Asp.net core PaginatedList with view model - entity-framework

Question

I would like to use PaginatedList with ViewModel , and send multiple entities in the view model.
When I tried this I got this error :
The provider for the source 'IQueryable' doesn't implement 'IAsyncQueryProvider'. Only providers that implement 'IAsyncQueryProvider' can be used for Entity Framework asynchronous operations.
This is my view model
public class GalleryViewModel
{
public IEnumerable<ProjectPic> ProjectPics { get; set; }
public IEnumerable<CoursePic> CoursePics { get; set; }
}
PaginatedList (from Microsoft docs)
public class PaginatedList<T> : List<T>
{
public int PageIndex { get; private set; }
public int TotalPages { get; private set; }
public PaginatedList(List<T> items, int count, int pageIndex, int pageSize)
{
PageIndex = pageIndex;
TotalPages = (int)Math.Ceiling(count / (double)pageSize);
this.AddRange(items);
}
public bool HasPreviousPage
{
get
{
return (PageIndex > 1);
}
}
public bool HasNextPage
{
get
{
return (PageIndex < TotalPages);
}
}
public static async Task<PaginatedList<T>> CreateAsync(IQueryable<T> source, int pageIndex, int pageSize)
{
var count = await source.CountAsync();
var items = await source.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToListAsync();
return new PaginatedList<T>(items, count, pageIndex, pageSize);
}
}
Code behind
[HttpGet]
public async Task<IActionResult> Gallery(Guid Id, string currentFilter, string searchString, int? pageNumber = 1)
{
ViewData["CurrentFilter"] = searchString;
var projectsPics = await _projectPic.Entity.GetAll().Include(a => a.Project).ThenInclude(a => a.ApplicationUser).AsNoTracking().ToListAsync();
var vm = new List<GalleryViewModel>();
{
new GalleryViewModel { ProjectPics = projectsPics };
};
var mock = vm.AsQueryable();
int pageSize = 4;
return View(await PaginatedList<GalleryViewModel>.CreateAsync(mock, pageNumber ?? 1, pageSize));
}
In razor view
#model PaginatedList<GalleryViewModel>

Answer 1

Well the problem is in this line: var mock = vm.AsQueryable();. You can't do that. You are casting a List<GalleryViewModel> to a default IQueryable which has nothing in common with the IQueryable implementation Entity Framework is expecting (DbSet).
You'll have to use DbSet<Gallery> property or something similar that you have in your DbContext to make that query.