Models.TestModelEntity, TestProject.Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].GetSortByProperties()
   at TestProject.Client.Pages.TestPage.<OnInitializedAsync>b__16_0(GridItemsProviderRequest`1 req) in C:\TestFolder\TestProject\TestProject\TestProject.Client\Pages\TestPage.razor.cs:line 36
   at Microsoft.AspNetCore.Components.QuickGrid.QuickGrid`1.<ResolveItemsRequestAsync>d__83[[TestProject.Client.Models.TestModelEntity, TestProject.Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
   at Microsoft.AspNetCore.Components.QuickGrid.QuickGrid`1.<RefreshDataCoreAsync>d__81[[TestProject.Client.Models.TestModelEntity, TestProject.Client, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null]].MoveNext()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.QuickGrid.Infrastructure.EventCallbackSubscribable`1.<InvokeCallbacksAsync>d__1[[System.Object, System.Private.CoreLib, Version=9.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]].MoveNext()

.NET Version & application

Blazor
.net 9.0

[javiercn]

@markat1 thanks for contacting us.

Problem:
When using Blazor QuickGrid, you receive an error when trying to sort by a nullable property (e.g., DateTime? TimeStamp) via a lambda like @(p => p.TimeStamp). The error says:

The supplied expression can't be represented as a property name for sorting. Only simple member expressions, such as @(x => x.SomeProperty), can be converted to property names.

Root Cause:
The GridSort code in QuickGrid expects the lambda’s expression body to be a MemberExpression. However, for nullable properties, C# may generate a UnaryExpression (due to type conversions) wrapping the MemberExpression. The current implementation does not handle this case and thus throws an exception, even if your usage is correct.

Resolution:
The code needs to be updated to handle both simple MemberExpression and UnaryExpression (with a MemberExpression operand). This will allow sorting on nullable properties.

Conclusion:
The failure is not due to how you define or use DisplayNameColumn or the nullable property, but because QuickGrid’s sorting property extraction doesn’t fully handle nullable property expressions.

[markat1]

thanks for reply @javiercn !

I wasn't able to trigger a scenario where timestamp nodetype was unaryexpression, because expressiontype wasn't either convert or convertcheck

Issue happens to appear when I call GetSortByProperties() on GridItemsProviderRequest<TestEntity> . Then error expression can't be represented as a property name for sorting appears - thing I need is the name of sort column for building up my query.

 public GridItemsProvider<TestEntity>? TestCallProvider { get; set; }


 protected override async Task OnInitializedAsync()
 {
     try
     {

         TestCallProvider = async req =>
         {

             var tq = req;

             try
             {
                 var sortColumn = req.GetSortByProperties().FirstOrDefault();

                 if (req.GetSortByProperties().Any())
                 {
                     var propertyName = sortColumn.PropertyName;
                     var direction = sortColumn.Direction;
                 }


                 var response = await GetDataViaApi();

                 return GridItemsProviderResult.From(response?.ToList() ?? [], response?.Count() ?? 0);

             }
             catch (Exception ex)
             {
                 var t = ex.Message;

                 return GridItemsProviderResult.From<AutoflexEntity>([], 0);
             }


         };
     }
     catch (Exception ex)
     {
         var t = ex.Message;
     }
 }

I can't really see any where in sortByColumn that I can use for receiving property name:

I also tried handeling issue of unary expression by checking if the expression type is convert or convertChecked on parameter set.

Unfortunately still ends up with the same issue - expression can't be represented as a property name for sorting.:

Anyway, I can see you are trying to handle this on https://github.com/dotnet/aspnetcore/pull/62602

protected override void OnParametersSet()
 {
     if (Title is null)
     {
         Expression expressionBody = Property.Body;

         if (expressionBody.NodeType == ExpressionType.Convert ||
             expressionBody.NodeType == ExpressionType.ConvertChecked)
         {
             expressionBody = ((UnaryExpression)expressionBody).Operand;
         }

         if (expressionBody is MemberExpression memberExpression)
         {
             var memberInfo = memberExpression.Member;
             Title =
                 memberInfo.GetCustomAttribute<DisplayNameAttribute>()?.DisplayName ??
                 memberInfo.GetCustomAttribute<DisplayAttribute>()?.GetName() ??
                 memberInfo.Name;
         }
     }
     base.OnParametersSet();
 }

[LimYoungChul]

The issue seems to be in ToPropertyName function in GridSort.cs

private static string ToPropertyName(LambdaExpression expression)
{
        if (expression.Body is not MemberExpression body)
        {
            throw new ArgumentException(ExpressionNotRepresentableMessage);
        }
.....

This part throws an error cause your Property.Body is a UnaryExpression.

private static string ToPropertyName(LambdaExpression expression)
{
       if (expression.Body is not MemberExpression body)
       {
           if (expression.Body is UnaryExpression ue && ue.Operand is MemberExpression unaryMember)
           {
               return unaryMember.Member.Name;
           }
           else
           {
               throw new ArgumentException(ExpressionNotRepresentableMessage);
           }
       }
.....

This could solve the problem i think.

[markat1]

thanks @LimYoungChul, @javiercn pointed out ToPropertyName issue already in his PR .

Issue only appears when I directly call GetSortByProperties() on GridItemsProviderRequest as I mentioned.

Only thing I need is the sorted propertyName, which I would use for building up my sql call