Map Nested JSON Objects to Java Classes with Spring RestTemplate

Question

I know this may be simple. However, I just can't get it to work.

So I am trying to use Spring RestTemplate to map my JSON data. I have following JSON response from a rest call.

{
  "message":"ok",
  "status":"ok",
  "data":[
      {"Name":"Yo",
       "Address":"100 Test Rd"},
      {...},
      {...}
   ]
}

And here is the class I am trying to map it to.

@JsonIgnoreProperties(ignoreUnknown = true)
public class Response implements Serializable {

  private String message;
  private String status;
  private List<Data> data;

  // I could also use a array instead
  // private Data[] data;
}

Here is my Data class:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Data implements Serializable {

  private String Name;
  private String Address;
}

Here is the code I used to call RestTemplate:

public Reponse getResponse() {
    ResponseEntity<Reponse> responseEntity = restTemplate.getForEntity(Url, Reponse.class);

    return responseEntity.getBody();
}

Now here comes the problem. I was able to get "message" and "status", But when I try to log/print data, it shows null. Not exactly sure what's going on here. I really could use some help. Thanks.

i'm having the same issue did you find a solution for this?

user2137817
– user2137817

2016-08-18 14:16:50 +00:00
Commented Aug 18, 2016 at 14:16 — user2137817
– user2137817, Commented Aug 18, 2016 at 14:16
DId you find any solution? thanks.

Fco
– Fco

2017-10-03 04:31:42 +00:00
Commented Oct 3, 2017 at 4:31 — Fco
– Fco, Commented Oct 3, 2017 at 4:31

O. Coburn · Accepted Answer · 2017-01-22 14:24:07Z

5

I was having a similar issue with RestTemplate not mapping nested JSON objects to my class model also, after much frustration I decided to retrieve my JSON as a String(instead of converting directly to my target object) using RestTemplate and then use the google Gson library to convert my String to my target entity.

pom.xml

<dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.2.4</version>
    </dependency>

code to call RestTemplate:

 ResponseEntity<String> responseEntity = restTemplate.getForEntity(Url,String.class);
Gson gson = new GsonBuilder().create();
Response reponse = gson.fromJson(responseEntity , Response.class);

Unfortunately I was unable to find out why my nested objects were not mapped using RestTemplate the first place but I hope this workaround helps!

answered Jan 22, 2017 at 14:24

O. Coburn

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1 Comment

Kay Over a year ago

I removed the nested class and created another class

Abhishek Tripathi · Accepted Answer · 2017-07-22 20:04:18Z

4

I had a similar issue when reading Json data from REST API using Rest Template. To resolve declare getters and setters for the List:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Response implements Serializable {

  private String message;
  private String status;
  private List<Data> data;

 // getters and Setters for the list. 


}

The RestTemplate will internally map the values from the listarray to the corresponding array.

answered Jul 22, 2017 at 20:04

Abhishek Tripathi

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Comments

James · Accepted Answer · 2018-02-28 22:13:45Z

2

I ran into the same issue. Annotate with @JsonProperty:

@JsonIgnoreProperties(ignoreUnknown = true)
public class Data implements Serializable {

    @JsonProperty("Name")
    private String name;

    @JsonProperty("Address")
    private String address;

    // getters / setters for name and address

}

The fields of your Data class should now get populated, and you can name your fields independent of the JSON representation (e.g. name instead of Name).

answered Feb 28, 2018 at 22:13

James

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Comments

isank-a · Accepted Answer · 2017-08-22 13:53:58Z

1

Annotate property "data" with @JsonUnwrapped as below

@JsonIgnoreProperties(ignoreUnknown = true)
public class Response implements Serializable {
    private String message;
    private String status;
    @JsonUnwrapped
    private List<Data> data;
}

answered Aug 22, 2017 at 13:53

isank-a

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Comments

Tharindu Rathnayake · Accepted Answer · 2019-04-11 13:29:32Z

1

I know this is an old thread.

But for anyone having the same problem, you can use MappingJackson2HttpMessageConverter for this purpose with Jackson.

Please refer the answer given in this thread.

answered Apr 11, 2019 at 13:29

Tharindu Rathnayake

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Comments

Xuân Cường · Accepted Answer · 2021-12-08 07:40:35Z

1

Change this

private String message; private String status; private List<Data> data;

To This

public String message; public String status; public List<Data> data;

That worked for me !

answered Dec 8, 2021 at 7:40

Xuân Cường

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Comments

sayan · Accepted Answer · 2015-03-06 08:38:22Z

0

Please use private List<Data> data = new AllarList<Data>( ); and please provide getters( ) and setters( ) methods in both the classes.

Put @JsonInclude(Include.NON_EMPTY) above Data class

Please add below dependencies under section at your main POM.xml file and do maven compile. Then I guess your issue will get resolved.

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-annotations</artifactId>
            <version>2.2.3</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
            <version>2.2.3</version>
        </dependency>

        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-joda</artifactId>
            <version>2.1.1</version>
        </dependency>

        <dependency>
            <groupId>org.codehaus.jackson</groupId>
            <artifactId>jackson-mapper-asl</artifactId>
            <version>1.8.8</version>
        </dependency>

edited Mar 6, 2015 at 8:38

answered Mar 6, 2015 at 7:08

sayan

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2 Comments

Ren Over a year ago

I didn't put up setters and getters here to avoid messes. Tried to initialize "data". Still returns null. Also compile error on "Include.NON_EMPTY", "Include cannot be resolved to a variable"? Thanks.

sayan Over a year ago

please import this : import com.fasterxml.jackson.annotation.JsonInclude;

Andrey · Accepted Answer · 2016-03-27 07:09:00Z

-1

If you need only print data, you can do this

RestTemplate restTemplate = new RestTemplate();
ResponseEntity<String> response = restTemplate.getForEntity(
    "your url",
    String.class);

System.out.println(response);

answered Mar 27, 2016 at 7:09

Andrey

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