How to solve "Failed to convert property value[...]" - spring

Question

So I have a form with a dropdown in Spring MVC:
<form:form modelAttribute="user" action="registerVerify" method="post">
<!-- Other fields-->
<spring:message code="register.country" />
<form:select path="country" items="${countryList}" />
<br/>
</form:form>
Which is populated by this controller:
#Controller
public class RegisterController {
#RequestMapping(value = "registerForm", method = RequestMethod.GET)
public String register(#ModelAttribute("user") User user, Model model) {
model.addAttribute("user", new User());
model.addAttribute("countryList", cDao.getCountryMap());
model.addAttribute("companyList", cpDao.getCompanyMap());
return "login/registerForm";
}
#RequestMapping(value = "registerVerify", method = RequestMethod.POST)
public String makeRegistration(#ModelAttribute("user") #Valid User user, BindingResult result,
RedirectAttributes redirectAttributes, Model model) {
if (result.hasErrors()) {
System.out.println(result.getFieldError().getDefaultMessage());
model.addAttribute("org.springframework.validation.BindingResult.user", result);
return "redirect:registerForm";
}
if (dao.add(user)) {
redirectAttributes.addFlashAttribute("user", user);
return "redirect:login";
} else {
return "redirect:registerForm";
}
}
// Service classes bellow
I've made some converters
package br.com.sirious.energyquality.converters;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.convert.converter.Converter;
import br.com.sirious.energyquality.dao.CompanyDao;
import br.com.sirious.energyquality.models.Company;
public class IdToCompanyConverter implements Converter<String, Company>{
#Autowired
CompanyDao dao;
#Override
public Company convert(String id) {
return dao.getCompanyByID(Integer.parseInt(id));
}
}
And I've set My WebMVCConfig (and WebApplicationInitializer, and spring-context...)
#EnableWebMvc
#Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
#Override
public void addFormatters(FormatterRegistry registry){
registry.addConverter(new IdToCompanyConverter());
}
}
But I still get "Failed to convert property value of type [java.lang.String] to required type [br.com.sirious.energyquality.models.Company] for property 'Company'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [br.com.sirious.energyquality.models.Company] for property 'Company': no matching editors or conversion strategy found"
I've checked on many similar posts but none solved the problem. Can someone diagnose what is happening?

Answer 1

Try using the following ConverterRegistry method:
<S,T> void addConverter(Class<S> sourceType,
Class<T> targetType,
Converter<? super S,? extends T> converter)
Which will result in:
public void addFormatters(FormatterRegistry registry){
registry.addConverter(String.class, Company.class, new IdToCompanyConverter());
}

Answer 2

The problem lies on the path of the form:select tag:
<spring:message code="register.country" />
<form:select path="country" items="${countryList}" />
In order to map to the object that is used as reference, the path has to be the id of the object, so path will be: Country.id.
The idea is similar to what is said here: Spring form binding how to do it ? Cannot convert value of type [java.lang.String] to required type
Also, xuesheng has added some interesting information about registering the converter without using web.xml.