How to update entity?

I had a question more detailed earlier which I had no answer, I will have the same question with a simpler way:

I have an EF database with foreign key to another table.

I would like to UPDATE an ENTITY. But I need to this like this and I’ll write the codes below:

1. Go to database and retrieve the Member by id, return EF Member object
2. Do some changes on the object OUTSIDE the EF Context
3. Send the MODIFED EF Member into a Save method
4. In BL layer save method uses the context and save changes.

1)

MemberManager currentMemberManager = new MemberManager();
Member NewMember = currentMemberManager.GetById(2);

2)

NewMember.FirstName = "NewFirstName";
NewMember.LanguageId = 1;

3)

currentMemberManager.Save(NewMember);

4)

public void Save2(Member newMember)
{
    using (var Context = new NoxonEntities())
    {
        Member existingMember = Context.Member.First(c => c.Id == newMember.Id);
        existingMember.FirstName = newMember.FirstName;
        existingMember.Language = Context.Language.First(c => c.Id == newMember.LanguageId);
        Context.SaveChanges();//In here I get the error below
    }
}

The changes to the database were committed successfully, but an error
occurred while updating the object context. The ObjectContext might be
in an inconsistent state. Inner exception message: A referential
integrity constraint violation occurred: The property values that
define the referential constraints are not consistent between
principal and dependent objects in the relationship.

Note: You may suggest to SEND a different class (Ex: public class
MyMember) that has all the necessary properties and totally separated
from EF. But this requires much work to get all EF object converting
into my separate classes. Am I right?

I am hoping there is a way to Detach the entity just long enough for me to modify it and save the values into database. (Also, I tried the Detach method which updates no rows at all)

I’ve been trying to solve this for hours now.

Please, help me to understand it better, I really need a solution. Thank you so much to anyone how has some ideas.

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Could you do something simple like detaching the entity, then attaching it to the context when you’re ready to save?

MemberManager currentMemberManager = new MemberManager();
Member NewMember = currentMemberManager.GetById(2);

The get:

public Member GetById(int id)
{ 
  var member = YourContext.Members.FirstOrDefault(m => m.id == id);
  YourContext.Detach(member);
  return member;
}

The save:

public void Save2(Member newMember)
        {
            using (var Context = new NoxonEntities())
            {
                Context.Attach(newMember);
                Context.ObjectStateManager.ChangeObjectState(newMember, EntityState.Modified);
                Context.SaveChanges();
            }
        }

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0