Custom ASPNET Identity one to many relationship using multiple context application

问题

Basically, I want to have a user that can create their own stories.

I have these classes:

public class ApplicationUser : IdentityUser
{
  public string DisplayedName { get; set; }
}

public class Story
{
  public int Id { get; set; }
  public string Content { get; set; }
}

They are managed on a different context and so as their migration. Something like this.

public class MyDbContext : DbContext
{
  public DbSet<Story> Stories { get; set; }
}

public class IdentityContext : IdentityDbContext<ApplicationUser>
{
}

When I try to add a migration then update them individually, it works fine but when I try to add a collection of stories in my application user.

public class ApplicationUser : IdentityUser
{
  public string DisplayedName { get; set; }
  public virtual ICollection<Story> Stories { get; set; }
}

public class Story
{
  public int Id { get; set; }
  public string Content { get; set; }
  public string WrittenById { get; set; }
  public virtual ApplicationUser WrittenBy { get; set; }
}

public class StoryMap : EntityTypeConfiguration<Story>
{
  public StoryMap()
  {
    HasOptional(s => s.WrittenBy)
      .WithMany(s => s.Stories)
      .HasForeignKey(s => s.WrittenById)
      .WillCascadeOnDelete(false);
  }
}

Then do a migration on my Story entity using the contenxt of MyDbContext it fails saying.

Data.IdentityUserLogin: : EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType.
Data.IdentityUserRole: : EntityType 'IdentityUserRole' has no key defined. Define the key for this EntityType.
IdentityUserLogins: EntityType: EntitySet 'IdentityUserLogins' is based on type 'IdentityUserLogin' that has no keys defined.
IdentityUserRoles: EntityType: EntitySet 'IdentityUserRoles' is based on type 'IdentityUserRole' that has no keys defined.

But when I try the other way around in which I'll do a migration using the IdentityContext it would create a new table of Story

For now, what works is merging my contexts. Something like.

public class MyDbContext : IdentityDbContext<ApplicationUser>
{
  public DbSet<Story> Stories { get; set; }
}

But there must be a way of managing them separately, right? Or am I doing it all wrong?

回答1:

You can't reference entities from one context in another, or that context will attempt to manage those entities as well, resulting in errors about tables already existing. You have two options:

If you don't actually need two separate contexts (i.e., they're both Code First and you're fine with everything being in one database), then the best and easiest solution is to just merge them as you've done. There's no benefit to having multiple contexts, and as you've seen, there's plenty of detriment. The only good reason to ever use multiple contexts is if you're dealing with additional existing databases.
Create a simple column to store the related id (not a foreign key). You lose the optimization of having a true foreign key and the ability to lazy load, but you can still at least somewhat relate things this way. Essentially, you just set this property with the id of the related object in the other context. Then, when you need to retrieve that object, you just issue a query with that other context, utilizing that id. In other words, you just manually fetch the objects.

That's your only options, unfortunately.

来源：https://stackoverflow.com/questions/36018140/custom-aspnet-identity-one-to-many-relationship-using-multiple-context-applicati

标签

asp.net-mvc

entity-framework

asp.net-identity