How to convert String to list in java8 using ObjectMapper?

Question

I have a JSON String called primarySkillStr :

[
  {
    "id": 3,
    "roleIds": [
      2
    ],
    "rating": 2
  }

]

I try to map it to an object as follows:

primarySkillList = mapper.readValue(primarySkillStr, 
    new TypeReference<List<PrimarySkillDTO>>() {});

But when Iam converting this to a List then the roleIds List is null. Am I doing something wrong, or is there any other way?

This is my DTO

public class PrimarySkillDTO {
    private Integer id;
    private Integer rating;
    private List<Integer> roleIds;
    private String name;
}

I have the following annotations in the PrimarySkillDTO class

@Data
@Builder
@AllArgsConstructor
@JsonIgnoreProperties(ignoreUnknown = true)
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonNaming(PropertyNamingStrategy.SnakeCaseStrategy.class)

seems to work here: [PrimarySkillDTO(id=3, roleIds=[2], rating=2)] - how does your DTO look like? — Nick Vanderhoven, Feb 22 '17 at 11:15
How does java8 relate to this question at all? Isn't it just Jackson? — M. Prokhorov, Feb 22 '17 at 11:18
everything is private, what else do you have in the DTO? Do you have getters? — Nick Vanderhoven, Feb 22 '17 at 11:36
with your DTO + getters, the result is [PrimarySkillDTO(id=3, rating=2, roleIds=[2], name=null)] — Nick Vanderhoven, Feb 22 '17 at 11:37
it looks like something is wrong with the accessors, maybe the name of the getter or something? — Nick Vanderhoven, Feb 22 '17 at 11:37

score 5 · Answer 1 · answered Feb 22 '17 at 11:57

5

The problem is that your JsonNaming annotation requires snake_case and you are not using it.

To solve it

remove the annotation @JsonNaming(PropertyNamingStrategy.SnakeCaseStrategy.class)
or, rename the variable in the JSON String to role_ids

answered Feb 22 '17 at 11:57

Nick Vanderhoven

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OK.I got it.Thanks a lot – Supriya C S Feb 22 '17 at 12:38
Great! Feel free to accept the answer if it helped you out. – Nick Vanderhoven Feb 22 '17 at 12:45

score 3 · Answer 2 · answered Nov 21 '19 at 09:51

SnakeCaseStrategy will map roleIds <--> role_ids, The following codes work for me:

ObjectMapper objectMapper = new ObjectMapper();

TypeReference<List<TestClass>> typeRef = new TypeReference<List<TestClass>>() {};

List<TestClass> testList = objectMapper.readValue(testStringObject, typeRef);

How to convert String to list in java8 using ObjectMapper?

2 Answers2