EF Core 7 Rev eng: Missing HasForeignKey when referencing a navigation property with a unique constraint with DataAnnotations on

[ErikEJ]

File a bug

Using EF Core 7 SQL Server reverse engineering with "Use Data annotations" enabled, the foreignkey configuration is missing.

See description and link to repro schema here: ErikEJ/EFCorePowerTools#1554

@bricelam

EF Core version: 7.0 RC2
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET 6
Operating system: Windows

[bricelam]

@AndriySvyryd Is it by design that this model creates a new Car.ColorCode1 property (instead of just using the existing ColorCode property) for the relationship?

class TestContext : DbContext
{
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Car>().HasOne(d => d.Color).WithMany(p => p.Cars)
            .HasPrincipalKey(p => p.ColorCode);
    }
}

class Car
{
    public int Id { get; set; }

    public string? ColorCode { get; set; }
    public virtual Color? Color { get; set; }
}

class Color
{
    public int Id { get; set; }

    public string ColorCode { get; set; } = null!;
    public virtual ICollection<Car> Cars { get; } = new List<Car>();
}

[AndriySvyryd]

Yes, we only match these patterns:

• [navigation property name][principal key property name]
• [navigation property name]Id
• [principal entity name][principal key property name]
• [principal entity name]Id

[ajcvickers]

@AndriySvyryd In that case, why do we create a foreign key name by convention (ColorCode--the principal key name) that by default isn't something we match? That seems inconsistent--if we don't match it, we shouldn't create the thing we don't match.

[TimKras]

I just wanted to add that this problem only occurs in EF Core 7 (RC).
It is working fine in EF Core 6.

[AndriySvyryd]

@ajcvickers Because naming it ColorColorCode looked wrong. However, using the same logic for FK discovery might be unexpected. But we could consider using it as long as it doesn't match PK properties.

[ajcvickers]

Notes from triage: ideally, the rules would not result in this behavior. However, rather than making the rules even more complex we decided that it would be better here for scaffolding to respect the existing rules, as it did in EF Core 6.0.l

[ErikEJ]

No plan to fix for 7.0??

[ajcvickers]

@ErikEJ We are going to consider patching.

[bricelam]

Stranger and stranger...

Trying to configure it with an attribute doesn't work.

// Still not used. Still get shadow property 'ColorCode1'
public string? ColorCode { get; set; }

[ForeignKey(nameof(ColorCode))]
public virtual Color? Color { get; set; }

[ajcvickers]

What did 6.0 scaffold?

[bricelam]

Scaffold? It never scaffolded data annotations when the principal key is non-primary. It always used fluent API.

But I'm just playing with model building to see which data annotations we can scaffold. I'll just work around the [ForeignKey] bug for now, and we can address it separately.

[bricelam]

Filed #29448

[TimKras]

@ajcvickers will this be patched in version 7? If so, is it possible to give an estimation on the timing?

[ajcvickers]

@TimKras Possibly, although you are the only person to have reported it so far, so right now it might not meet the customer impact bar required for a servicing fix.

[ajcvickers]

Note from triage: this issue covers a wider range of cases than initially thought; we should patch.

[bricelam]

🩹 Workaround

I may be stating the obvious here, but one workaround is to not use data annotations when scaffolding. Or, you can manually add HasForeignKey to the scaffolded code after its generated.

[TimKras]

🩹 Workaround

I may be stating the obvious here, but one workaround is to not use data annotations when scaffolding. Or, you can manually add HasForeignKey to the scaffolded code after its generated.

A better temporary workaround is adding the missing HasForeignKey in the OnModelCreatingPartial method, so it not overridden each time the context is scaffold:

partial void OnModelCreatingPartial(ModelBuilder modelBuilder)
{
     modelBuilder.Entity<Car>().HasOne(d => d.Color).WithMany(p => p.Cars)
        .HasForeignKey(p=>p.ColorCode)
        .HasPrincipalKey(p => p.ColorCode);
}

[TimKras]

Confirmed fixed in 7.0.3