Cross field validation with Hibernate Validator (JSR 303)

Question

Is there an implementation of (or third-party implementation for) cross field validation in Hibernate Validator 4.x? If not, what is the cleanest way to implement a cross fi

Answer 1

I suggest you another possible solution. Perhaps less elegant, but easier!

public class MyBean {
  @Size(min=6, max=50)
  private String pass;

  private String passVerify;

  @AssertTrue(message="passVerify field should be equal than pass field")
  private boolean isValid() {
    return this.pass.equals(this.passVerify);
  }
}

The isValid method is invoked by the validator automatically.

Answer 2

Why not try Oval: http://oval.sourceforge.net/

I looks like it supports OGNL so maybe you could do it by a more natural

@Assert(expr = "_value ==_this.pass").

Answer 3

Cross fields validations can be done by creating custom constraints.

Example:- Compare password and confirmPassword fields of User instance.

CompareStrings

@Target({TYPE})
@Retention(RUNTIME)
@Constraint(validatedBy=CompareStringsValidator.class)
@Documented
public @interface CompareStrings {
    String[] propertyNames();
    StringComparisonMode matchMode() default EQUAL;
    boolean allowNull() default false;
    String message() default "";
    Class<?>[] groups() default {};
    Class<? extends Payload>[] payload() default {};
}

StringComparisonMode

public enum StringComparisonMode {
    EQUAL, EQUAL_IGNORE_CASE, NOT_EQUAL, NOT_EQUAL_IGNORE_CASE
}

CompareStringsValidator

public class CompareStringsValidator implements ConstraintValidator<CompareStrings, Object> {

    private String[] propertyNames;
    private StringComparisonMode comparisonMode;
    private boolean allowNull;

    @Override
    public void initialize(CompareStrings constraintAnnotation) {
        this.propertyNames = constraintAnnotation.propertyNames();
        this.comparisonMode = constraintAnnotation.matchMode();
        this.allowNull = constraintAnnotation.allowNull();
    }

    @Override
    public boolean isValid(Object target, ConstraintValidatorContext context) {
        boolean isValid = true;
        List<String> propertyValues = new ArrayList<String> (propertyNames.length);
        for(int i=0; i<propertyNames.length; i++) {
            String propertyValue = ConstraintValidatorHelper.getPropertyValue(String.class, propertyNames[i], target);
            if(propertyValue == null) {
                if(!allowNull) {
                    isValid = false;
                    break;
                }
            } else {
                propertyValues.add(propertyValue);
            }
        }

        if(isValid) {
            isValid = ConstraintValidatorHelper.isValid(propertyValues, comparisonMode);
        }

        if (!isValid) {
          /*
           * if custom message was provided, don't touch it, otherwise build the
           * default message
           */
          String message = context.getDefaultConstraintMessageTemplate();
          message = (message.isEmpty()) ?  ConstraintValidatorHelper.resolveMessage(propertyNames, comparisonMode) : message;

          context.disableDefaultConstraintViolation();
          ConstraintViolationBuilder violationBuilder = context.buildConstraintViolationWithTemplate(message);
          for (String propertyName : propertyNames) {
            NodeBuilderDefinedContext nbdc = violationBuilder.addNode(propertyName);
            nbdc.addConstraintViolation();
          }
        }    

        return isValid;
    }
}

ConstraintValidatorHelper

public abstract class ConstraintValidatorHelper {

public static <T> T getPropertyValue(Class<T> requiredType, String propertyName, Object instance) {
        if(requiredType == null) {
            throw new IllegalArgumentException("Invalid argument. requiredType must NOT be null!");
        }
        if(propertyName == null) {
            throw new IllegalArgumentException("Invalid argument. PropertyName must NOT be null!");
        }
        if(instance == null) {
            throw new IllegalArgumentException("Invalid argument. Object instance must NOT be null!");
        }
        T returnValue = null;
        try {
            PropertyDescriptor descriptor = new PropertyDescriptor(propertyName, instance.getClass());
            Method readMethod = descriptor.getReadMethod();
            if(readMethod == null) {
                throw new IllegalStateException("Property '" + propertyName + "' of " + instance.getClass().getName() + " is NOT readable!");
            }
            if(requiredType.isAssignableFrom(readMethod.getReturnType())) {
                try {
                    Object propertyValue = readMethod.invoke(instance);
                    returnValue = requiredType.cast(propertyValue);
                } catch (Exception e) {
                    e.printStackTrace(); // unable to invoke readMethod
                }
            }
        } catch (IntrospectionException e) {
            throw new IllegalArgumentException("Property '" + propertyName + "' is NOT defined in " + instance.getClass().getName() + "!", e);
        }
        return returnValue; 
    }

    public static boolean isValid(Collection<String> propertyValues, StringComparisonMode comparisonMode) {
        boolean ignoreCase = false;
        switch (comparisonMode) {
        case EQUAL_IGNORE_CASE:
        case NOT_EQUAL_IGNORE_CASE:
            ignoreCase = true;
        }

