A circular reference has been detected when serializing the object of class

A Circular Reference Exception

In object-oriented programming languages, a circular reference occurs when two or more objects reference each other, creating a loop that cannot be resolved. When attempting to serialize (convert to a data format such as JSON or XML) an object that contains a circular reference, a circular reference exception is thrown.

Let’s consider an example to understand this better. Suppose we have two classes, “Person” and “Home”, where a person can have a reference to their home, and a home can have a reference to its owner (a person). Here’s the code:

    public class Person
    {
        public string Name { get; set; }
        public Home Home { get; set; }
    }

    public class Home
    {
        public string Address { get; set; }
        public Person Owner { get; set; }
    }
  

In this example, both classes have a reference property to each other. If we try to serialize an instance of the “Person” class, it will also attempt to serialize the referenced “Home” object, which in turn will try to serialize the referenced “Person” object again. This creates an infinite loop, resulting in a circular reference exception.

To overcome this issue, we can use serialization attributes to control the serialization process. For example, we can use the [JsonIgnore] attribute from the Newtonsoft.Json library to ignore the circular reference property during serialization:

    public class Person
    {
        public string Name { get; set; }
        
        [JsonIgnore]
        public Home Home { get; set; }
    }

    public class Home
    {
        public string Address { get; set; }
        public Person Owner { get; set; }
    }
  

By adding [JsonIgnore] to the “Home” property in the “Person” class, we instruct the serializer to skip this property during serialization. Now, when serializing an instance of the “Person” class, the circular reference exception will not occur because the circular reference to the “Home” object is ignored.

Keep in mind that this is just one way to handle circular references during serialization. There are different approaches and libraries available depending on the programming language and serialization framework being used.