https://docs.telerik.com/blazor-ui/components/grid/editing/incell#notes 

I am using an EditorTemplate with a method called ChangeHandler(). After clicking in another row everything works fine but if I leave the cell by pressing enter the UpdateHandler gets called more than two times and comparing args.Item with the GridItem doesn't help because the calls are asynchronous.

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Admin Edit

With 2.22.0, the InCell editing mode was revamped to provide better user experience and this alters the way it worked. In the common case, there will no longer be double OnUpdate calls (unless explicit application logic invokes them). With 2.23.0, Tab and Enter keys that bubble from editor templates will be handled by the grid like they are handled for the built-in editors.

This means that this issue is, effectively, solved. You can see the Notes section about editor templates to see how you can also handle the OnBlur event to capture mouse clicks outside of the component so that you can save changes and remove the edited item. See the full notes here (the Event Sequence section was heavily revamped for clarity) and here on editor template behavior.

Thus, the previous ides about  Save and Cancel methods on the edit context might not be implemented, which will also be one breaking change that we could avoid:

After discussion with the development team, the proposed resolution is to provide a context that provides Save/Cancel operations. The goal is to provide easier configuration for IncellEditing and EditorTemplates and consistent behavior with mouse and keyboard interaction. However, the change will introduce a breaking change in our EditorTemplate, should be researched further and that is why this is logged as a feature request.

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This will let Excel mark the field as a Date and act according to the current culture on the machine that opens the file.

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ADMIN EDIT:

This feature would let you define custom formats, so you may want to Vote for it and Follow it too: Custom Format for Excel Export per column. It is important to keep in mind that the Excel formats are completely different from the .NET formats.

If this is of high importance for you right now, you could create your own Excel file with the desired settings by following the example from this thread.

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On initialization of the Grid the oDataString is correct, but when I apply a filter or apply a sort to a Grid column the ToODataString extension method generates an incorrect request URL. If I revert back to 2.16.0 everything works as expected. 

On initialization of the Grid the oDataString is correct, but when I apply a Filter (through the FilterMenu) or apply a sort to a Grid column the ToODataString extension method throws with null reference exception. If the FilterMode is set to FilterRow or revert back to 2.16.0 everything works as expected. 

<AdminEdit>

This bug extends to the functionality of the FilterMenu as a feature and is not connected only to the ToODataString();

</AdminEdit>

It will be useful if the grid column state contains the Field parameter if such is specified.

This will make easier mapping the ColumnState entity to the actual column.

I am using EF on my backend and when I group I get an error like this one:

Unhandled exception rendering component: Processing of the LINQ expression '(GroupByShaperExpression:
      KeySelector: (t.FirstName), 
      ElementSelector:(EntityShaperExpression: 
          EntityType: Customer
          ValueBufferExpression: 
              (ProjectionBindingExpression: EmptyProjectionMember)
          IsNullable: False
      )
      )' by 'RelationalProjectionBindingExpressionVisitor' failed. This may indicate either a bug or a limitation in EF Core. See https://go.microsoft.com/fwlink/?linkid=2101433 for more detailed information.
System.InvalidOperationException: Processing of the LINQ expression '(GroupByShaperExpression:
KeySelector: (t.FirstName), 
ElementSelector:(EntityShaperExpression: 
    EntityType: Customer
    ValueBufferExpression: 
        (ProjectionBindingExpression: EmptyProjectionMember)
    IsNullable: False
)
)' by 'RelationalProjectionBindingExpressionVisitor' failed. This may indicate either a bug or a limitation in EF Core. See https://go.microsoft.com/fwlink/?linkid=2101433 for more detailed information.
   at Microsoft.EntityFrameworkCore.Query.Internal.RelationalProjectionBindingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)

and a lot more line through the EF Core expression classes.

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ADMIN EDIT

    protected override void OnInitialized()
    {
        GridData = ProductService.GetProducts().ToList();
    }

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I want to customize the appearance of the header of a certain column, and a bit of CSS backgrounds could help, but I can't do this with the HeaderTemplate alone, nor with content in it because of the padding the cells have.

So, I would like the ability to set the CSS class of the header cell of the column.

At the moment, the CollapsedGroups  collection in the grid state is the indexes of the root-level groups that you can collapse. I want to also be able to control the expanded state of nested groups.

ADMIN EDIT:

Ideas I can see are the following, do add your vote and comments on how you expect that to be exposed:

• a form of Id/field in the group descriptor that controls this. Caveat - groups don't generally have such an id and the descriptor does not control the UI, it controls the data.
• an event that provides the level, field name and group value that lets me choose this for every group as it renders. Caveat - might not plug in the state, but if you have a certain business logic for that you can just keep it in that event always, regardless of the grid state, or keep additional information in an application state.
• the current indexes could become recursive (see the image attached below). Caveat: you can't be sure that the next time data loads the data and so the groups will be the same when loading state

it would be helpful to have the ability to set Class attribute for rendered TD.

this would allow for example to set a background color for a column

For example, when I have two levels of grouping, I want to render only the inner footer templates, but not the outer.

