Hi James,

Feel free to publish this back to the mailing list, if you'd like. Thanks for the example, I have some follow-up questions:

• How does the class get hooked up to the rest of the framework? Is it through the @Provider annotation? 

• Do you need to have multiple ParamConverterProviders? i.e. one for for integers, strings, lists, enums, etc? If you want to handle multiple types as parameters

• I see in your example that there is a clause if (!rawType.isEnum()) - does that mean that every single ParamConverterProvider is applied to every single parameter? If you have 100 providers, could this cause performance issues? Is there a way to associate a converter provider to a particular type? 

Thanks for the help,

Arwin

---

From: James Perkins <jperkins@redhat.com>
Sent: January 25, 2022 5:13 PM
To: Arwin Tio <arwin.tio@hotmail.com>
Subject: Re: [resteasy] How to show helpful error messages for malformed @QueryParam?

 

Hi Arwin,

I meant to reply to the list, but I guess I just replied directly instead :) I apologize for that. I'll keep it private for now in case you don't want any of the information public.

What you could use is a ParamConverter. Something like this may work https://gist.github.com/jamezp/aad75e83760f565f15f4f0b54e202620.

On Tue, Jan 25, 2022 at 5:03 PM Arwin Tio <arwin.tio@hotmail.com> wrote:

Hi James,

Thanks for the reply. Sorry, there is a mistake in my example. In my particular case, I have an endpoint that takes a "status" enum:

localhost:8080/api/v1/users?status=creating

But when I use the wrong status, it will throw an exception:

java.lang.IllegalArgumentException: No enum constant com.data.model.UserStatus.creating
	at java.base/java.lang.Enum.valueOf(Enum.java:273)

But the client will only receive a 404, with no error message.  What I was trying to say in the original email was, if number_param received something like a String:

localhost:8080/api/v1/users?number_param=asdf

Then it will also return a 404 as a client error, due to this exception

Caused by: java.lang.NumberFormatException: For input string: "asdf"
	at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)

What I am trying to figure out, is, instead of an opaque 404, I would like to set it up to return helpful error messages to the client, such as:

• 'number_param' received 'asdf', expected a number/integer instead of a string
  
• 'status' received 'creating', valid values are ['created', 'pending', 'complete']

Thanks,

Arwin

---

From: James Perkins <jperkins@redhat.com>
Sent: January 25, 2022 4:31 PM
To: Arwin Tio <arwin.tio@hotmail.com>
Subject: Re: [resteasy] How to show helpful error messages for malformed @QueryParam?

 

Hello Arwin,

Sorry for the late reply. What kind of argument is "123"? What I mean is it a linked to an enum or special value of some sort?

On Fri, Jan 21, 2022 at 9:05 AM Arwin Tio <arwin.tio@hotmail.com> wrote:

As I understand it, a malformed @QueryParam will return a 404 with no message. For example, localhost:8080/api/v1/users?number_param=123 will respond with 404. Apparently, this is due to the JAX-RS spec:

```
3.2 Fields and Bean Properties

if the field or property is annotated with @MatrixParam, @QueryParam or @PathParam then an implementation MUST generate an instance of NotFoundException (404 status) that wraps the thrown exception and no entity
```

I would like the modify this behavior to:

1. Return a 400 status code, as I believe 404 causes confusion for users (they will think the endpoint doesn't exist)
2. Show a helpful error message, for example "'123' is an invalid input for number_param, expected number"

I have read that the way to do this is with the ExceptionMapper<E extends Throwable> interface. Is this true? And if so, which Exception E should I use? Is there something like a QueryParamException?

If it matters, I am using RESTEasy with Quarkus.

Thanks,

Arwin
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--

James R. Perkins

JBoss by Red Hat

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James R. Perkins

JBoss by Red Hat