IllegalStateException: No API version attribute

[rstoyanchev]

When versionRequired is false and defaultVersion is not set, an IllegalStateException occurs if the selected endpoint has a version attribute.

Caused by: java.lang.IllegalStateException: No API version attribute
	at org.springframework.util.Assert.state(Assert.java:80)
	at org.springframework.web.servlet.mvc.condition.VersionRequestCondition.handleMatch(VersionRequestCondition.java:151)
	at org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.handleMatch(RequestMappingInfoHandlerMapping.java:134)
	at org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.handleMatch(RequestMappingInfoHandlerMapping.java:68)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.lookupHandlerMethod(AbstractHandlerMethodMapping.java:430)
	at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.getHandlerInternal(AbstractHandlerMethodMapping.java:376)
	at org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.getHandlerInternal(RequestMappingInfoHandlerMapping.java:116)
	at org.springframework.web.servlet.mvc.method.RequestMappingInfoHandlerMapping.getHandlerInternal(RequestMappingInfoHandlerMapping.java:68)

[DhruvTheDev1]

Spring's version request handler throws java.lang.IllegalStateException: No API version attribute as it expects either a default version or the API version to be explicitly required on requests.

@rstoyanchev Can I open a PR for this?

public void handleMatch(HttpServletRequest request) {
		if (this.version != null && !this.baselineVersion) {
			Comparable<?> version = (Comparable<?>) request.getAttribute(HandlerMapping.API_VERSION_ATTRIBUTE);
			Assert.state(version != null, "No API version attribute");
			if (!this.version.equals(version)) {
				throw new NotAcceptableApiVersionException(version.toString());
			}
		}
	}

Modify the method with a check for missing version attribute?
If version attribute is missing and versionRequired is false, skip exception but will need to add versionRequired field private final boolean versionRequired I believe.

Or just add if version is missing (version == null) then return so it avoids the exception when the version is missing.

[rstoyanchev]

@DhruvTheDev1 thanks for the offer, but I need to have a closer look before I can answer. It's also closely related to #35237 and the two need to be considered tother.

[DhruvTheDev1]

Hi @rstoyanchev
So #35237 Is focused on requests that don't specify an API version and when versioning is not introduced from the beginning, clients who haven't updated to include a version in their request might still work with the endpoints that don't require a version.

So if a client does not specify a version - spring should consider all mappings as a potential match and Spring should choose the one with the highest (most recent) version if versioning is involved and when versioning is introduced later, the clients that still using older requests should still work with the endpoints without a version in the mapping.

1. If versioning is introduced after the API is in use - some request might not have a version attribute hence in this case you don't want to throw an exception.
2. This issue is where Spring expects a version attribute but throws an exception and Prefer mapping without version for requests without a version #35237 is where requests without a version should still match endpoints that don't have versions, and the latest version mapping should be selected.

Potential Solution considering both issues - please give me your thoughts:
#35236 - Handling requests that don't include version attribute but Spring throws java.lang.IllegalStateException: No API version attribute
#35237 - If a request doesn't specify a version, Spring needs to find an endpoint that doesn't require a version.

When a request does not include a version:

• If the endpoint does not require the version - Spring matches the request
• If the endpoint does require a version but the request does not specify a version - Spring shouldn't throw an error and map to the most recent versionless endpoint.