Forslag til validering i Jerseyressursar. Spesielt av former o.l.

ConcreteFormValidator.java

public class ConcreteFormValidator extends FormValidator<FormDTO> {
    private NumericStringValidator numericStringValidator;

    public ConcreteFormValidator(NumericStringValidator numericStringValidator) {
        this.numericStringValidator = numericStringValidator;
    }

    @Override
    public List<Message> validate(FormDTO form) {
        return collectMessages(this.numericStringValidator.validate(form.getA(), "first"),
                               this.numericStringValidator.validate(form.getB(), "second"));
    }
}

ConcreteFormValidatorTest.java

public class ConcreteFormValidatorTest {

    private ConcreteFormValidator formValidator;

    @Before
    public void setUp() {
        formValidator = new ConcreteFormValidator(new NumericStringValidator());
    }

    @Test
    public void should_validate() {
        List<Message> messages = formValidator.validate(new FormDTO("a", "1"));

        assertEquals(messages.size(), 1);

        assertEquals(messages.get(0).getField(), "first");
        assertEquals(messages.get(0).getKey(), "some.error.string");
        assertEquals(messages.get(0).getValue(), "a");
        assertEquals(messages.get(0).getType(), MessageType.FAILED);
    }

    @Test
    public void should_throw() {
        try {
            formValidator.validateAndThrow(new FormDTO("a", "1"));

            fail();
        } catch (ResourceValidationException e) {
            List<Message> messages = e.getMessages();
            assertEquals(messages.size(), 1);

            assertEquals(messages.get(0).getField(), "first");
            assertEquals(messages.get(0).getKey(), "some.error.string");
            assertEquals(messages.get(0).getValue(), "a");
            assertEquals(messages.get(0).getType(), MessageType.FAILED);
        }
    }

    @Test
    public void should_pass() {
        formValidator.validateAndThrow(new FormDTO("1", "3"));
    }
}

FormDTO.java

public class FormDTO {
    private String a;
    private String b;

    public FormDTO(String a, String b) {
        this.a = a;
        this.b = b;
    }

    public String getA() {
        return a;
    }

    public String getB() {
        return b;
    }
}

FormValidator.java

public abstract class FormValidator<T> {
    public abstract List<Message> validate(T t);

    public void validateAndThrow(T t) {
        List<Message> messages = validate(t);
        if (!messages.isEmpty()) {
            throw new ResourceValidationException(messages);
        }
    }

    protected List<Message> collectMessages(Message... messages) {
        List<Message> collected = new ArrayList<Message>();
        for (Message message : messages) {
            if (message != null) {
                collected.add(message);
            }
        }
        return collected;
    }
}

Message.java

public class Message {
    private String field;
    private String key;
    private String value;
    private MessageType type;

    public Message(String field, String key, String value, MessageType type) {
        this.field = field;
        this.key = key;
        this.value = value;
        this.type = type;
    }

    public String getField() {
        return field;
    }

    public String getKey() {
        return key;
    }

    public String getValue() {
        return value;
    }

    public MessageType getType() {
        return type;
    }
}

MessageType.java

public enum MessageType {
    SUCCESS, FAILED
}

NumericStringValidator.java

public class NumericStringValidator extends PrimitiveValidator<String> {
    @Override
    public Message validate(String numericString, String field) {
        if (!isNumeric(numericString)) {
            return new Message(field, "some.error.string", numericString, MessageType.FAILED);
        }
        return null;
    }
}

PrimitiveValidator.java

public abstract class PrimitiveValidator<T> {
    public abstract Message validate(T t, String field);
}

ResourceValidationException.java

public class ResourceValidationException extends RuntimeException {
    private List<Message> messages;

    public ResourceValidationException(List<Message> messages) {
        this.messages = messages;
    }

    public List<Message> getMessages() {
        return messages;
    }
}