无法使用LINQ从数据库检索记录

Question

I am trying to retrieve a record for an update using below

var product= _db.Products.SingleOrDefault(x => x.Id == id);
if (product!= null)
{
    product.StatusId = statusId;
    _db.SaveChanges();
}

Product Model

public int Id { get; set; }
public int TypeId { get; set; }
public int? CategoryId { get; set; }
public int? StatusId { get; set; }
public string Name { get; set; }
public ProductStatus Status { get; set; }
public ICollection<ProductStatus> ProductStatuses { get; set; }

But, while retrieving the record in the first line, it throws an exception saying {"Invalid column name 'ProductStatus_Id'."} I do have a ProductStatus table but not sure if it has anything to do with it

Answer 1

Your model doesn't specify a foreign key to the ProductStatus table, so it is trying to use EF's default convention, which is to look for a field called "ProductStatus_Id".

You can fix it by either adding a column called ProductStatus_Id to the Products table (and make it a FK to ProductStatus ), or you can use a data annotation to specify a name (and also have a matching column).

Or, if you don't need Product.ProductStatus , remove the property from Product (which you could do temporarily to test.

Edit: This page (first google hit for "ef foreign key", no affiliation) has some examples http://www.entityframeworktutorial.net/code-first/foreignkey-dataannotations-attribute-in-code-first.aspx