EF Code First "Invalid column name 'Discriminator'" but no inheritance

Question

I have a table in my database called SEntries (see below the CREATE TABLE statement). It has a primary key, a couple of foreign keys and nothing special about it. I have many tables in my database similar to that one, but for some reason, this table ended up with a "Discriminator" column on the EF Proxy Class. This is how the class is declared in C#: ``` public class SEntry { public long SEntryId { get; set; } public long OriginatorId { get; set; } public DateTime DatePosted { get; set; } public string Message { get; set; } public byte DataEntrySource { get; set; } public string SourceLink { get; set; } public int SourceAppId { get; set; } public int? LocationId { get; set; } public long? ActivityId { get; set; } public short OriginatorObjectTypeId { get; set; } } public class EMData : DbContext { public DbSet<SEntry> SEntries { get; set; } ... } ``` When I try to add a new row to that table, I get the error: ``` System.Data.SqlClient.SqlException: Invalid column name 'Discriminator'.…

Accepted Answer

Turns out that Entity Framework will assume that any class that inherits from a POCO class that is mapped to a table on the database requires a Discriminator column, even if the derived class will not be saved to the DB.

The solution is quite simple and you just need to add `[NotMapped]` as an attribute of the derived class.

Example:

```
class Person
{
    public string Name { get; set; }
}

[NotMapped]
class PersonViewModel : Person
{
    public bool UpdateProfile { get; set; }
}
```

Now, even if you map the Person class to the Person table on the database, a "Discriminator" column will not be created because the derived class has `[NotMapped]`.

As an additional tip, you can use `[NotMapped]` to properties you don't want to map to a field on the DB.

EF Code First "Invalid column name 'Discriminator'" but no inheritance

Solution

Problem