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 lt SEntry gt  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     This problem only occurs if you are inheriting your C  class from another class  but SEntry is not inheriting from anything  as you can see above    In addition to that  once I get the tool-tip on the debugger when I mouse over the EMData instance for the SEntries property  it displays   base  System Data Entity Infrastructure DbQuery lt EM SEntry gt      SELECT   Extent1   Discriminator  AS  Discriminator     Extent1   SEntryId  AS  SEntryId     Extent1   OriginatorId  AS  OriginatorId     Extent1   DatePosted  AS  DatePosted     Extent1   Message  AS  Message     Extent1   DataEntrySource  AS  DataE      Any suggestions or ideas where to get to the bottom of this issue  I tried renaming the table  the primary key and a few other things  but nothing works   SQL-Table   CREATE TABLE  dbo   SEntries    SEntryId   bigint  IDENTITY 1125899906842624 1  NOT NULL   OriginatorId   bigint  NOT NULL   DatePosted   datetime  NOT NULL   Message   nvarchar  500  NOT NULL   DataEntrySource   tinyint  NOT NULL   SourceLink   nvarchar  100  NULL   SourceAppId   int  NOT NULL   LocationId   int  NULL   ActivityId   bigint  NULL   OriginatorObjectTypeId   smallint  NOT NULL  CONSTRAINT  PK SEntries  PRIMARY KEY CLUSTERED     SEntryId  ASC  WITH  PAD INDEX    OFF  STATISTICS NORECOMPUTE    OFF  IGNORE DUP KEY   OFF        ALLOW ROW LOCKS    ON  ALLOW PAGE LOCKS    ON  ON  PRIMARY    ON  PRIMARY   GO  ALTER TABLE  dbo   SEntries   WITH CHECK ADD  CONSTRAINT  FK SEntries ObjectTypes  FOREIGN KEY  OriginatorObjectTypeId   REFERENCES  dbo   ObjectTypes    ObjectTypeId   GO  ALTER TABLE  dbo   SEntries  CHECK CONSTRAINT  FK SEntries ObjectTypes  GO  ALTER TABLE  dbo   SEntries   WITH CHECK ADD  CONSTRAINT  FK SEntries SourceApps  FOREIGN KEY  SourceAppId   REFERENCES  dbo   SourceApps    SourceAppId   GO  ALTER TABLE  dbo   SEntries  CHECK CONSTRAINT  FK SEntries SourceApps  GO

User · 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.

User · Answer

I get the error in another situation  and here are the problem and the solution   I have 2 classes derived from a same base class named LevledItem   public partial class Team   LeveledItem        Everything is ok here    public partial class Story   LeveledItem        Everything is ok here      But in their DbContext  I copied some code but forget to change one of the class name   public class MFCTeamDbContext   DbContext       protected override void OnModelCreating DbModelBuilder modelBuilder                  Other codes here         modelBuilder Entity lt LeveledItem gt                 Map lt Team gt  m   gt  m Requires  Type   HasValue ItemType Team           public class ProductBacklogDbContext   DbContext       protected override void OnModelCreating DbModelBuilder modelBuilder                  Other codes here         modelBuilder Entity lt LeveledItem gt                 Map lt Team gt  m   gt  m Requires  Type   HasValue ItemType Story            Yes  the second Map lt  Team  should be Map lt  Story    And it cost me half a day to figure it out

User · Answer

Here is the Fluent API syntax   http   blogs msdn com b adonet archive 2010 12 06 ef-feature-ctp5-fluent-api-samples aspx  class Person       public string FirstName   get  set        public string LastName   get  set        public string FullName            get               return this FirstName         this LastName                     class PersonViewModel   Person       public bool UpdateProfile   get  set        protected override void OnModelCreating DbModelBuilder modelBuilder           ignore a type that is not mapped to a database table     modelBuilder Ignore lt PersonViewModel gt             ignore a property that is not mapped to a database column     modelBuilder Entity lt Person gt             Ignore p   gt  p FullName

User · Answer

Old Q  but for posterity   it also also happens   NET Core 2 1  if you have a self-referencing navigation property   Parent  or  Children  of the same type  but the Id property name isn t what EF expects  That is  I had an  Id  property on my class called WorkflowBase  and it had an array of related child steps  which were also of type WorkflowBase  and it kept trying to associate them with a non-existent  WorkflowBaseId   the name i suppose it prefers as a natural conventional default   I had to explicitly configure it using HasMany    WithOne    and HasConstraintName   to tell it how to traverse  But I spent a few hours thinking the problem was in  locally  mapping the object s primary key  which i attempted to fix a bunch of different ways but which was probably always working

User · Answer

I had a similar problem  not exactly the same conditions and then i saw this post  Hope it helps someone  Apparently i was using one of my EF entity models a base class for a type that was not specified as a db set in my dbcontext  To fix this issue i had to create a base class that had all the properties common to the two types and inherit from the new base class among the two types   Example     Bad Flow       class defined in dbcontext as a dbset     public class Customer          public int Id  get  set          public string Name  get  set                class not defined in dbcontext as a dbset     public class DuplicateCustomer Customer          public object DuplicateId  get  set                 Good Correct flow        Common base class     public class CustomerBase          public int Id  get  set          public string Name  get  set                entity model referenced in dbcontext as a dbset     public class Customer  CustomerBase                entity model not referenced in dbcontext as a dbset     public class DuplicateCustomer CustomerBase          public object DuplicateId  get  set

User · Answer

this error happen with me because I did the following    I changed Column name of table in database   I did not used Update Model from database in Edmx  I Renamed manually Property name to match the change in database schema    I did some refactoring to change name of the property in the class to be the same as database schema and models in Edmx   Although all of this  I got this error  so what to do    I Deleted the model from Edmx Right Click and Update Model from database   this will regenerate the model  and entity framework will not give you this error  hope this help you

User · Answer

I just encountered this and my problem was caused by having two entities both with the System ComponentModel DataAnnotations Schema TableAttribute referring to the same table   for example    Table  foo    public class foo          some stuff here     Table  foo    public class fooExtended          more stuff here     changing the second one from foo to foo extended fixed this for me and I m now using Table Per Type  TPT

User · Answer

Another scenario where this occurs is when you have a base class and one or more subclasses  where at least one of the subclasses introduce extra properties   class Folder      key    public string Id   get  set       public string Name   get  set          Adds no props  but comes from a different view in the db to Folder  class SomeKindOfFolder  Folder         Adds some props  but comes from a different view in the db to Folder  class AnotherKindOfFolder  Folder     public string FolderAttributes   get  set        If these are mapped in the DbContext like below  the   Invalid column name  Discriminator   error occurs when any type based on Folder base type is accessed   protected override void OnModelCreating DbModelBuilder modelBuilder      modelBuilder Entity lt Folder gt    ToTable  All Folders      modelBuilder Entity lt SomeKindOfFolder gt    ToTable  Some Kind Of Folders      modelBuilder Entity lt AnotherKindOfFolder gt    ToTable  Another Kind Of Folders        I found that to fix the issue  we extract the props of Folder to a base class  which is not mapped in OnModelCreating    like so - OnModelCreating should be unchanged   class FolderBase      key    public string Id   get  set       public string Name   get  set       class Folder  FolderBase      class SomeKindOfFolder  FolderBase      class AnotherKindOfFolder  FolderBase     public string FolderAttributes   get  set        This eliminates the issue  but I don t know why

[entity-framework] EF Code First "Invalid column name 'Discriminator'" but no inheritance

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