How to convert RequestHeader to custom object in Spring

Question

I have method in my controller:

@RequestMapping(method = RequestMethod.POST)
public CustomObject createCustomObject(final @RequestHeader("userId") Long userId) {
   ...
}

Can I write some custom converter or something like that to convert this RequestHeader userId param to User object so my method will be:

@RequestMapping(method = RequestMethod.POST)
public CustomObject createCustomObject(final User user) {
   ...
}

Is it possible to do with spring-mvc?

Answer 1

Basically I implemented it with the suggestion from the comments. Below is an example:

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestHeader;

@RestController
public class SimpleController {

    @GetMapping("/user")
    public String greeting(@RequestHeader(name = "userId") User user) {
        return "Hey, " + user.toString();
    }
}

public class User {
    private String id;
    private String firstName;
    private String lastName;
    ...
}

And then we'll create a converter:

import org.springframework.core.convert.converter.Converter;
import org.springframework.stereotype.Component;

@Component
public class UserFromHeaderConverter implements Converter<String, User> {

    @Override
    public User convert(final String userId) {
        // fetch user from the database etc.
        
        final User user = new User();
        user.setId(userId);
        user.setFirstName("First");
        user.setLastName("Last");

        return user;
    }
}

To test it, please execute: curl --header "userId: 123" localhost:8080/user

Result would be: Hey, User{id='123', firstName='First', lastName='Last'}

Versions:

• spring-boot:2.0.3
• spring-web:5.0.7