C#•3y ago

Entity Framework One-To-One [Answered]

Code at: https://paste.mod.gg/rccwzntafwoj/0 When attempting to change the database I'm getting: The dependent side could not be determined for the one-to-one relationship between 'Room.Vet' and 'Vet.Room'. To identify the dependent side of the relationship, configure the foreign key property. If these navigations should not be part of the same relationship, configure them independently via separate method chains in 'OnModelCreating'. See http://go.microsoft.com/fwlink/?LinkId=724062 for more details. OR The property 'Room.Vet' is of type 'Vet' which is not supported by the current database provider. Either change the property CLR type, or ignore the property using the '[NotMapped]' attribute or by using 'EntityTypeBuilder.Ignore' in 'OnModelCreating'. I wanted to be able to create a Room that can have 0 or 1 Vets, and create a Vet that has 0 or 1 Rooms. What am I doing incorrectly? Thanks in advance.

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Relationships - EF Core

How to configure relationships between entity types when using Entity Framework Core

12 Replies

Angius•3y ago

You need to define the relationship explicitly

builder.Entity<One>()
    .HasOne(o => o.Two)
    .WithOne(t => t.One);

builder.Entity<One>()
    .HasOne(o => o.Two)
    .WithOne(t => t.One);

Might need .HasForeignKey() as well

pyrodisticOP•3y ago

I was currently doing:

            modelBuilder.Entity<Vet>()
                .HasOne(s => s.Room).WithOne(s => s.Vet)
                .IsRequired(false);

            modelBuilder.Entity<Room>()
                .HasOne(s => s.Vet).WithOne(s => s.Room)
                .IsRequired(false);

            modelBuilder.Entity<Vet>()
                .HasOne(s => s.Room).WithOne(s => s.Vet)
                .IsRequired(false);

            modelBuilder.Entity<Room>()
                .HasOne(s => s.Vet).WithOne(s => s.Room)
                .IsRequired(false);

Which prompts the second error when trying to submit changes.

Angius•3y ago

Configure only one side of the relationship, it's enough

pyrodisticOP•3y ago

Thank you, understood, but it continues with the same error (the first one).

Angius•3y ago

What's your config now?

pyrodisticOP•3y ago

Same that's on the link for code so:

public class DataContext : IdentityDbContext<User>
    {
        public DataContext(DbContextOptions<DataContext> options) : base(options)
        {
        }

        public DbSet<Room> Rooms { get; set; }
        public DbSet<Vet> Vets { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Vet>()
                .HasOne(s => s.Room).WithOne(s => s.Vet)
                .IsRequired(false);
        }
    }

public class DataContext : IdentityDbContext<User>
    {
        public DataContext(DbContextOptions<DataContext> options) : base(options)
        {
        }

        public DbSet<Room> Rooms { get; set; }
        public DbSet<Vet> Vets { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Vet>()
                .HasOne(s => s.Room).WithOne(s => s.Vet)
                .IsRequired(false);
        }
    }

Angius•3y ago

Still no .HasForeignKey<T>() I see The docs you linked talk about it as well

Angius•3y ago

pyrodisticOP•3y ago

I might be wrong, please tell me but I thing the .HasForeignKey() makes it so it cannot be nullable, or is that completely incorrect?

Angius•3y ago

That's incorrect .IsRequired() is what sets it Also, make the key nullable just to make sure So not public int VetId { get; set; } but public int? VetId { get; set; } for example

pyrodisticOP•3y ago

Shouldn't have assumed that .HasForeignKey() determined requirement. Thank you so much!

Accord•3y ago

✅ This post has been marked as answered!

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Entity Framework One-To-One [Answered]