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Problem with the following error in EF Cannot insert the value NULL into column 'Discriminator

cdpace asked:

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Hi Everyone,

I have the following poco class in library.
public class Product
   {
       [Key]
       public long ID { get; set; }
       public string Name { get; set; }
       public int? StockQuantity { get; set; }
       [Column(TypeName="nvarchar")]
       [MaxLength(50)]
       public string Identifier { get; set; }
       public DateTime? ReleaseDate { get; set; }
       public decimal? DefaultPrice { get; set; }
       public virtual ICollection<Language> ProductLanguages { get; set; }
       public virtual ICollection<Region> ProductRegions { get; set; }
       public virtual ICollection<Price> ProductPrices { get; set; }
       public virtual ICollection<Link> ProductLinks { get; set; }
       public virtual ICollection<Order> Orders { get; set; }
   }


and I have serveral other poco classes referencing this class like the below

public class Link
    {
        [Key]
        public Int32 ID { get; set; }
        public string Rel { get; set; }
        public string Href { get; set; }

        public virtual ICollection<Product> LinkProducts { get; set; }
    }


I am also using database migrations with the -EnableAutomaticMigrations flag.

My problem is when I call the method SaveChanges() in my DataContext I get the following error message.

"Cannot insert the value NULL into column 'Discriminator'

I know that this means that EF thinks that there is some class that is derives from product but this isn't true.

Can you please help with this problem?

Thank you,
Tags: C# (C#4.0), entity-framework

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