Circular references on .NET , Entity Framework and WebAPI

Imagine having a class Department( ID, Name) and Employee ( ID , Name, IDDepartment) . You want to return in the WebAPI the Departments with the Employee . It is simple to wrote this code:

[HttpGet]
public IEnumerable<Department> Get([FromServices] MyTestDatabaseContext context)
{
var departments = context.Department.Include(iterator=>iterator.Employee).ToArray();
return departments;
}

But the problem is with circular references when serializing  : The Department has a list of  Employees  that have a Department that have a list of Employees that …

 

 

Solution 1 :  Delete/Comment from the EF generated code what you do not need ( in this case , the Department reference that the Employee has)

public partial class Employee
{
public int Idemployee { get; set; }
public string NameEmployee { get; set; }
public int Iddepartment { get; set; }

//public Department IddepartmentNavigation { get; set; }
}

Solution 2 : Nullify the reference

[HttpGet]
public IEnumerable<Department> Get([FromServices] MyTestDatabaseContext context)
{
var departments = context.Department.Include(iterator=>iterator.Employee).ToArray();
foreach (var dep in departments)
{
foreach (var emp in dep.Employee)
{
emp.IddepartmentNavigation = null;
}
}
return departments;
}

( maybe this should be add to the partial class of the employee ?)

 

 

Solution 3: Handle circular references in serialization

services
.AddMvc()
.AddJsonOptions(opt =>
{
opt.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
opt.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore;
});

Solution 4: Make a read DDD design. Read https://siderite.dev/2018/08/client-models-vs-data-transfer-objects.html