Partial fields update REST API

Question

There is this MongoBean: SuperBean

class SuperBean extends MongoBaseBean{
     private String id;
     private String title;
     private String parent;

     //And getters, setters   
}

Need is to write an update API, which is capable of performing partial attributes update. Common approach seen across the web as well as heard from my peers is to check the fields in the request for Null and update if not null. But what if the update request is for the value to be updated to Null??

After few discussions, we came up with three approaches:

• Set default value for the field in the bean. Hence instead of non-null parent field, if it does not have $ in the request, this will be considered for update.

  class SuperBean extends MongoBaseBean{
   private String id;
   private String title;
   private String parent = "$";
  
   //And getters, setters   
  }
  

• Let the update API Implementation accept a Map. The actual bean is fetched and all the fields that are present in the request map will be updated.

  @Post
  public SuperBean updatePartial(Map<String,Object> dataObject) {}
  

• Let the update API accept DTO, that contains 2 maps. One to contain old values, other for new values. This could be advantageous in scenarios, where the update has to happen only if the database contains the values as sent in oldDataObj. But this increases the payload size.

    class SuperBeanUpdateDTO {
       private Map<String, Object> oldDataObj;
       private Map<String, Object> newDataObject;
       //getters, setters
    }
  
    @Post
    public SuperBean updatePartial(SuperBeanUpdateDTO updateDTO) {}
  

What factors should be considered to chose one of these approaches? Is there another better way to approach this problem?

Answer 1

In my projects, we usually choose the way that similar with your second way. but not exactly the same.

for example, in your client side, you have a page or a view to modify your profile info, includes name, birthday, gender, although you just modify the name value, when you click save button, it still will send the data to server includes birthday and gender with name field, but just keep its value as old. and the server API will directly update these three values in database, won't check whether its value changed or not.

if you have another page or view to modify other parts of the profile, likes password, it need add a new method in client and a new API in server. the API URL likes PATCH /reset_password, and the sent data should include old_password and new_password field.

PS:
1. we use PUT or PATCH to update a resource, not POST, POST is used to create a new resource. 2. when you update a resource, in the above example, the API likes PATCH /profiles/:id (other's profile) or PATCH /profile (yourself profile), so the sent data doesn't need id field anymore, it includes in your API URL.