How to use Kendo UI Grid with ToDataSourceResult(), IQueryable<T>, ViewModel and AutoMapper?

Question

What is the best approach to load/filter/order a Kendo grid with the following classes:

Domain:

public class Car
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual bool IsActive { get; set; }
}

ViewModel

public class CarViewModel
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual string IsActiveText { get; set; }
}

AutoMapper

Mapper.CreateMap<Car, CarViewModel>()
      .ForMember(dest => dest.IsActiveText, 
                 src => src.MapFrom(m => m.IsActive ? "Yes" : "No"));

IQueryable

var domainList = RepositoryFactory.GetCarRepository().GetAllQueryable();

DataSourceResult

var dataSourceResult = domainList.ToDataSourceResult<Car, CarViewModel>(request, 
                          domain => Mapper.Map<Car, ViewModel>(domain));

Grid

...Kendo()
  .Grid<CarViewModel>()
  .Name("gridCars")
  .Columns(columns =>
  {
     columns.Bound(c => c.Name);
     columns.Bound(c => c.IsActiveText);
  })
  .DataSource(dataSource => dataSource
     .Ajax()
     .Read(read => read.Action("ListGrid", "CarsController"))
  )
  .Sortable()
  .Pageable(p => p.PageSizes(true))

Ok, the grid loads perfectly for the first time, but when I filter/order by IsActiveText I get the following message:

Invalid property or field - 'IsActiveText' for type: Car

What is the best approach in this scenario?

Answer 1

František's solution is very nice! But be careful with casting Filters to FilterDescriptor. Some of them can be composite.

Use this implementation of DataSourceRequestExtensions instead of František's:

public static class DataSourceRequestExtensions
{
    /// <summary>
    /// Enable flattened properties in the ViewModel to be used in DataSource.
    /// </summary>
    public static void Deflatten(this DataSourceRequest dataSourceRequest)
    {
        DeflattenFilters(dataSourceRequest.Filters);

        foreach (var sortDescriptor in dataSourceRequest.Sorts)
        {
            sortDescriptor.Member = DeflattenString(sortDescriptor.Member);
        }
    }

    private static void DeflattenFilters(IList<IFilterDescriptor> filters)
    {
        foreach (var filterDescriptor in filters)
        {
            if (filterDescriptor is CompositeFilterDescriptor)
            {
                var descriptors
                    = (filterDescriptor as CompositeFilterDescriptor).FilterDescriptors;
                DeflattenFilters(descriptors);
            }
            else
            {
                var filter = filterDescriptor as FilterDescriptor;
                filter.Member = DeflattenString(filter.Member);
            }
        }
    }

    private static string DeflattenString(string source)
    {
        return source.Replace('_', '.');
    }
}

Answer 2

I don't like the way Kendo has implemented "DataSourceRequestAttribute" and "DataSourceRequestModelBinder", but thats another story.

To be able to filter/sort by VM properties which are "flattened" objects, try this:

Domain model:

public class Administrator
{
    public int Id { get; set; }

    public int UserId { get; set; }

    public virtual User User { get; set; }
}

public class User
{
    public int Id { get; set; }

    public string UserName { get; set; }

    public string Email { get; set; }
}

View model:

public class AdministratorGridItemViewModel
{
    public int Id { get; set; }

    [Displaye(Name = "E-mail")]
    public string User_Email { get; set; }

    [Display(Name = "Username")]
    public string User_UserName { get; set; }
}

Extensions:

public static class DataSourceRequestExtensions
{
    /// <summary>
    /// Enable flattened properties in the ViewModel to be used in DataSource.
    /// </summary>
    public static void Deflatten(this DataSourceRequest dataSourceRequest)
    {
        foreach (var filterDescriptor in dataSourceRequest.Filters.Cast<FilterDescriptor>())
        {
            filterDescriptor.Member = DeflattenString(filterDescriptor.Member);
        }

        foreach (var sortDescriptor in dataSourceRequest.Sorts)
        {
            sortDescriptor.Member = DeflattenString(sortDescriptor.Member);
        }
    }

    private static string DeflattenString(string source)
    {
        return source.Replace('_', '.');
    }
}

Attributes:

[AttributeUsage(AttributeTargets.Method)]
public class KendoGridAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        base.OnActionExecuting(filterContext);

        foreach (var sataSourceRequest in filterContext.ActionParameters.Values.Where(x => x is DataSourceRequest).Cast<DataSourceRequest>())
        {
            sataSourceRequest.Deflatten();
        }
    }
}

Controller action for Ajax data load:

[KendoGrid]
public virtual JsonResult AdministratorsLoad([DataSourceRequestAttribute]DataSourceRequest request)
    {
        var administrators = this._administartorRepository.Table;

        var result = administrators.ToDataSourceResult(
            request,
            data => new AdministratorGridItemViewModel { Id = data.Id, User_Email = data.User.Email, User_UserName = data.User.UserName, });

        return this.Json(result);
    }

Answer 3

Something about that seems weird. You told Kendo UI to make a grid for CarViewModel

.Grid<CarViewModel>()

and told it there is an IsActive column:

columns.Bound(c => c.IsActive);

but CarViewModel doesn't have a column by that name:

public class CarViewModel
{
    public virtual int Id { get; set; }
    public virtual string Name { get; set; }
    public virtual string IsActiveText { get; set; }
}

My guess is that Kendo is passing up the field name from the CarViewModel IsActiveText, but on the server you are running ToDataSourceResult() against Car objects (an IQueryable<Car>), which do not have a property by that name. The mapping happens after the filtering & sorting.

If you want the filtering and sorting to happen in the database, then you would need to call .ToDataSourceResult() on the IQueryable before it runs against the DB.

If you have already fetched all your Car records out of the DB, then you can fix this by doing your mapping first, then calling .ToDataSourceResult() on an IQueryable<CarViewModel>.

Answer 4

I followed the suggestion of CodingWithSpike and it works. I created an extension method for the DataSourceRequest class:

public static class DataSourceRequestExtensions
    {
        /// <summary>
        /// Finds a Filter Member with the "memberName" name and renames it for "newMemberName".
        /// </summary>
        /// <param name="request">The DataSourceRequest instance. <see cref="Kendo.Mvc.UI.DataSourceRequest"/></param>
        /// <param name="memberName">The Name of the Filter to be renamed.</param>
        /// <param name="newMemberName">The New Name of the Filter.</param>
        public static void RenameRequestFilterMember(this DataSourceRequest request, string memberName, string newMemberName)
        {
            foreach (var filter in request.Filters)
            {
                var descriptor = filter as Kendo.Mvc.FilterDescriptor;
                if (descriptor.Member.Equals(memberName))
                {
                    descriptor.Member = newMemberName;
                }
            } 
        }
    }

Then in your controller, add the using to the extension class and before the call to ToDataSourceResult(), add this:

request.RenameRequestFilterMember("IsActiveText", "IsActive");