Bean Validation with JAX-RS (rest-easy): parameter name not recognized - jax-rs

Question

I'm using JAX-RS resources with Bean Validation and integration between these two works as expected.
However, the default error messages generated in case of a validation error report parameter names as arg0, like so
[PARAMETER]
[login.arg0.password]
[password is required]
[]
Corresponding method definition:
#POST //and other JAX-RS annotations
public Response login(
#NotNull
#Valid
LoginBody loginBody) {
[...]
protected static class LoginBody {
#NotNull(message = EMAIL_REQUIRED)
public String email;
#NotNull(message = PASSWORD_REQUIRED)
public String password;
}
While I'm generally fine with this message pattern, what actually is annyoing, is the fact that the original parameter name is not recognized, i. e. I'd rather like to see
login.loginBody.password instead of arg0.
Is there an easy way to fix this, e. g. somehow provide an explicit name for that parameter?
I'm using WildFly Swarm 2017.6.0. From what I found out this means I have resteasy + resteasy-validator + hibernate-validator
Thanks.

Answer 1

You could try to compile your app with -parameters or instruct your IDE to do so, e.g. in case of
eclipse: preferences -> java -> compiler -> "store information about method parameters (usable via reflection)"
With that in place you then need to instruct the Bean Validation infrastructure (e.g. ) hibernate-validator to
use the ReflectiveParameterNamer via META-INF/validation.xml.
<parameter-name-provider>org.hibernate.validator.parameternameprovider.ReflectionParameterNameProvider</parameter-name-provider>
See also Hibernate Validator Configuration
I got something reliably working with the Paranamer library
META-INF/validation.xml:
<?xml version="1.0" encoding="UTF-8"?>
<validation-config
xmlns="http://jboss.org/xml/ns/javax/validation/configuration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://jboss.org/xml/ns/javax/validation/configuration
validation-configuration-1.1.xsd"
version="1.1">
<default-provider>org.hibernate.validator.HibernateValidator
</default-provider>
<message-interpolator>org.hibernate.validator.messageinterpolation.ResourceBundleMessageInterpolator
</message-interpolator>
<traversable-resolver>org.hibernate.validator.internal.engine.resolver.DefaultTraversableResolver
</traversable-resolver>
<constraint-validator-factory>org.hibernate.validator.internal.engine.constraintvalidation.ConstraintValidatorFactoryImpl
</constraint-validator-factory>
<parameter-name-provider>org.hibernate.validator.parameternameprovider.ParanamerParameterNameProvider</parameter-name-provider>
</validation-config>
To get paranamer working with wildfly I needed to create a parameter-namer jboss-module
and reference that module from the module.xml of the hibernate-validator module.
With that in place I could simply write:
#POST
public Response login(#NotNull #Valid #Named("authRequest") AuthRequest authRequest) {
return Response.ok().build();
}
...
public class AuthRequest {
#NotNull(message = AuthMessages.EMAIL_REQUIRED)
public String email;
#NotNull(message = AuthMessages.PASSWORD_REQUIRED)
public String password;
}
which yields the following response for a request sent via curl:
curl -H "Content-Type: application/json" -H "Accept: application/json" -d '{"email":"foo#bar.com"}' -v http://localhost:8080/javaweb-training/resources/auth
Response:
{"exception":null,"fieldViolations":[],"propertyViolations":[],"classViolations":[],"parameterViolations":[{"constraintType":"PARAMETER","path":"login.authRequest.password","message":"password.required","value":""}],"returnValueViolations":[]}%
... note login.authRequest.password instead of just login.arg0.password

