Resolving JSON deserialization error in Jira API

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1

Hey everyone! I’m working on a Jira API consumer and I’m stuck with a weird error. My code throws “Can not deserialize instance of Jira out of START_ARRAY token” when I try to parse the JSON response.

The JSON I’m getting looks like this:

[
  {
    "projectId": "1234",
    "projectName": "Sample Project",
    "projectKey": "SP",
    "projectType": "software",
    "avatarInfo": {
      "small": "url1",
      "medium": "url2",
      "large": "url3"
    }
  },
  {
    "projectId": "5678",
    "projectName": "Another Project",
    "projectKey": "AP",
    "projectType": "business"
  }
]

I’ve set up my Java classes like this:

class ProjectDetails {
    private String projectId;
    private String projectName;
    private String projectKey;
    private String projectType;
    private AvatarInfo avatarInfo;
    // getters and setters
}

class AvatarInfo {
    private String small;
    private String medium;
    private String large;
    // getters and setters
}

class JiraResponse {
    private List<ProjectDetails> projects;
    // getter and setter
}

I’m using RestTemplate to make the API call. Any ideas on how to fix this? I’m pretty new to working with APIs so I might be missing something obvious. Thanks for any help!

2

As someone who’s dealt with similar Jira API issues, I can tell you that the problem lies in how you’re trying to deserialize the JSON response. The API is returning an array of project objects, not a single object containing a list.

To fix this, you need to adjust your deserialization approach. Instead of using a JiraResponse class, you should directly deserialize into a List. Here’s a snippet that should work:

ObjectMapper mapper = new ObjectMapper();
List<ProjectDetails> projects = mapper.readValue(jsonString, new TypeReference<List<ProjectDetails>>(){});

This approach tells Jackson (assuming you’re using it) to parse the JSON array directly into a list of ProjectDetails objects. Make sure your ProjectDetails class matches the JSON structure exactly, including handling optional fields like avatarInfo.

Also, don’t forget to handle potential exceptions, as API responses can sometimes be unpredictable. Hope this helps solve your issue!

3

The error you’re encountering is due to a mismatch between your JSON structure and your Java classes. The API is returning an array of projects directly, not wrapped in a JiraResponse object.

To fix this, you need to adjust your deserialization approach. Instead of using a JiraResponse class, you should deserialize directly into a List. Here’s how you can modify your RestTemplate call:

ResponseEntity<List<ProjectDetails>> response = restTemplate.exchange(
    url,
    HttpMethod.GET,
    null,
    new ParameterizedTypeReference<List<ProjectDetails>>() {}
);
List<ProjectDetails> projects = response.getBody();

This change should resolve the deserialization error. Remember to ensure your ProjectDetails class matches the JSON structure exactly, including proper naming of fields and handling of optional fields like avatarInfo.

If you’re still having issues, double-check your JSON parsing library configuration and make sure it’s set up correctly for your project.

4

yo ive run into this before. its a pain in the butt! the json is an array, not an object. try this:

List projects = objectMapper.readValue(jsonString, new TypeReference<List>() {});

that should do the trick. if not, double check ur ProjectDetails class matches the json structure exactly. good luck!