Entity Framework problem

Question

Hello

Below is my model

public class Room
{
public int Id { get; set; }

public string Name { get; set; }

public virtual Floor Floor { get; set; }

public int AcUnitId { get; set; }
public virtual AcUnit AcUnit { get; set; }
}

public class AcUnit
{

public int Id { get; set; }
[Required]
public string Name { get; set; }
public int RoomId { get; set; }

public virtual Room Room { get; set; }
}

Now when i try to assign object

room.AcUnit = room1.Acunit;

I got error "A primary key property that is a part of referential integrity constraint cannot be changed when the dependent object is Unchanged unless it is being set to the association's principal object. The principal object must be tracked and not marked for deletion"

Can anybody help to resolve this?

Suraj Sahoo · Answer

Ok Keyur. I got your problem Just tell me one thing is your Primary Key autoincremented>?? If yes then do the below: var room = new AcUnit(); room.(All the properties you need for AcUnit  except Id) like room.Name = room1.Name; room.OtherProperty = room1.Otherproperty but not the primary key. Else the conflict occurs as you are trying to violate the domians i.e. the uniqueness for the Primary key. 2nd condition: If primary key is not auto incremented. Assign a unque primary key. But usually this is bad approach. The primary key should be Identity column. you can update the Table at any moment though. I hope you understand from this the issue. Accept if this answer helps you anyway. Thanks

Pranay Rana · Answer

By doing this line in code room.AcUnit = room1.Acunit; you are actually confusing EF because you are trying to update full entity with its primary key value. To avoid this you just update property of the object except primary key rather than assigning full object. for this task you may use mapper to map values or you can do it delete existing AcUnit object and assign new one that you want.

keyur · Answer

Suraj I already tried to use new object assign each and also using FK this all are work.But I am coufuse as i already have object then why i can not use.

Suraj Sahoo · Answer

Did that work Keyur?

keyur · Answer

Hello Suraj Thanks for reply room1 is existing object from Room tables.So I fetch exist data and assign room1 acunit to new room. In which object I have to create Primary key? In room there is already PK is Id. Can you tell me more about this? Keyur

Suraj Sahoo · Answer

Hello keyur This problem is arising as you are assigning entire object to the same type. That is the primary key conflicts here as that needs to be unique. You are assigning the same object that to of same type. Can you please mention what is room1 ?? You first need to make the primary key an identity column(auto-incrementing) Then assign only the values except Primary key. Then it will create an object of type ACUnit with a unique next primary key. I hope you understand. Thanks