        List<String> values = new ArrayList<String> (propertyValues.size());
        for(String propertyValue : propertyValues) {
            if(ignoreCase) {
                values.add(propertyValue.toLowerCase());
            } else {
                values.add(propertyValue);
            }
        }

        switch (comparisonMode) {
        case EQUAL:
        case EQUAL_IGNORE_CASE:
            Set<String> uniqueValues = new HashSet<String> (values);
            return uniqueValues.size() == 1 ? true : false;
        case NOT_EQUAL:
        case NOT_EQUAL_IGNORE_CASE:
            Set<String> allValues = new HashSet<String> (values);
            return allValues.size() == values.size() ? true : false;
        }

        return true;
    }

    public static String resolveMessage(String[] propertyNames, StringComparisonMode comparisonMode) {
        StringBuffer buffer = concatPropertyNames(propertyNames);
        buffer.append(" must");
        switch(comparisonMode) {
        case EQUAL:
        case EQUAL_IGNORE_CASE:
            buffer.append(" be equal");
            break;
        case NOT_EQUAL:
        case NOT_EQUAL_IGNORE_CASE:
            buffer.append(" not be equal");
            break;
        }
        buffer.append('.');
        return buffer.toString();
    }

    private static StringBuffer concatPropertyNames(String[] propertyNames) {
        //TODO improve concating algorithm
        StringBuffer buffer = new StringBuffer();
        buffer.append('[');
        for(String propertyName : propertyNames) {
            char firstChar = Character.toUpperCase(propertyName.charAt(0));
            buffer.append(firstChar);
            buffer.append(propertyName.substring(1));
            buffer.append(", ");
        }
        buffer.delete(buffer.length()-2, buffer.length());
        buffer.append("]");
        return buffer;
    }
}

User

@CompareStrings(propertyNames={"password", "confirmPassword"})
public class User {
    private String password;
    private String confirmPassword;

    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }
    public String getConfirmPassword() { return confirmPassword; }
    public void setConfirmPassword(String confirmPassword) { this.confirmPassword =  confirmPassword; }
}

Test

    public void test() {
        User user = new User();
        user.setPassword("password");
        user.setConfirmPassword("paSSword");
        Set<ConstraintViolation<User>> violations = beanValidator.validate(user);
        for(ConstraintViolation<User> violation : violations) {
            logger.debug("Message:- " + violation.getMessage());
        }
        Assert.assertEquals(violations.size(), 1);
    }

Output Message:- [Password, ConfirmPassword] must be equal.

By using the CompareStrings validation constraint, we can also compare more than two properties and we can mix any of four string comparison methods.

ColorChoice

@CompareStrings(propertyNames={"color1", "color2", "color3"}, matchMode=StringComparisonMode.NOT_EQUAL, message="Please choose three different colors.")
public class ColorChoice {

    private String color1;
    private String color2;
    private String color3;
        ......
}

Test

ColorChoice colorChoice = new ColorChoice();
        colorChoice.setColor1("black");
        colorChoice.setColor2("white");
        colorChoice.setColor3("white");
        Set<ConstraintViolation<ColorChoice>> colorChoiceviolations = beanValidator.validate(colorChoice);
        for(ConstraintViolation<ColorChoice> violation : colorChoiceviolations) {
            logger.debug("Message:- " + violation.getMessage());
        }

Output Message:- Please choose three different colors.

Similarly, we can have CompareNumbers, CompareDates, etc cross-fields validation constraints.