While this is possible with some CSS like the snippet below, this does not scale well, and does not work well for arbitrary number of groups

<style>
    .k-group-footer + .k-group-footer {
       display:none;
    }
</style>

Group by the Vacation and Team columns to see the effect

<TelerikGrid Data=@GridData Groupable="true" Pageable="true">
    <GridColumns>
        <GridColumn Field=@nameof(Employee.Name) Groupable="false" />
        <GridColumn Field=@nameof(Employee.Team) Title="Team">
            <GroupFooterTemplate>
                Team group footer
            </GroupFooterTemplate>
        </GridColumn>
        <GridColumn Field=@nameof(Employee.IsOnLeave) Title="On Vacation">
            <GroupFooterTemplate>
                IsOnLeave group footer
            </GroupFooterTemplate>
            </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    public List<Employee> GridData { get; set; }

    protected override void OnInitialized()
    {
        GridData = new List<Employee>();
        var rand = new Random();
        for (int i = 0; i < 15; i++)
        {
            GridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3,
                IsOnLeave = i % 2 == 0
            });
        }
    }

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public string Team { get; set; }
        public bool IsOnLeave { get; set; }
    }
}

If I add an await-ed call in the OnRowClick handler, then I cannot alter the grid state later in the code. It only works if the method is called again (e.g., a second click on the same row).

<AdminEdit>

This affects other Grid events too, for example, the PageChanged

</AdminEdit>

A workaround is to use synchronous code (remove the await call):

@inject IJSRuntime JsInterop

<TelerikGrid Data="@salesTeamMembers" OnRowClick="@OnRowClickHandler" @ref="@GridRef">
    <DetailTemplate>
        @{
            var employee = context as MainModel;
            <TelerikGrid Data="employee.Orders" Pageable="true" PageSize="5">
                <GridColumns>
                    <GridColumn Field="OrderId"></GridColumn>
                    <GridColumn Field="DealSize"></GridColumn>
                </GridColumns>
            </TelerikGrid>
        }
    </DetailTemplate>
    <GridColumns>
        <GridColumn Field="Id"></GridColumn>
        <GridColumn Field="Name"></GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    List<MainModel> salesTeamMembers { get; set; }
    TelerikGrid<MainModel> GridRef { get; set; }

    async Task OnRowClickHandler(GridRowClickEventArgs args) {
        // After adding this line, it now requires a double click when the InvokeAsync call uses "await"
         var width = JsInterop.InvokeAsync<int>("getWidth");


        var model = args.Item as MainModel;
        int index = salesTeamMembers.IndexOf(model);
        //todo: you may want to take paging into account for example, or use js interop to get the index of the row based on contents from it like id
        if (index > -1) {
            var state = GridRef.GetState();
            state.ExpandedRows = new List<int> { index };

            await GridRef.SetState(state);
        }

    }


    protected override void OnInitialized() {
        salesTeamMembers = GenerateData();
    }

    private List<MainModel> GenerateData() {
        List<MainModel> data = new List<MainModel>();
        for (int i = 0; i < 5; i++) {
            MainModel mdl = new MainModel { Id = i, Name = $"Name {i}" };
            mdl.Orders = Enumerable.Range(1, 15).Select(x => new DetailsModel { OrderId = x, DealSize = x ^ i }).ToList();
            data.Add(mdl);
        }
        return data;
    }

    public class MainModel {
        public int Id { get; set; }
        public string Name { get; set; }
        public List<DetailsModel> Orders { get; set; }
    }

    public class DetailsModel {
        public int OrderId { get; set; }
        public double DealSize { get; set; }
    }
}

Sample reproducible with workaround (to initialize the data source so it is not null) is below

Sample error and stack trace

<TelerikGrid Data=@GridData Pageable="true" Height="300px">
    <GridColumns>
        <GridColumn Field="@(nameof(Employee.EmployeeId))">
            <FooterTemplate>
                some footer
            </FooterTemplate>
        </GridColumn>
        <GridColumn Field=@nameof(Employee.Salary) Title="Salary">
        </GridColumn>
        <GridColumn Field=@nameof(Employee.Name)>
        </GridColumn>
    </GridColumns>
</TelerikGrid>

@code {
    public List<Employee> GridData { get; set; } // = new List<Employee>(); // workaround

    public class Employee
    {
        public int EmployeeId { get; set; }
        public string Name { get; set; }
        public decimal Salary { get; set; }
    }
}

I want to edit the Excel file the grid exports before it gets to the user. For example, to add a sheet with data I want to generate, or to change columns, formats, colors.

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ADMIN EDIT

I have attached to this post an example that shows how you can generate your own exported file so you can customize colors, sheets and so on. It also shows how to cache the DataSourceRequest of the grid so you can extract only the current page or all data, and so you can also apply the current grid sorts/filters and so on to the export. This also lets you add metadata to the sheet such as the current user settings such as filters that resulted in this filter.

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I want to be able to enter numbers and the grid to filter numeric fields too according to those numbers. Enums would be nice too.

**Admin Edit**

The feature request will be researched and evaluated. It contradicts to our datasource filtering logic that relies on the type of the fields. Thus, it is highly possible that we will handle the task through a knowledge base example.

**Admin Edit**