Bring back DbQuery<T>

In EF Core 2.2, we used a query type similar to this (notice the Id property):

public sealed class Record
{
    public int Id { get; set; }
    public string Value { get; set; }
}

that wasn’t mapped to anything - not a table, not a view. We only used it with FromSql(). In our DbContext we had:

public DbQuery<Record> Records { get; set; }

After upgrading to EF Core 3.0, I see that DbQuery is marked as obsolete, suggesting the use of DbSet instead. I was a little confused, because - how will EF Core then be able to tell that this isn’t actually supposed to be an entity… only a query type? And of course after running this, EF Core suddenly treated it as an entity and wanted to create a table for Records.

I saw a suggestion to mitigate this by configuring the type using HasNoKey(). That didn’t work. EF Core still wanted to create a table for it. So I tried a few other things - calling ToTable(null) since we don’t want a table, but that threw an exception. Eventually I tried using ToView (even though we don’t want to map this to any view) and calling ToView(null) finally did the trick.

My question is: why the deprecation of DbQuery<T>?

The docs says:

This change was made to reduce the confusion around the purpose of query types.

In my opinion, the previous behavior was really clear and unambiguous - in our DbContext, we had DbSet<T> and DbQuery<T> properties. You could immediately see what was an actual entity mapped to a table in the database (DbSet) and what was not (DbQuery).

Now, I can’t tell by looking at the DbContext itself. Instead of a simple change in the type of a property, I have to add additional configuration for the type to prevent it from being treated as an entity and mapped to a table, in a way that’s not intuitive at all. I find the current state much more confusing than before.

[loth0]

@ErikEJ Sorry my bad, now I found that a OnModelCreatingPartial method is generated, that one does the trick, thanks a lot!

[cda-1]

@ajcvickers

What is the reason you need to DbSet properties for these types on your DbContext?

We don’t. I think the author wrote it that way to avoid having to use fluent configuration (which we now have to use anyway to prevent EF Core from trying to create a table for it but at the same time be able to use it in FromSql). So yes, now it’s pointless, I’ll remove them, thanks.

I’m following this thread and the exchange between @Neme12 and @ajcvickers, but I don’t understand this part. Is the DbSet property still (in .net core 3.1) required if we are using .FromSql()?

I am still using FromSql, so I’ll still need the DbSet item, and .HasNoKey() and .ToView(null), right?

I created a Stack Overflow Question about this.