CODEWITHSUNDEEP
javajsonspringvalidation
User_007
User_007

Reputation: 165

Validate Json Object before casting it to POJO - using @requestBody

I would like to validate the incoming json object in controller before casting it to POJO using spring jackson.

My Controller:

@RequestMapping( value = "/createContact" , method = RequestMethod.POST , consumes = MediaType.APPLICATION_JSON_VALUE , produces = MediaType.APPLICATION_JSON_VALUE )
    public Contact createContact( @RequestBody Contact contact ) throws Exception
        {
            return ContactService.createContact( contact );
        }

My Contact.java

public class Contact
{

    private String ID = UUID.randomUUID().toString();

    private String type = "contact";

    private String category;

    private String name;
}

What I am trying to achieve is that 'type' field should not be passed in the request json. I need to throw an exception if the consumer passes that value.

I can get the json as a Map or string and validate it and then cast it to POJO. But is it possible to validate it before direct casting?

Upvotes: 0

Views: 1350

Answers (1)

Bunti
Bunti

Reputation: 1760

This can be done with an interceptor which will extend HandlerInterceptor. For example, you can create a ContactRequestValidator class like below.

@Component("contactRequestInterceptor")
public class ContactRequestValidator implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
      // get the request payload using reader from httpServletRequest and do the validation 
      // and throw an exception if not valid and may handle it using an Spring MVC exception handler 
    }

    // other two methods omitted..
}

Then register the validator interceptor with

@Configuration
public class MVCConfigurerAdapter extends WebMvcConfigurerAdapter {

    @Autowired
    @Qualifier("contactRequestInterceptor")
    private HandlerInterceptor contactRequestValidator;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        registry.addInterceptor(contactRequestValidator).addPathPatterns("/api/**"); // Also have the option to use Ant matchers
    }
}

Upvotes: 2

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