Entity model:
public class DocumentType : CodeBase
{
[Required]
[MaxLength(100)]
public string Name { get; set; }
public TimeSpan? Productiontime { get; set; }
public bool IsDeliverable { get; set; }
public virtual ICollection<DocumentTypeRetractRelation> DocumentTypes { get; set; }
public virtual ICollection<DocumentTypeRetractRelation> RetractDocumentTypes { get; set; }
}
Relation model:
/// <summary>
/// Relationship between document types showing which documenttypes can
/// retracted when delivering a new document.
/// </summary>
[Table("DocumentTypeRetractRelation")]
public class DocumentTypeRetractRelation
{
public int DocumentTypeId { get; set; }
public virtual DocumentType DocumentType { get; set; }
public int RetractDocumentTypeId { get; set; }
public virtual DocumentType RetractDocumentType { get; set; }
}
Model builder:
modelBuilder.Entity<DocumentTypeRetractRelation>().HasKey(x => new { x.DocumentTypeId, x.RetractDocumentTypeId });
modelBuilder.Entity<DocumentTypeRetractRelation>()
.HasOne(x => x.DocumentType)
.WithMany(x => x.DocumentTypes)
.HasForeignKey(x => x.DocumentTypeId);
modelBuilder.Entity<DocumentTypeRetractRelation>()
.HasOne(x => x.RetractDocumentType)
.WithMany(x => x.RetractDocumentTypes)
.HasForeignKey(x => x.RetractDocumentTypeId);
Update writer:
public async Task<DocumentType> UpdateAsync(DocumentTypeUpdateDto documentTypeUpdateDto)
{
using (IUnitOfWork uow = UowProvider.CreateUnitOfWork<EntityContext>())
{
var documentTypeRepo = uow.GetCustomRepository<IDocumentTypeRepository>();
var existingDocument = await documentTypeRepo.GetAsync(documentTypeUpdateDto.Id);
if (existingDocument == null)
throw new EntityNotFoundException("DocumentType", existingDocument.Id);
foreach (var retractDocumentTypeId in documentTypeUpdateDto.RetractDocumentTypeIds)
{
existingDocument.RetractDocumentTypes.Add(new DocumentTypeRetractRelation()
{
DocumentTypeId = existingDocument.Id,
RetractDocumentTypeId = retractDocumentTypeId
});
}
documentTypeRepo.Update(existingDocument);
await uow.SaveChangesAsync();
return existingDocument;
}
}
When trying to update the existingDocument I get the following error:
The instance of entity type 'DocumentTypeRetractRelation' cannot be tracked because another instance of this type with the same key is already being tracked. When adding new entities, for most key types a unique temporary key value will be created if no key is set (i.e. if the key property is assigned the default value for its type). If you are explicitly setting key values for new entities, ensure they do not collide with existing entities or temporary values generated for other new entities. When attaching existing entities, ensure that only one entity instance with a given key value is attached to the context.
The problem is not the self referencing, but applying the many-to-many collection modifications which generate different DocumentTypeRetractRelation
objects with the same PK as stated in the exception message.
The correct way currently in EF Core is to make sure RetractDocumentTypes
of the existingDocument
are loaded (contains the original values), then merge the changes by either using an existing or create new DocumentTypeRetractRelation
objects.
Replace the following code
foreach (var retractDocumentTypeId in documentTypeUpdateDto.RetractDocumentTypeIds)
{
existingDocument.RetractDocumentTypes.Add(new DocumentTypeRetractRelation()
{
DocumentTypeId = existingDocument.Id,
RetractDocumentTypeId = retractDocumentTypeId
});
}
with
// existingDocument.RetractDocumentTypes should be loaded (either eager or explicit)
existingDocument.RetractDocumentTypes = (
from retractDocumentTypeId in documentTypeUpdateDto.RetractDocumentTypeIds
join existingRelation in existingDocument.RetractDocumentTypes
on retractDocumentTypeId equals existingRelation.RetractDocumentTypeId
into existingRelations
select existingRelations.FirstOrDefault() ?? new DocumentTypeRetractRelation()
{
DocumentTypeId = existingDocument.Id,
RetractDocumentTypeId = retractDocumentTypeId
}).ToList();
This would handle both added, removed and unchanged relations. You can do similar to DocumentTypes
.
Actually looking at your model, the above code should be for DocumentTypes
collection (since you a receiving the RetractDocumentTypeIds
, which in combination with the document Id
form the DocumentTypes
collection content). So simply replace the RetractDocumentTypes
with DocumentTypes
.