tessl/maven-io-dropwizard--dropwizard-validation

Dropwizard Validation Support - provides enhanced validation capabilities for Dropwizard applications

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Method Validation

Name: tessl/maven-io-dropwizard--dropwizard-validation
Author: tessl

Annotations and utilities for validating method parameters and enabling bean predicate validation, supporting advanced validation scenarios beyond field-level constraints. This provides method-level validation capabilities for Dropwizard applications.

Capabilities

Validated Annotation

Specifies validation groups for method parameters and return values, extending beyond the limitations of standard @Valid annotation.

@Target({PARAMETER, METHOD})
@Retention(RUNTIME)
public @interface Validated {
    /**
     * Specify one or more validation groups to apply to the validation.
     *
     * @return Validation groups
     */
    Class<?>[] value() default {Default.class};
}

Usage Examples:

import io.dropwizard.validation.Validated;
import javax.validation.groups.Default;

public interface CreateUser {}
public interface UpdateUser {}

@Path("/users")
public class UserResource {
    
    @POST
    @Path("/create")
    public Response createUser(@Validated(CreateUser.class) UserData userData) {
        // Method parameter validated with CreateUser group
        return Response.ok().build();
    }
    
    @PUT
    @Path("/{id}")
    public Response updateUser(
        @PathParam("id") Long id,
        @Validated({UpdateUser.class, Default.class}) UserData userData
    ) {
        // Method parameter validated with both UpdateUser and Default groups
        return Response.ok().build();
    }
    
    @POST
    @Path("/batch")
    public Response createUsers(@Validated List<@Validated(CreateUser.class) UserData> users) {
        // Both the list and individual elements are validated
        return Response.ok().build();
    }
}

ValidationMethod Annotation

Validates bean predicate methods as returning true. Bean predicates must be of the form isSomething or they'll be silently ignored.

@Target({TYPE, ANNOTATION_TYPE, METHOD})
@Retention(RUNTIME)
@Constraint(validatedBy = MethodValidator.class)
public @interface ValidationMethod {
    /**
     * The validation message for this constraint.
     *
     * @return the message
     */
    String message() default "is not valid";

    /**
     * The groups the constraint belongs to.
     *
     * @return an array of classes representing the groups
     */
    Class<?>[] groups() default {};

    /**
     * The payloads of this constraint.
     *
     * @return the array of payload classes
     */
    Class<? extends Payload>[] payload() default {};
}

Usage Examples:

import io.dropwizard.validation.ValidationMethod;

public class UserConfiguration {
    private String username;
    private String password;
    private int age;
    private String email;
    
    @ValidationMethod(message = "Username and password cannot be the same")
    public boolean isUsernameAndPasswordDifferent() {
        return username == null || password == null || !username.equals(password);
    }
    
    @ValidationMethod(message = "User must be at least 18 years old")
    public boolean isAgeValid() {
        return age >= 18;
    }
    
    @ValidationMethod(message = "Email domain must be from approved list")
    public boolean isEmailDomainApproved() {
        if (email == null) return true;
        
        String[] approvedDomains = {"company.com", "partner.org", "trusted.net"};
        String domain = email.substring(email.lastIndexOf("@") + 1);
        
        return Arrays.asList(approvedDomains).contains(domain);
    }
    
    // getters and setters...
}

Advanced Usage

Combining Method Validation with Field Validation

import io.dropwizard.validation.ValidationMethod;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import javax.validation.constraints.Email;

public class RegistrationData {
    @NotNull
    @Size(min = 3, max = 50)
    private String username;
    
    @NotNull
    @Size(min = 8)
    private String password;
    
    @NotNull
    @Email
    private String email;
    
    private String confirmPassword;
    private boolean termsAccepted;
    
    // Method validation for business rules
    @ValidationMethod(message = "Password and confirmation must match")
    public boolean isPasswordConfirmed() {
        return password != null && password.equals(confirmPassword);
    }
    
    @ValidationMethod(message = "Terms and conditions must be accepted")
    public boolean isTermsAccepted() {
        return termsAccepted;
    }
    
    @ValidationMethod(message = "Username cannot be the same as email prefix")
    public boolean isUsernameUniqueFromEmail() {
        if (username == null || email == null) return true;
        
        String emailPrefix = email.substring(0, email.indexOf("@"));
        return !username.equalsIgnoreCase(emailPrefix);
    }
}