Answer 2

There is a very simple solution: you can set your own error message in the constraint definition as follows
#NotNull(message = "password is required")
If you want a more generic solution based on the JAX-RS parameter annotations you can implement your own simple ParameterNamProvider and register it in validation.xml as follows. This has the advantage of not having to change the jboss module structure. I also didn't have to change any compiler flags...
public class AnnotatedParameterNameProvider implements ParameterNameProvider {
#Override
public List<String> getParameterNames(Constructor<?> constructor) {
return lookupParameterNames(constructor.getParameterAnnotations());
}
#Override
public List<String> getParameterNames(Method method) {
return lookupParameterNames(method.getParameterAnnotations());
}
private List<String> lookupParameterNames(Annotation[][] annotations) {
final List<String> names = new ArrayList<>();
if (annotations != null) {
for (Annotation[] annotation : annotations) {
String annotationValue = null;
for (Annotation ann : annotation) {
annotationValue = getAnnotationValue(ann);
if (annotationValue != null) {
break;
}
}
// if no matching annotation, must be the request body
if (annotationValue == null) {
annotationValue = "requestBody";
}
names.add(annotationValue);
}
}
return names;
}
private static String getAnnotationValue(Annotation annotation) {
if (annotation instanceof HeaderParam) {
return ((HeaderParam) annotation).value();
} else if (annotation instanceof PathParam) {
return ((PathParam) annotation).value();
} else if (annotation instanceof QueryParam) {
return ((QueryParam) annotation).value();
}
return null;
}
}
In validation.xml:
<validation-config xmlns="http://jboss.org/xml/ns/javax/validation/configuration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://jboss.org/xml/ns/javax/validation/configuration validation-configuration-1.1.xsd"
version="1.1">
<parameter-name-provider>com.yourcompany.providers.AnnotatedParameterNameProvider</parameter-name-provider>
</validation-config>
Note that you can also customize how the error message is formatted by implementing your own MessageInterpolator and registering it in the validation.xml

Answer 3

Can you try to implement an exception mapper for ConstraintViolationExceptions and see if the information you have there (the list of constraint violations) can help you to obtain the parameter name?

Answer 4

Updated version of #thomas-darimont for Hibernate Validator 6.X.
Variant#1 - with build in Java 8 (using -parameters compile parameter)
Specify dependencies (gradle example):
// Define explicit hibernate validator 6.x
implementation('org.hibernate.validator:hibernate-validator:6.0.13.Final')
implementation('org.jboss.resteasy:resteasy-validator-provider-11:3.6.2.Final') {
// Exclude transitive hibernate validator 5.x
exclude group: 'org.hibernate', module: 'hibernate-validator'
}
Specify validator(s):
#GET
#Path("user/{userId}")
public Response getUser(#Size(min = 2) #PathParam("userId") String userId) {
return null;
}
Note: org.hibernate.validator.internal.engine.DefaultParameterNameProvider will return parameter names obtained from the Java reflection API.
Variant #2 - use ParaNamer library. (xml configuration)
In case you don't want to be dependant on compilation flag.
Specify dependencies (gradle example):
// Define explicit hibernate validator 6.x
implementation('org.hibernate.validator:hibernate-validator:6.0.13.Final')
implementation('org.jboss.resteasy:resteasy-validator-provider-11:3.6.2.Final') {
// Exclude transitive hibernate validator 5.x
exclude group: 'org.hibernate', module: 'hibernate-validator'
}
// ParaNamer library
implementation('com.thoughtworks.paranamer:paranamer:2.8')
Specify validator(s):
#GET
#Path("user/{userId}")
public Response getUser(#Size(min = 2) #PathParam("userId") String userId) {
return null;
}
Put <project_dir>/src/main/resources/META-INF/validation.xml
<?xml version="1.0" encoding="UTF-8"?>
<validation-config
xmlns="http://xmlns.jcp.org/xml/ns/validation/configuration"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/validation/configuration
http://xmlns.jcp.org/xml/ns/validation/configuration/validation-configuration-2.0.xsd"
version="2.0">
<parameter-name-provider>org.hibernate.validator.parameternameprovider.ParanamerParameterNameProvider</parameter-name-provider>
</validation-config>
Note: Since Hibernate Validator 6.x org.hibernate.validator.parameternameprovider.ReflectionParameterNameProvider is deprecated, use org.hibernate.validator.parameternameprovider.ParanamerParameterNameProvider instead.
Question: Can I configure this with Java-code style only?
Unfortunately, no. (See details here).