实体框架中是否不支持通用类作为模型？

Question

I am trying to do something like this :

public class TrackerContext : DbContext
{
    public bool TrackNewValues { get; set; }

    public TrackerContext(bool trackNewValues = false)
        : base()
    {
        TrackNewValues = trackNewValues;
    }

    public TrackerContext(string connectinString, bool trackNewValues = false)
        : base(connectinString)
    {
        TrackNewValues = trackNewValues;
    }

    public DbSet<AuditLog<string>> AuditLog { get; set; }
    public DbSet<AuditLogChild> LogChildren { get; set; }
}



public class AuditLog<UserIdOrUserNameColumnType>
{
    public AuditLog()
    {
        Children = new List<AuditLogChild>();
    }

    [Key]
    public Guid AuditLogID { get; set; }

    public UserIdOrUserNameColumnType UserId { get; set; }

    [Required]
    public DateTimeOffset EventDateUTC { get; set; }
}

But I guess DbSet<AuditLog<string>> is not supported. I get this error:

Additional information: The type 'TrackerEnabledDbContext.AuditLog`1[System.String]' was not mapped. Check that the type has not been explicitly excluded by using the Ignore method or NotMappedAttribute data annotation. Verify that the type was defined as a class, is not primitive or generic, and does not inherit from EntityObject.

Is there any ways I can implement public DbSet<AuditLog<string>> AuditLog { get; set; } public DbSet<AuditLog<string>> AuditLog { get; set; } public DbSet<AuditLog<string>> AuditLog { get; set; } ?

Answer 1

You cannot map the generic type because Entity Framework simply doesn't support generic Entity types. When using the EF Code-First approach you need to remember that you should model your POCO classes within the constraints that allow Entity Framework to create POCO proxies .

This means, shortly speaking that such a class:

• Should not contain any attributes
• Should not be generic
• Should be public
• Must not be sealed
• Must not be abstract
• Must have a public or protected constructor that does not have parameters

Answer 2

I have been using generic classes with success in Entity Framework. If you declare your class and DbSet the following way it will work.

public class AuditLogString : AuditLog<String>{}

public DbSet<AuditLogString>  AuditLogStrings { get;set;}

[Update] I have not used this method recently and in the light of the comments on this answer I suggest Pawel's answer instead. However I have not deleted this answer since I was able to use the method.