I have this wishlist class:

    public class Wishlist
    {
        public int Id { get; set; }
        public int ProductId { get; set; }
        [ForeignKey("ProductId")]
        public virtual Product Product { get; set; }
        public string PersonId { get; set;}
        [ForeignKey("PersonId")]
        public virtual ApplicationUser Person { get; set; }
    }

    public class Product
    {
        public string Title { get; set; }
        public int CategoryId { get; set; }
        [ForeignKey("CategoryId")]
        public virtual Category Category { get; set; }
        public string Description { get; set; }
        public decimal Price { get; set; }
        public bool Featured { get; set; }
        public bool Sold { get; set; }
        public string Image { get; set; }
        [NotMapped]
        public HttpPostedFileBase UploadImage { get; set; }
        public string PersonId { get; set; }
        [ForeignKey("PersonId")]
        public virtual ApplicationUser Person { get; set; }
    }

I'm trying to get all the products added to dbcontext.Wishlist table, by using:

string currentUserId = User.Identity.GetUserId();
var list2 = DbContext.Wishlist.Where(p => p.PersonId == currentUserId).ToList();
var list3 = (from p in DbContext.Products
             from w in list2
             where p.PersonId == w.PersonId
             select new Models.Response.ProductIndexResponse()
             {
               Id = p.Id,
               Image = p.Image,
               Title = p.Title,
               Price = p.Price
             }).ToList();

But I get this error: Unable to create a constant value of type 'Finder.Models.Wishlist'. Only primitive types or enumeration types are supported in this context.'

What am I doing wrong?

CodePudding user response：

I don't think you can pass the list of WishList to LINQ.

Instead, modify your LINQ query with JOIN as below:

var query = (from p in DbContext.Products
             join w in DbContext.Wishlist on p.PersonId equals w.PersonId
             where p.PersonId == currentUserId
             select new
             {
               Id = p.Id,
               Image = p.Image,
               Title = p.Title,
               Price = p.Price
             }).ToList();

var result = query
    .Select(x => Models.Response.ProductIndexResponse()
    {
        Id = x.Id,
        Image = x.Image,
        Title = x.Title,
        Price = x.Price
    })
    .ToList();

CodePudding user response：

Can you try to simplify you query like this:

var wishPorducts = DbContext.Wishlist
    .Where(p => p.PersonId == currentUserId)
    .Select(x => new Models.Response.ProductIndexResponse()
         {
           Id = x.Product.Id,
           Image = x.Product.Image,
           Title = x.Product.Title,
           Price = x.Product.Price
         })
     .ToList();

The query above is much simpler and efficient and may help you better understand where is the issue if it still there.