I tried to serialize POCO class that was automatically generated from Entity Data Model .edmx and when I used
JsonConvert.SerializeObject
For not looping this worked for me-
ReferenceLoopHandling = ReferenceLoopHandling.Ignore,
I've solved it all here - Entity Framework children serialization with .Net Core 2 WebAPI https://gist.github.com/Kaidanov/f9ad0d79238494432f32b8407942c606
Will appreciate any remarks. maybe someone can use it sometime.