Retrieving a response from a third party API and convert it to a new format [Spring Boot and Java]

[Geane Norm]

Hi,
I have a task whereby I need to integrate with a third party API. I am planning to do something along these lines: https://spring.io/guides/gs/consuming-rest/, meaning using Spring’s RestTemplate to retrieve the response of an external API from within my Spring Boot application. Until this all good, but the second step is to "re-construct" aka convert the existing response to a new format.

For example, the original response from the 3rd party API is something like:

[

{
        "field_1": {
            "field_1_1": "some stuff",
            "field_1_2": "other stuff"
        },
       "field_3": {
            "field_3_1": "stuff"
        },        
       "id": "5142372d-19bb-4e62-83c9-5ae428c88ae6",
       "field_4": "more more stuff"
    }
]

and the expected customised output should look like:

[
  {
    "field_1_1": "some stuff",
    "field_1_2": "other stuff",
    "field_3": [
      {
        "field_3_1": "stuff",
        "new_field": [
          {
            "application_id": "5142372d-19bb-4e62-83c9-5ae428c88ae6",
            "field_4": "more more stuff"
          }
        ]
      }
    ]
  }
]

Expected changes are both in format/data structure (e.g. field_3_1 is now a field inside an array) and the field naming convention (e.g: "id" becomes "application_id"). Is there any Spring library/class I can use for easily make the conversion? I will create a new model class with the customised response, but I am not sure about the approach for re-structuring the data. Can you help? Is there any example I can look it up?

Thank you,

G.

[Himai Minh]

You may need to use a Json parser such as JSONParser to parse your original Json object and collect the data.
Then, use your data to create a new Json object.


Reference:
https://www.geeksforgeeks.org/parse-json-java/

[Geane Norm]

Himai Minh wrote:You may need to use a Json parser such as JSONParser to parse your original Json object and collect the data.
Then, use your data to create a new Json object.


Reference:
https://www.geeksforgeeks.org/parse-json-java/

Hi,
thank you for your reply. So, as it stands, I can successfully consume the third party service for which I created a Dto with all expected @JsonProperty per field. I have also created an entity for the expected new format and its Dto. What is the best to go about? Can I convert the initial Dto with the new format one and in my Controller I will return the new format? Would you happen to have any example I can check?

Thank you,

[Himai Minh]

Yes. You may need to create a DTO to transform the object. And the return type is that DTO.