In Spring, when we call methods like Errors#rejectValue() (ValidationUtils methods), the underlying implementation of Errors will not only register the provided code, but also a number of additional codes. MessageCodesResolver (an interface) is responsible to build these message codes. By default DefaultMessageCodesResolver implementation is used. In following examples, we will understand the way these additional codes are created and will map them to error messages.
Examples
An Object to validate
package com.logicbig.example;
import java.math.BigDecimal;
import java.time.LocalDate;
public class Order {
private LocalDate orderDate;
private BigDecimal orderPrice;
.............
}
Validator implementation
package com.logicbig.example;
import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
import java.math.BigDecimal;
public class OrderValidator implements Validator {
@Override
public boolean supports(Class<?> clazz) {
return Order.class == clazz;
}
@Override
public void validate(Object target, Errors errors) {
ValidationUtils.rejectIfEmpty(errors, "orderDate", "date.empty",
"Date cannot be empty");
ValidationUtils.rejectIfEmpty(errors, "orderPrice", "price.empty",
"Price cannot be empty");
Order order = (Order) target;
if (order.getOrderPrice() != null &&
order.getOrderPrice().compareTo(BigDecimal.ZERO) <= 0) {
errors.rejectValue("orderPrice", "price.invalid", "Price must be greater than 0");
}
}
}
Performing validations
In following example, we are printing the all codes associated with each error object:
package com.logicbig.example;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.ValidationUtils;
import java.math.BigDecimal;
import java.util.Arrays;
@Configuration
public class SimpleValidationExample {
@Bean
OrderValidator validator() {
return new OrderValidator();
}
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext(SimpleValidationExample.class);
Order order = new Order();
order.setOrderPrice(BigDecimal.ZERO);
BeanPropertyBindingResult bindingResult =
new BeanPropertyBindingResult(order, Order.class.getName());
OrderValidator validator = context.getBean(OrderValidator.class);
ValidationUtils.invokeValidator(validator, order, bindingResult);
bindingResult.getAllErrors().forEach(e -> {
Arrays.stream(e.getCodes()).forEach(System.out::println);
});
}
}
Outputdate.empty.com.logicbig.example.Order.orderDate
date.empty.orderDate
date.empty.java.time.LocalDate
date.empty
price.invalid.com.logicbig.example.Order.orderPrice
price.invalid.orderPrice
price.invalid.java.math.BigDecimal
price.invalid
The additional codes are appended with a combination of fully qualified object/field names to our provided code (the ones we provided as the second argument of ValidationUtils.reject methods in our validator class). Check out doc for a detailed description of how different combination of these codes are generated.
We can map one of above codes (for each error) to the message strings in our resource file.
Customizing DefaultMessageCodesResolver
By default DefaultMessageCodesResolver uses Format.PREFIX_ERROR_CODE which appends the user provided code (for example, 'orderDate' in above code) at the beginning of the generated message codes. Let's change that to Format.POSTFIX_ERROR_CODE:
package com.logicbig.example;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.DefaultMessageCodesResolver;
import org.springframework.validation.ValidationUtils;
import java.math.BigDecimal;
import java.util.Arrays;
@Configuration
public class CustomizedCodesResolverExample {
@Bean
OrderValidator validator() {
return new OrderValidator();
}
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext(CustomizedCodesResolverExample.class);
Order order = new Order();
order.setOrderPrice(BigDecimal.ZERO);
BeanPropertyBindingResult bindingResult =
new BeanPropertyBindingResult(order, Order.class.getName());
DefaultMessageCodesResolver messageCodesResolver =
(DefaultMessageCodesResolver) bindingResult.getMessageCodesResolver();
messageCodesResolver.setMessageCodeFormatter(
DefaultMessageCodesResolver.Format.POSTFIX_ERROR_CODE);
