Values from previously selected row

[Larry]

Is it possible to capture field value (namely Id) from a selected row in a grid when selecting a different row?  I read a post that sounded like using some kind of leave event is probably impractical as a feature request but that templates can be used along with StateChanged events.  I've been experimenting with that but I seem to only be able to get an Id from the current row selected, and I also need to retain the Id from the last row that was selected prior to selecting a different row.

[John]

hook up to the rowselect event, have a variable "selectedRow" and update/compare that in that method?

[Larry]

That's along the lines of what I'm attempting.  So far I'm only able to pull the Id value of the currently selected row.  It seems that I need to figure out how retain the Id from the previously selected row into some kind of temp storage in order to make the comparison.  I don't have the option of using something like a 'BeforeRowSelect' to retain the old value to use for comparison before it's overridden with current row selected.

With that in mind I'm still a long way from getting proficient with Blazor and the Telerik grid so I'm hoping that there is a fairly easy trick for something like this. 

[Nadezhda Tacheva]

Hi Larry,

Here is an example of how to achieve the desired behavior using the approach suggested by John. You can use a variable to store the previous selection and use it where needed - see the code comments for more details.

 

<h6>Selected: @CurrSelectedEmployee.Name</h6>
<h6>Last Selected: @LastSelectedEmployee.Name</h6>


<TelerikGrid Data=@GridData
             SelectionMode="GridSelectionMode.Single"
             SelectedItemsChanged="@((IEnumerable<Employee> employeeList) => OnSelect(employeeList))"
             SelectedItems="@SelectedItems"
             Pageable="true"
             Height="300px">
    <GridColumns>
        <GridColumn Field=@nameof(Employee.Name) />
        <GridColumn Field=@nameof(Employee.Team) Title="Team" />
    </GridColumns>
</TelerikGrid>

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

    public IEnumerable<Employee> SelectedItems { get; set; } = Enumerable.Empty<Employee>();

    public Employee CurrSelectedEmployee { get; set; } = new Employee();

    public Employee LastSelectedEmployee { get; set; } = new Employee();

    protected void OnSelect(IEnumerable<Employee> employees)
    {
        //store the selection in a variable and do not update it with the value from the SelectedItemsChanged EventCallback
        LastSelectedEmployee = CurrSelectedEmployee;

        //update the current selection with the value from the SelectedItemsChanged EventCallback
        CurrSelectedEmployee = employees.FirstOrDefault();

        // update the collection so that the grid can highlight the correct item
        // when two-way binding is used this happens automatically, but the framework does not allow two-way binding and the event at the same time
        SelectedItems = new List<Employee> { CurrSelectedEmployee };
    }

    //data generation and model
    protected override async Task OnInitializedAsync()
    {

        GridData = new List<Employee>();
        for (int i = 0; i < 15; i++)
        {
            GridData.Add(new Employee()
            {
                EmployeeId = i,
                Name = "Employee " + i.ToString(),
                Team = "Team " + i % 3
            });
        }
    }

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

 

If any further questions appear after reviewing and testing the above snippet, please do not hesitate to contact us.

Regards,
Nadezhda Tacheva
Progress Telerik