C#•3d ago

✅ [solved] efcore owned entity issue

modelBuilder.Entity<A>(aBuilder =>
        {
            aBuilder.HasKey("Id");
            aBuilder.Property<Guid>("Id");

            aBuilder.OwnsMany<B>(
                "bList",
                bBuilder =>
                {
                    bBuilder.HasKey("Id"); // Without it Ef core sets pair (AId, Id) as key but it is not needed - only one key (Id) is enough
                    bBuilder.Property<Guid>("Id");
                    bBuilder.Property<Guid>("AId").HasColumnName("AId");
                    bBuilder.WithOwner().HasForeignKey("AId");

                    bBuilder.OwnsOne<C>(b => b.C, cBuilder =>
                    {
                        cBuilder.Property<Guid>("Id");
                        cBuilder.Property<Guid>("BId").HasColumnName("BId");
                        cBuilder.WithOwner().HasForeignKey("BId");
                    });
                }
            );
        });

modelBuilder.Entity<A>(aBuilder =>
        {
            aBuilder.HasKey("Id");
            aBuilder.Property<Guid>("Id");

            aBuilder.OwnsMany<B>(
                "bList",
                bBuilder =>
                {
                    bBuilder.HasKey("Id"); // Without it Ef core sets pair (AId, Id) as key but it is not needed - only one key (Id) is enough
                    bBuilder.Property<Guid>("Id");
                    bBuilder.Property<Guid>("AId").HasColumnName("AId");
                    bBuilder.WithOwner().HasForeignKey("AId");

                    bBuilder.OwnsOne<C>(b => b.C, cBuilder =>
                    {
                        cBuilder.Property<Guid>("Id");
                        cBuilder.Property<Guid>("BId").HasColumnName("BId");
                        cBuilder.WithOwner().HasForeignKey("BId");
                    });
                }
            );
        });

Unable to create a 'DbContext' of type 'DatabaseContext'. The exception 'The keys {'BId'} on 'C' and {'Id'} on 'B' are both mapped to 'B.PK_B', but with different columns ({'BId'} and {'Id'}).' was thrown while attempting to create an instance.

6 Replies

Sehra•3d ago

how would a key on only B.Id work since you say OwnsMany

AdamOP•3d ago

class A
{
  private List<B> bList = [];

  public AddB(){
    bList.Add(new B(Guid.NewGuid()));
  }
}

class A
{
  private List<B> bList = [];

  public AddB(){
    bList.Add(new B(Guid.NewGuid()));
  }
}

A looks like this B.Id is always unique so it can be the only key afaik

Sehra•3d ago

class DB(DbContextOptions o) : DbContext(o)
{
  protected override void OnModelCreating(ModelBuilder m)
  {
    m.Entity<A>(a =>
    {
      a.OwnsMany<B>(
        x => x.Bs,
        b =>
        {
          b.HasKey(x => x.Id);
          b.OwnsOne(x => x.C);
        }
      );
    });
  }
}

class A
{
  public Guid Id { get; set; }
  public List<B> Bs { get; set; }
}

class B
{
  public Guid Id { get; set; }
  public A A { get; set; }
  public C C { get; set; }
}

class C
{
  public int Value { get; set; }
}

class DB(DbContextOptions o) : DbContext(o)
{
  protected override void OnModelCreating(ModelBuilder m)
  {
    m.Entity<A>(a =>
    {
      a.OwnsMany<B>(
        x => x.Bs,
        b =>
        {
          b.HasKey(x => x.Id);
          b.OwnsOne(x => x.C);
        }
      );
    });
  }
}

class A
{
  public Guid Id { get; set; }
  public List<B> Bs { get; set; }
}

class B
{
  public Guid Id { get; set; }
  public A A { get; set; }
  public C C { get; set; }
}

class C
{
  public int Value { get; set; }
}

CREATE TABLE "A" (
    "Id" uuid NOT NULL,
    CONSTRAINT "PK_A" PRIMARY KEY ("Id")
);
CREATE TABLE "B" (
    "Id" uuid NOT NULL,
    "AId" uuid NOT NULL,
    "C_Value" integer,
    CONSTRAINT "PK_B" PRIMARY KEY ("Id"),
    CONSTRAINT "FK_B_A_AId" FOREIGN KEY ("AId") REFERENCES "A" ("Id") ON DELETE CASCADE
);
CREATE INDEX "IX_B_AId" ON "B" ("AId");

CREATE TABLE "A" (
    "Id" uuid NOT NULL,
    CONSTRAINT "PK_A" PRIMARY KEY ("Id")
);
CREATE TABLE "B" (
    "Id" uuid NOT NULL,
    "AId" uuid NOT NULL,
    "C_Value" integer,
    CONSTRAINT "PK_B" PRIMARY KEY ("Id"),
    CONSTRAINT "FK_B_A_AId" FOREIGN KEY ("AId") REFERENCES "A" ("Id") ON DELETE CASCADE
);
CREATE INDEX "IX_B_AId" ON "B" ("AId");

AdamOP•3d ago

thanks

Sehra•3d ago

$close

MODiX•3d ago

If you have no further questions, please use /close to mark the forum thread as answered

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✅ [solved] efcore owned entity issue

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