How do I insert nested objects correctly in Ef

Question

I had a problem trying to add object from dto.

I have a DTO like this

  public class CustomerCourseSessionDto : IDto
  {
    public int Id { get; set; }
   
    public int? ConnectorId { get; set; } 
    public List<SomeObject>? SomeObject { get; set; }
    public List<OtherObject>? OtherObject { get; set; }
  }

and I'm trying to insert this DTO sent from the UI. I'm using a loop(foreach) for this, but it didn't feel right to me.

Maybe entityframework suggests a method for this, idk...

Other objects are like this

 public class SomeObject: IEntity
  {
    public int Id { get; set; }
    public int? ConnectorId { get; set; } 
  }

 public class OtherObject: IEntity
  {
    public int Id { get; set; }
    public int? ConnectorId { get; set; } 
  }

Thanks for the suggestions.

Here is where I use the loop:

    [TransactionScopeAspect]
        public IResult AddWithDto(CustomerCourseSessionDto courseSessionDto)
        {
    
          foreach (var item in courseSessionDto.Participants)
          {
            _someObjectService.Add(item);
          }
    
          foreach (var item in courseSessionDto.Lessons)
          {
            _otherObjectService.Add(item);
          }
    
          _customerCourseSessionDal.Add(new CustomerCourseSession
          {
            Id = courseSessionDto.Id,
            CustomerCourseId = courseSessionDto.CustomerCourseId,
          
          });
          return SuccessResult with message ;
        }

Can you please show the code that you're actually using? The one you mention in "I'm using a loop(foreach) for this". — Sergii Kudriavtsev
– Sergii Kudriavtsev, Commented Oct 25, 2022 at 14:11
Remove all this code and that TransactionScopeAspect. Just someContext.CourseSession.Add(sessionAndAll); is enough. That will add all related objects in the Added state. A DbContext is already a Unit-of-Work, so when SaveChanges is called all changes will be persisted in a single database transaction — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Oct 25, 2022 at 14:18
BTW there's no EF Core in the question. No DbContext. TransactionScopeAspect isn't an EF Core attribute nor would it matter. All pending changes are saved with SaveChanges. There are multiple "services" which means that either EF isn't used at all, or it's used incorrectly. At best those "services" are just wrappers over an injected DbContext — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Oct 25, 2022 at 14:19
This code is working well but is there any other way to do it without loop? — Uğur Han Atılgan
– Uğur Han Atılgan, Commented Oct 25, 2022 at 14:20

rjs123431 · Accepted Answer · 2022-10-25 16:58:27Z

1

You should design your entities to have a link to each table using foreign keys.

    public class CustomerCourseSession
    {
        public int Id { get; set; } // Primary Key
        public string Name { get; set; }
        public virtual ICollection<CourseParticipant> Participants { get; set; }
        public virtual ICollection<CourseLesson> Lessons { get; set; }
    }

    public class CourseParticipant
    {
        public int Id { get; set; }
        public int CustomerCourseSessionId { get; set; } // Foreign Key from CustomerCourseSession
        // other fields here
        
        public virtual CustomerCourseSession CustomerCourseSession { get; set;}
    }
    
    public class CourseLesson
    {
        public int Id { get; set; }
        public int CustomerCourseSessionId { get; set; } // Foreign Key from CustomerCourseSession
        // other fields here
        
        public virtual CustomerCourseSession CustomerCourseSession { get; set;}
        
    }

Then you can just call:

var entity = MapDtoToEntity(courseSessionDto);

_dbContext.CustomerCourseSessions.Add(entity);

_dbContext.SaveChanges();

answered Oct 25, 2022 at 16:58

rjs123431

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3 Comments

Uğur Han Atılgan Over a year ago

I changed my design like you say but it didn't work :S

rjs123431 Over a year ago

What do you mean it didn't work? can you post some of you code?

Uğur Han Atılgan Over a year ago

Of course I can , which part exactly ?

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