OrderValidator validator = context.getBean(OrderValidator.class);
ValidationUtils.invokeValidator(validator, order, bindingResult);
bindingResult.getAllErrors().forEach(e -> {
Arrays.stream(e.getCodes()).forEach(System.out::println);
});
}
}
Outputcom.logicbig.example.Order.orderDate.date.empty
orderDate.date.empty
java.time.LocalDate.date.empty
date.empty
com.logicbig.example.Order.orderPrice.price.invalid
orderPrice.price.invalid
java.math.BigDecimal.price.invalid
price.invalid
Resolving codes to messages
Since all implementations of ApplicationContext implement ResourceLoader, we can use it to get resource messages:
package com.logicbig.example;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.DefaultMessageCodesResolver;
import org.springframework.validation.ValidationUtils;
import java.math.BigDecimal;
import java.util.Locale;
@Configuration
public class CodeToMessagesExample {
@Bean
OrderValidator validator() {
return new OrderValidator();
}
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext(CodeToMessagesExample.class);
Order order = new Order();
order.setOrderPrice(BigDecimal.ZERO);
BeanPropertyBindingResult bindingResult =
new BeanPropertyBindingResult(order, Order.class.getName());
DefaultMessageCodesResolver messageCodesResolver =
(DefaultMessageCodesResolver) bindingResult.getMessageCodesResolver();
messageCodesResolver.setMessageCodeFormatter(
DefaultMessageCodesResolver.Format.POSTFIX_ERROR_CODE);
OrderValidator validator = context.getBean(OrderValidator.class);
ValidationUtils.invokeValidator(validator, order, bindingResult);
bindingResult.getAllErrors()
.forEach(e -> System.out.println(context.getMessage(e, Locale.US)));
}
}
OutputDate cannot be empty
Price must be greater than 0
In above example, since we did not provide any resource bundles, the default error messages (which we provided as last argument of ValidationUtils.reject methods) were printed.
Let's provide a properties file containing codes to message mappings:
src/main/resources/ValidationMessages_en.propertiesorderDate.date.empty=Order Date must be non-empty.
orderPrice.price.empty=Order Price must be non-empty.
orderPrice.price.invalid=Order Price must be zero or less.
package com.logicbig.example;
import org.springframework.context.MessageSource;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.validation.BeanPropertyBindingResult;
import org.springframework.validation.DefaultMessageCodesResolver;
import org.springframework.validation.ValidationUtils;
import java.math.BigDecimal;
import java.util.Comparator;
import java.util.Locale;
@Configuration
public class ResourceBundleMessageExample {
@Bean
OrderValidator validator() {
return new OrderValidator();
}
@Bean
public MessageSource messageSource() {
ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
messageSource.setBasename("ValidationMessages");
return messageSource;
}
public static void main(String[] args) {
AnnotationConfigApplicationContext context =
new AnnotationConfigApplicationContext(ResourceBundleMessageExample.class);
Order order = new Order();
order.setOrderPrice(BigDecimal.ZERO);
BeanPropertyBindingResult bindingResult =
new BeanPropertyBindingResult(order, Order.class.getName());
DefaultMessageCodesResolver messageCodesResolver =
(DefaultMessageCodesResolver) bindingResult.getMessageCodesResolver();
messageCodesResolver.setMessageCodeFormatter(
DefaultMessageCodesResolver.Format.POSTFIX_ERROR_CODE);
OrderValidator validator = context.getBean(OrderValidator.class);
ValidationUtils.invokeValidator(validator, order, bindingResult);
bindingResult.getAllErrors()
.stream()
.map(e -> context.getMessage(e, Locale.US))
.sorted(Comparator.naturalOrder())
.forEach(System.err::println);
}
}
OutputOrder Date must be non-empty.
Order Price must be zero or less.
Example ProjectDependencies and Technologies Used: - spring-context 6.1.2 (Spring Context)
Version Compatibility: 3.2.3.RELEASE - 6.1.2 Version compatibilities of spring-context with this example: Versions in green have been tested.
- JDK 17
- Maven 3.8.1
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