Using Retrofit to access JSON arrays

Question

I thought I understood how to do this, but obviously not. I have my API from Flickr, which begins like so:

jsonFlickrApi({    "photos":{       "page":1,       "pages":10,       "perpage":100,       "total":1000,       "photo":[          {             "id":"12567883725",             "owner":"74574845@N05",             "secret":"a7431762dd",             "server":"7458",             "farm":8,             "title":"",             "ispublic":1,             "isfriend":0,             "isfamily":0,             "url_l":"http:\/\/farm8.staticflickr.com\/7458\/12567883725_a7431762dd_b.jpg",             "height_l":"683",             "width_l":"1024"          } 

Now the information I need to get is from within the photo array, so what I have been trying to do is:

interface ArtService {      @GET("/services/rest/?method=flickr.photos.getRecent&extras=url_l&owner_name&format=json")     PhotosResponse getPhotos();      public class PhotosResponse {         Photos photos;     }      public class Photos {         List<Arraz> photo;     }      public class Arraz {         int id;         String title;         String owner;         String url_l;     } } 

Very clear that I seem to be missing the point, however I am unsure of how to get the information..

Answer 1

I would suggest using http://www.jsonschema2pojo.org. You can paste your JSON and it will generate the POJOs for you.

That should do the trick.

Answer 2

A quick look at Retrofit's docs says it uses Gson to convert JSON to Java classes. This means you need a class hierarchy in Java that matches the JSON. Yours ... doesn't.

The returned JSON is an object with a single field "photos" that holds an object;

{ "photos" : { ... } } 

So, your top level class would be a Java class with a single field:

public class PhotosResponse {     private Photos photos;      // getter/setter } 

And that Photos type would be another class that matches the JSON for the object that field contains:

{ "page":1, "pages":10, ... } 

So you'd have:

public class Photos {     private int page;     private int pages;     private int perpage'     private int total;     private List<Photo> photo;      // getters / setters } 

And then you'd create a Photo class to match the structure of the object in that inner array. Gson will then map the returned JSON appropriately.