Feature Request: "IllegalArgumentException: Path parameter XXX value must not be null." should include url

I was not properly setting a Path parameter and saw:

Caused by: java.lang.IllegalArgumentException: Path parameter "user_id" value must not be null.

The problem is that I have ~20 web requests all with the user_id path parameter. I have no easy way to diagnose which one I’m calling incorrectly. It would be great if that error message included the url.

I think it should be pretty easy to update Path to:

static final class Path<T> extends ParameterHandler<T> {
    @Override
    void apply(RequestBuilder builder, @Nullable T value) throws IOException {
        if (value == null) {
            throw new IllegalArgumentException(
                    "Path parameter \"" + name + "\" value must not be null in request "
                            + builder.baseUrl + builder.relativeUrl);
        }
        builder.addPathParam(name, valueConverter.convert(value), encoded);
    }
}

Probably worth updating all ParameterHandlers that throw when value is null.

For the record, calling a service method inside RxJava stream results in a stack trace that isn’t very helpful:

   io.reactivex.exceptions.OnErrorNotImplementedException: Path parameter "user_id" value must not be null.
        at io.reactivex.internal.functions.Functions$OnErrorMissingConsumer.accept(Functions.java:704)
        at io.reactivex.internal.functions.Functions$OnErrorMissingConsumer.accept(Functions.java:701)
        at io.reactivex.internal.observers.ConsumerSingleObserver.onError(ConsumerSingleObserver.java:47)
        at io.reactivex.internal.operators.single.SingleObserveOn$ObserveOnSingleObserver.run(SingleObserveOn.java:79)
        at io.reactivex.android.schedulers.HandlerScheduler$ScheduledRunnable.run(HandlerScheduler.java:109)
        at android.os.Handler.handleCallback(Handler.java:751)
        at android.os.Handler.dispatchMessage(Handler.java:95)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6121)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:889)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:779)
     Caused by: java.lang.IllegalArgumentException: Path parameter "user_id" value must not be null.
        at retrofit2.ParameterHandler$Path.apply(ParameterHandler.java:96)
        at retrofit2.ServiceMethod.toRequest(ServiceMethod.java:111)
        at retrofit2.OkHttpCall.createRawCall(OkHttpCall.java:184)
        at retrofit2.OkHttpCall.execute(OkHttpCall.java:168)
        at retrofit2.adapter.rxjava2.CallExecuteObservable.subscribeActual(CallExecuteObservable.java:41)
        at io.reactivex.Observable.subscribe(Observable.java:12025)
        at io.reactivex.internal.operators.observable.ObservableSubscribeOn$SubscribeTask.run(ObservableSubscribeOn.java:96)
        at io.reactivex.Scheduler$DisposeTask.run(Scheduler.java:571)
        at io.reactivex.internal.schedulers.ScheduledRunnable.run(ScheduledRunnable.java:66)
        at io.reactivex.internal.schedulers.ScheduledRunnable.call(ScheduledRunnable.java:57)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:272)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1133)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:607)
        at java.lang.Thread.run(Thread.java:761)

[tir38]

I’d be willing to work on this if I get a 👍

[tir38]

@vitorhugods thanks!