Entity Framework 5 Code-First Many-to-Many Table Inherited Class Reassignment (TPC)
Good. I am having some problems with the Entity framework when trying to specify the name of the join tables like this:
// Used by a bunch of things...
public abstract BaseClass
{
public int Id { get; set; }
public string Name { get; set; }
}
public abstract ThingsBaseClass : BaseClass
{
public virtual ICollection<Things> Things { get; set; }
}
public First : ThingsBaseClass
{
// This holds items of type First and doesn't have any other properties
}
public Second : ThingsBaseClass
{
// This holds items of type Second and doesn't have any other properties
}
public Things
{
public int Id { get; set; }
public string Description { get; set; }
// Many to Many
public virtual ICollection<First> Firsts { get; set; }
public virtual ICollection<Second> Seconds { get; set; }
}
So everything works fine except for the following tables:
First
FirstThings
Second
SecondThings
Things
I am trying to rename to:
First
Second
ThingFirsts
ThingSeconds
Things
Trying to rename them using the following code gives some very strange and random errors:
public class ThingConfiguration : EntityTypeConfiguration<Thing>
{
HasMany(x => x.Firsts)
.WithMany(x => x.Things)
.Map(x => x.ToTable("ThingFirsts"));
HasMany(x => x.Firsts)
.WithMany(x => x.Things)
.Map(x => x.ToTable("ThingSeconds"));
}
I am trying to use First First Migrations to update a database (or just create one from scratch)
Errors include some of the following:
Schema specified is not valid. Errors:
(28,6) : error 0040: Type Thing_First is not defined in namespace Project.Domain.Repositories (Alias=Self).
or
Schema specified is not valid. Errors:
(126,6) : error 0074: NavigationProperty 'Thing' is not valid. Type 'Project.Domain.Repositories.Second' of FromRole 'Thing_Firsts_Target' in AssociationType 'Project.Domain.Repositories.Thing_Second' must exactly match with the type 'Project.Domain.Repositories.First' on which this NavigationProperty is declared on.
If I get rid of the inheritance of First and Second and directly put in Id
, Name
and ICollection<Thing> Things
, it works without issue.
There is no reason to use inheritance, other than that I have about 5 of these objects that have almost identical BaseClass
es and want to keep it DRY.
Should I just bite the bullet and repeat the code all over the place to make it easier for Entity Framework?
Am I missing something simple? Any other "received". Will I run into using inherited classes?
Does EF 6 have this support?
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I would just use the attribute in the class definition of the model.
[TableName("WhateverYouWant")]
public class First{}
You might want to consider "preference composition over inheritance" and treat shared values as a property instead of a base class, and use an interface to handle them polymorphically. DRY is important, but more important for behavior. Two objects with the same properties should not automatically result in a base class, it is more likely that two classes with the same behavior are. Inheritance and other object-oriented methodologies are about normalizing behavior, not normalizing data and properties. After all 2 classes implementing the same interface will have duplicate property definitions; this is normal.
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