Using automapper with PagedList.mvc

Question

I am trying to convert to using ViewModels in my mvc4 application. I have successfully switched my POST actions to use viewmodels, but in the below example, I am trying to use both automapper and PagedList in an action.

I have made a class called AutoMapperConfiguration (below) to avoid adding mapping throughout the application:

public class AutoMapperConfiguration
{
    public static void Configure()
    {
        ConfigureItemMapping();
    }

    public class PagedListConverter : ITypeConverter<PagedList<Item>,PagedList<ItemListViewModel>>
    {
        public PagedList<ItemListViewModel> Convert(ResolutionContext context)
        {
            var model = (PagedList<Item>)context.SourceValue;
            var vm = model.Select(m => Mapper.Map<Item, ItemListViewModel>(m)).ToPagedList(model.PageNumber,model.PageSize);

            return new PagedList<ItemListViewModel>(vm,model.PageNumber,model.PageSize);
        }
    }

    private static void ConfigureItemMapping()
    {
        Mapper.CreateMap<ItemListViewModel,Item>();
        Mapper.CreateMap<PagedList<Item>, PagedList<ItemListViewModel>>()
            .ConvertUsing<PagedListConverter>();
    }
}

The above is called from Global.asax

 protected void Application_Start()
     {
       ...
       AutoMapperConfiguration.Configure();
       ...
     }

From the controller, I am trying to send a list of items to the itemViewModel from the item Model as a Paged List. This is where I have become completely stuck. Needless to say the below doesn't work.

[HttpGet]
        public ActionResult Index(int page = 1)
        {
            //Show 10 items per page for the Admin
            int pageSize = 10;

            var items = new PagedList<Item>(
                        db.Items.OrderBy(i => i.ItemId),page,pageSize);
            var vm = new ItemListViewModel();

            Mapper.Map<PagedList<Item>, PagedList<ItemListViewModel>>(items);

            return View(vm);
        }

Error now being seen is:

Missing type map configuration or unsupported mapping.

Mapping types: Item -> ItemListViewModel Project.Models.Item -> Project.ViewModels.ItemListViewModel

Destination path: ItemListViewModel

It is being thrown on the following line in the PagedListConverter

 var vm = model.Select(m => Mapper.Map<Item, ItemListViewModel>(m)).ToPagedList(model.PageNumber,model.PageSize);

Any help would be appreciated.

Answer 1

I would create a PagedList<Item> manually and then map to a PagedList<ItemViewModel>:

[HttpGet]
public ActionResult Index(int page = 1)
{
    int pageSize = 20;

    var vm = new ItemListViewModel();
    var items = new PagedList(
        db.Items.OrderBy(i => i.ItemId),
        page,
        pageSize);

    var viewModels = Mapper.Map<PagedList<Item>, PagedList<ItemListViewModel>>(items);

    return View(viewModels);
}

Then it also seems like your converter needs some tweaks too. It should probably take the page number and size from the source PagedList:

public class PagedListConverter : ITypeConverter<PagedList<Item>,PagedList<ItemListViewModel>>
{
    public PagedList<ItemListViewModel> Convert(ResolutionContext context)
    {
        var model = (PagedList<Item>)context.SourceValue;
        var vm = model.Select(m => Mapper.Map<Item, ItemListViewModel>(m)).ToList();

        return new PagedList<ItemListViewModel>(vm, model.PageNumber, model.PageSize);
    }
}

Also make sure to use your custom converter when you call CreateMap:

Mapper.CreateMap<PagedList<Item>, PagedList<ItemViewModel>>()
    .ConvertUsing<PagedListConverter>();

You also need a map from Item to ItemViewModel:

Mapper.CreateMap<Item, ItemListViewModel>();

Answer 2

Generic solution in AutoMapper 6+:

TypeConverter:

public class PagedListConverter<TSource, TDestination> : ITypeConverter<PagedList<TSource>, PagedList<TDestination>> where TSource : class where TDestination : class
{
    public PagedList<TDestination> Convert(PagedList<TSource> source, PagedList<TDestination> destination, ResolutionContext context)
    {
        var collection = Mapper.Map<IEnumerable<TSource>, IEnumerable<TDestination>>(source.Value);

        return new PagedList<TDestination>(collection, source.Page, source.Size, source.TotalCount);
    }
}

Initialize:

CreateMap(typeof(PagedList<>), typeof(PagedList<>)).ConvertUsing(typeof(PagedListConverter<,>));

Example:

var vm = Mapper.Map<PagedList<User>, PagedList<UserViewModel>>(users);

UPDATE:

If u are using dependency injection (IMapper), then replace the static class Mapper with the context.Mapper.Map...

var collection = context.Mapper.Map<IEnumerable<TSource>, IEnumerable<TDestination>>(source.Items);