Spring Boot Jackson - Selectively serialize embedded object properties based on their depth - json

Question

I have edited the question to provide more clarity.
My problem statement is how can I customize the way Jackson serializes an Entity that's sent in my REST Response, such that my JSON doesn't become too large / unreadable?
Consider I have the following Entities (or resources / models, etc)
public class Department
{
private Long id;
private String name;
private Employee head;
/***
* Other fields, getters and setters
*/
}
And another one, like this
public class Employee {
private Long id;
private String name;
private Department department;
/***
* Other fields, getters and setters
*/
}
I have a REST API that gets an Employee by his/her ID, and here's the response when I call that
GET /api/employees/2
{
"id":"2",
"name":"John Doe",
"department":{
"id":3,
"name":"Product Support",
"head":{
"id":1,
"name":"The Chairman",
"department":{
"id":1,
"name":"Executive",
"head":null
}
}
}
}
The response, as you can see, is large (and can get really large depending on the data model). I want to stop the serialization from going deep into nested objects.
My preferrable JSON Response would be:
GET /api/employees/2
{
"id":"2",
"name":"John Doe",
"department":{
"id":3,
"name":"Product Support",
}
}
I already am aware that I can use the #JsonIgnore annotation on Department.head, like this:
public class Department
{
private Long id;
private String name;
#JsonIgnore
private Employee head;
/***
* Other fields, getters and setters
*/
}
But, this will skip serializing the head property permanently. For instance, see the below REST API call, post adding #JsonIgnore
GET /api/departments/3
{
"id":3,
"name":"Product Support",
}
// Here, I want the Full serialized form of the Department Object
So, as you can see, here's the question: I want the Department object to be serialized fully, when I call GET /api/departments/3. But, I want it to skip the head property when I call GET /api/employees/2. How do I achieve this in Jackson, when used in Spring Boot?
I also came across a library called Squiggly that uses a GraphQL like query language for the API responses, but I would like to know if I can do without having to learn a new library.
Thanks very much
Edit After Abbin Varghese's Answer
I changed my Employee model to the one below:
public class Employee {
private Long id;
private String name;
#JsonIgnoreProperties({"head"})
private Department department;
/***
* Other fields, getters and setters
*/
}
Upon serialization, this gave me the following JSON output:
{
"id":"2",
"name":"John Doe",
"department":{
"id":3,
"name":"Product Support",
}
}
The pro here, is that it solves my problem, without having to write a separate DTO class for my models.
The con however, is this: In this case, I'm trying to skip serialization only for the head property, so it makes sense to include this in the #JsonIgnoreProperties annotation. What if the list of properties to skip is longer than the list of properties to serialize? For example, if my Department as 15 properties, and I wish to serialize only 3 of them, then it becomes difficult to include the 12 properties to skip in the #JsonIgnoreProperties annotation.
Is there an annotation that does the opposite (Include only these fields, etc.)??

Answer 1

JsonProperty.Access.WRITE_ONLY is a good way to avoid elements.
For example..
#JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
#ManyToOne
#JoinColumn(name = "MODIFIED_BY")
private User lastUpdatedBy;