How to Get List of Objects via Requestbody in Spring

There are three ways to receive list or array of objects via @RequestBody annotation.

1. Use List with @RequestBody

Suppose we have an entity class named UserCreateForm, it is used to hold user information which is necessary for creating a new user.

//form class for creating user
@Data
@NoArgsConstructor
@AllArgsConstructor
public class UserCreateForm {
    private String name;
    private Integer age;
}

// controller method
 @PostMapping("/users")
    public void batchCreateUser(@RequestBody List<UserCreateForm> forms) {
        log.info("request: {}", forms);
    }

If you call api with below data:

POST http://localhost:8080/list-via-request-body/users/1
Content-Type: application/json

[
  {
    "name": "Jone",
    "age": 21
  },
  {
    "name": "Jessica",
    "age": 20
  }
]

the output should be:

user: UserCreateForm(name=Jone, age=21)
user: UserCreateForm(name=Jessica, age=20)

2. Use array with @RequestBody

@PostMapping(value = "/users")
public @ResponseBody List<User> batchCreate(@RequestBody UserCreateForm[] forms) {
  log.info("array of users: {}", forms);
  return userService.create(forms);
}

THe input and output shoule be the same with the situation when you are using List.

3. Use a wrapper class

When you are working on an older version of spring or spring boot, the previous ways might not work at all, in that case a quick workaround is to have a wrapper class.

// User class

@Data
@NoArgsConstructor
@AllArgsConstructor
public class UserCreateForm {
    private String name;
    private Integer age;
}

// Wrapper class for User
@Data
@NoArgsConstructor
@AllArgsConstructor
public class UserWrapperForm {
    List<UserCreateForm> users;
}


// Controller class
@PostMapping(value = "/users")
public @ResponseBody List<User> batchCreate(@RequestBody UserWrapperForm form) {
  return userService.create(form);
}

the request turned out to be this:

POST http://localhost:8080/list-via-request-body/users/3
Content-Type: application/json

{
  "users": [
    {
      "name": "Jone",
      "age": 21
    },
    {
      "name": "Jessica",
      "age": 20
    }
  ]
}