Entity Framework Core Explicit Loading how to ignore deeper nested entities - nested

Question

I have a database with the following tables:
User:
public class User
{
public string UserId { get; set; }
public string Name { get; set; }
public Department DefaultDepartment { get; set; }
public ICollection<RoleDepartment> RoleDepartment{ get; set; }
}
Role:
public class Role
{
public int Id { get; set; }
public string Permissions { get; set; }
public ICollection<RoleDepartment> RoleDepartment{ get; set; }
}
RoleDepartment:
public class RoleDepartment
{
public int DepartmentId { get; set; }
public string UserId { get; set; }
public int RoleId { get; set; }
public Department Department { get; set; }
public User User { get; set; }
public Role Role { get; set; }
}
Department
public class Department
{
public int Id { get; set; }
public string Name { get; set; }
public ICollection<RoleDepartment> RoleDepartment { get; set; }
}
when i get user data as follow
User user = dbContext.Users
.Single(u => u.UserId == user_id);
dbContext.Entry(user).Reference(u => u.DefaultDepartment).Load();
dbContext.Entry(user).Collection(u => u.RoleDepartment).Load();
I receive too much data
{
"UserId": "***",
"Name": "***",
"DefaultDepartment": {
"Id": "**",
"Name": "***",
"RoleDepartment": [
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**",
"User": {
"UserId": "***",
"Name": "***",
"RoleDepartment": [
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**"
}
]
}
}
]
},
"RoleDepartment": [
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**",
"User": {
"UserId": "***",
"Name": "***",
"DefaultDepartment": {
"Id": "**",
"Name": "***",
"RoleDepartment": [
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**"
}
]
}
}
},
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**",
"Department": {
"Id": "**",
"Name": "***",
"RoleDepartment": []
},
"User": {
"UserId": "***",
"Name": "***",
"DefaultDepartment": {
"Id": "**",
"Name": "***",
"RoleDepartment": []
}
}
}
]
}
I want something like this:
{
"UserId": "***",
"Name": "***",
"DefaultDepartment": {
"Id": "**",
"Name": "***",
"RoleDepartment": [
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**"
}
]
},
"RoleDepartment": [
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**",
},
{
"DepartmentId": "**",
"UserId": "***",
"RoleId": "**"
}
]
}
There is a way to ignore the nested User and Department entities?
I want to ignore auto-loaded data when I use explicit-loading.
Did I miss something?
Thanks

Answer 1

This seems like a self referencing loop. If you are not using NewtonsoftJson install it using,
Install-Package Microsoft.AspNetCore.Mvc.NewtonsoftJson
You can then edit your startup.cs where you add in Newtonsoft to configure the ReferenceLoopHandling
public void ConfigureServices(IServiceCollection services)
{
services.AddControllers().AddNewtonsoftJson(x => x.SerializerSettings.ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore);
}
There is another way to avoid reference loops and that is to tell the serializer to not serialize a property at all. In both Newtonsoft.Json and System.Text.Json there is an attribute called JsonIgnore,
public class RoleDepartment
{
public int DepartmentId { get; set; }
public string UserId { get; set; }
public int RoleId { get; set; }
public Department Department { get; set; }
[JsonIgnore]
public User User { get; set; }
public Role Role { get; set; }
}
But the recomended way is to create DTOs/ViewModels and map your Entities with them. Refer this for more info.
Edit:
You can stop reference loops for this case only as follows.
User user = dbContext.Users
.Single(u => u.UserId == user_id);
dbContext.Entry(user).Reference(u => u.DefaultDepartment).Load();
dbContext.Entry(user).Collection(u => u.RoleDepartment).Load();
var Settings = new Newtonsoft.Json.JsonSerializerSettings
{
ReferenceLoopHandling = Newtonsoft.Json.ReferenceLoopHandling.Ignore
};
var TheJSON = Newtonsoft.Json.JsonConvert.SerializeObject(user, user.GetType().BaseType, Settings);
Also you can create an anonymous object as follows and return it as well.
dbContext.Users.Select(x => new { Prop1 = x.Property1, Prop2 = x.Property2 });