How to get around the Circular Reference issue with JSON and Entity
- by DanScan
I have been experimenting with creating a website that leverages MVC with JSON for my presentation layer and Entity framework for data model/database. My Issue comes into play with serializing my Model objects into JSON.
I am using the code first method to create my database. When doing the code first method a one to many relationship (parent/child) requires the child to have a reference back to the parent. (Example code my be a typo but you get the picture)
class parent
{
public List<child> Children{get;set;}
public int Id{get;set;}
}
class child
{
public int ParentId{get;set;}
[ForeignKey("ParentId")]
public parent MyParent{get;set;}
public string name{get;set;}
}
When returning a "parent" object via a JsonResult a circular reference error is thrown because "child" has a property of class parent.
I have tried the ScriptIgnore attribute but I lose the ability to look at the child objects. I will need to display information in a parent child view at some point.
I have tried to make base classes for both parent and child that do not have a circular reference. Unfortunately when I attempt to send the baseParent and baseChild these are read by the JSON Parser as their derived classes (I am pretty sure this concept is escaping me).
Base.baseParent basep = (Base.baseParent)parent;
return Json(basep, JsonRequestBehavior.AllowGet);
The one solution I have come up with is to create "View" Models. I create simple versions of the database models that do not include the reference to the parent class. These view models each have method to return the Database Version and a constructor that takes the database model as a parameter (viewmodel.name = databasemodel.name). This method seems forced although it works.
NOTE:I am posting here because I think this is more discussion worthy. I could leverage a different design pattern to over come this issue or it could be as simple as using a different attribute on my model. In my searching I have not seen a good method to overcome this problem.
My end goal would be to have a nice MVC application that heavily leverages JSON for communicating with the server and displaying data. While maintaining a consistant model across layers (or as best as I can come up with).
