I use Entity Framework Core 2.0.1 and the goal is to insert some many-to-many related objects in the DB by an auxiliar entity. However, I get the error:
"The instance of entity type 'ReferenciaFabricanteTieneReferenciaConstructor' cannot be tracked because another instance with the key value 'IdReferenciaConstructor:0, IdReferenciaFabricante:0' is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached.".
I guess that the problem may be that in the list of join objects to be inserted, each of them have the foreign keys (ID's) as 0, but I thought EF would get rid of this generating the corresponding values for the entities ID's (if new), inserting/modifying them and finally the join one with these values updated.
What should I change in order to achieve this many-to-many insertion?
The classes are:
[Table("ReferenciasFabricante", Schema = "public")]
public class ReferenciaFabricante
{
[Key]
public int Id { get; set; }
...
//JOIN TABLE
public IList<ReferenciaFabricanteTieneReferenciaConstructor> ReferenciaFabricanteTieneReferenciaConstructor { get; set; }
}
[Table("ReferenciasConstructor", Schema = "public")]
public class ReferenciaConstructor
{
[Key]
public int Id { get; set; }
...
//JOIN TABLE
public IList<ReferenciaFabricanteTieneReferenciaConstructor> ReferenciaFabricanteTieneReferenciaConstructor { get; set; }
}
//JOIN TABLE
[Table("ReferenciaFabricanteTieneReferenciaConstructor", Schema = "public")]
public class ReferenciaFabricanteTieneReferenciaConstructor {
[Key]
public int IdReferenciaFabricante { get; set; }
public ReferenciaFabricante ReferenciaFabricante { get; set; }
[Key]
public int IdReferenciaConstructor { get; set; }
public ReferenciaConstructor ReferenciaConstructor { get; set; }
}
Model:
protected override void OnModelCreating(ModelBuilder modelBuilder) {
modelBuilder.Entity<ReferenciaFabricanteTieneReferenciaConstructor>().HasKey(v => new { v.IdReferenciaFabricante, v.IdReferenciaConstructor });
}
Code:
foreach (ApplicationCore.Entities.ReferenciaFabricanteTieneReferenciaConstructor referenciaFabricanteTieneReferenciaConstructor in referenciaConstructor.ReferenciaFabricanteTieneReferenciaConstructor) {
//ERROR
_dbContext.ReferenciaFabricanteTieneReferenciaConstructor.Add(referenciaFabricanteTieneReferenciaConstructor);
}
As GertArnold said, some properties were missing. Updated classes:
[Table("ReferenciasFabricante", Schema = "public")]
public class ReferenciaFabricante
{
[Key]
public int Id { get; set; }
...
//JOIN TABLE
[InverseProperty("ReferenciaFabricante")]
public IList<ReferenciaFabricanteTieneReferenciaConstructor> ReferenciaFabricanteTieneReferenciaConstructor { get; set; }
}
[Table("ReferenciasConstructor", Schema = "public")]
public class ReferenciaConstructor
{
[Key]
public int Id { get; set; }
...
//JOIN TABLE
[InverseProperty("ReferenciaConstructor")]
public IList<ReferenciaFabricanteTieneReferenciaConstructor> ReferenciaFabricanteTieneReferenciaConstructor { get; set; }
}
//JOIN TABLE
[Table("ReferenciaFabricanteTieneReferenciaConstructor", Schema = "public")]
public class ReferenciaFabricanteTieneReferenciaConstructor {
[Key]
public int IdReferenciaFabricante { get; set; }
[ForeignKey("IdReferenciaFabricante")]
public ReferenciaFabricante ReferenciaFabricante { get; set; }
[Key]
public int IdReferenciaConstructor { get; set; }
[ForeignKey("IdReferenciaConstructor")]
public ReferenciaConstructor ReferenciaConstructor { get; set; }
}