RestTemplate result cannot be deserialized-CodePudding

I am trying to consume an external API in Springboot, but I cannot figure out how to convert the resttemplate result to a list.

the sample JSON data

 "posts": [
    { "id": 1,
    "author": "Rylee Paul",
    "authorId": 9,
    "likes": 960,
    "popularity": 0.13,
    "reads": 50361,
    "tags": [ "tech", "health" ]
    },

Post entity class

private int id;
    private String author;
    private int authorId;
    private int likes;
    private double popularity;
    private long reads;

    @JsonFormat(with = JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY)
    private List<String> tags;

Service class

 ResponseEntity<Post []> responseEntity =restTemplate.getForEntity(url,Post[].class,tagName);
Post [] posts=responseEntity.getBody();

getForEntity() method throw the following exception

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize value of type `[Lcom.example.demo.data.Post;` from Object value (token `JsonToken.START_OBJECT`)

I have spent hours and hours debugging it and searching online, but I cannot solve it. Could someone help me out? I appreciate it!

CodePudding user response：

Your JSON packet is having posts array enclosed by some other objects. So your mapping object structure should be:

public class Posts {
 private List<Post> posts;
 // getters and setters

}

CodePudding user response：

The problem is that the JSON data is in the form of an object, but you are asking it to deserialize an array. One possible solution would be to create a wrapper class:

public class PostsResponse {
    private Post[] posts;

    public Post[] getPosts() {
        return posts;
    }
}

Accessed like this:

ResponseEntity<PostsResponse> responseEntity =
        restTemplate.getForEntity(url, PostsResponse.class, tagName);
PostsResponse responseBody = responseEntity.getBody();
if (responseBody != null) {
    Post[] posts = responseBody.getPosts();
}

CodePudding user response：

You can create a wrapper class for Post.java

public class Posts {

  private List<Post> posts;
  
 //getters and setters or Lombok
 
}

and try

ResponseEntity<Posts> responseEntity =restTemplate.getForEntity(url,Posts.class);