P.S. I have not tested this code under production environment (though I tested it under dev environment), so consider this code as Milestone Release. If you find a bug, please write a nice comment. :)

Answer 4

I have tried Alberthoven's example (hibernate-validator 4.0.2.GA) and i get an ValidationException: „Annotated methods must follow the JavaBeans naming convention. match() does not.“ too. After I renamed the method from „match“ to "isValid" it works.

public class Password {

    private String password;

    private String retypedPassword;

    public Password(String password, String retypedPassword) {
        super();
        this.password = password;
        this.retypedPassword = retypedPassword;
    }

    @AssertTrue(message="password should match retyped password")
    private boolean isValid(){
        if (password == null) {
            return retypedPassword == null;
        } else {
            return password.equals(retypedPassword);
        }
    }

    public String getPassword() {
        return password;
    }

    public String getRetypedPassword() {
        return retypedPassword;
    }

}

Answer 5

With Hibernate Validator 4.1.0.Final I recommend using @ScriptAssert. Exceprt from its JavaDoc:

Script expressions can be written in any scripting or expression language, for which a JSR 223 ("Scripting for the JavaTM Platform") compatible engine can be found on the classpath.

Note: the evaluation is being performed by a scripting "engine" running in the Java VM, therefore on Java "server side", not on "client side" as stated in some comments.

Example:

@ScriptAssert(lang = "javascript", script = "_this.passVerify.equals(_this.pass)")
public class MyBean {
  @Size(min=6, max=50)
  private String pass;

  private String passVerify;
}

or with shorter alias and null-safe:

@ScriptAssert(lang = "javascript", alias = "_",
    script = "_.passVerify != null && _.passVerify.equals(_.pass)")
public class MyBean {
  @Size(min=6, max=50)
  private String pass;

  private String passVerify;
}

or with Java 7+ null-safe Objects.equals():

@ScriptAssert(lang = "javascript", script = "Objects.equals(_this.passVerify, _this.pass)")
public class MyBean {
  @Size(min=6, max=50)
  private String pass;

  private String passVerify;
}

Nevertheless, there is nothing wrong with a custom class level validator @Matches solution.

Answer 6

You guys are awesome. Really amazing ideas. I like Alberthoven's and McGin's most, so I decided to combine both ideas. And develop some generic solution to cater all cases. Here is my proposed solution.

@Documented
@Constraint(validatedBy = NotFalseValidator.class)
@Target({ElementType.METHOD, ElementType.FIELD,ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface NotFalse {


    String message() default "NotFalse";
    String[] messages();
    String[] properties();
    String[] verifiers();

    Class<?>[] groups() default {};

    Class<? extends Payload>[] payload() default {};

}

---

public class NotFalseValidator implements ConstraintValidator<NotFalse, Object> {
    private String[] properties;
    private String[] messages;
    private String[] verifiers;
    @Override
    public void initialize(NotFalse flag) {
        properties = flag.properties();
        messages = flag.messages();
        verifiers = flag.verifiers();
    }

    @Override
    public boolean isValid(Object bean, ConstraintValidatorContext cxt) {
        if(bean == null) {
            return true;
        }

        boolean valid = true;
        BeanWrapper beanWrapper = PropertyAccessorFactory.forBeanPropertyAccess(bean);

        for(int i = 0; i< properties.length; i++) {
           Boolean verified = (Boolean) beanWrapper.getPropertyValue(verifiers[i]);
           valid &= isValidProperty(verified,messages[i],properties[i],cxt);
        }

        return valid;
    }

    boolean isValidProperty(Boolean flag,String message, String property, ConstraintValidatorContext cxt) {
        if(flag == null || flag) {
            return true;
        } else {
            cxt.disableDefaultConstraintViolation();
            cxt.buildConstraintViolationWithTemplate(message)
                    .addPropertyNode(property)
                    .addConstraintViolation();
            return false;
        }

    }



}

---

@NotFalse(
        messages = {"End Date Before Start Date" , "Start Date Before End Date" } ,
        properties={"endDateTime" , "startDateTime"},
        verifiers = {"validDateRange" , "validDateRange"})
public class SyncSessionDTO implements ControllableNode {
    @NotEmpty @NotPastDate
    private Date startDateTime;

    @NotEmpty
    private Date endDateTime;



    public Date getStartDateTime() {
        return startDateTime;
    }

    public void setStartDateTime(Date startDateTime) {
        this.startDateTime = startDateTime;
    }

    public Date getEndDateTime() {
        return endDateTime;
    }

    public void setEndDateTime(Date endDateTime) {
        this.endDateTime = endDateTime;
    }


    public Boolean getValidDateRange(){
        if(startDateTime != null && endDateTime != null) {
            return startDateTime.getTime() <= endDateTime.getTime();
        }

        return null;
    }

}