Clarify how to avoid favoring path extensions as well as deprecation warnings

[pgrisafi]

Affects: 5.2.4.RELEASE

According to 24179 favorPathExtension is deprecated, and we should all use the Accept header, which is perfect for me, since I always use favorPathExtension = false

The setter in ContentNegotiationManagerFactoryBean is Deprecated, but the field value is true (line 108) , so as far as I understand, the use of path seems in fact encouraged, since is the default value and the only way to set as false is Deprecated

Am I getting something wrong?

[rstoyanchev]

No, you're not.

This is very long standing behavior and changing the default can cause significant disruption but maintenance releases are intended to be trouble free so you can take advantage of fixes including security issues, if any.

The purpose of the deprecation and #24179 is:

1. Provide an advance warning for a change to come in the next minor release 5.3, see Deprecate use of path extensions in request mapping and content negotiation #24179.
2. Provide all options necessary to actually make the switch, which required a number of changes as you can see from the commits linked to Deprecate use of path extensions in request mapping and content negotiation #24179.

Note that even in 5.3 we will turn off automatic matching to all extensions, but continue to match explicitly registered extensions by default and so favorPathExtension will remain true. In the next minor or major release after that we'll consider completely removing path extension support. So it is a very phased approach.

[pgrisafi]

I'm not quite sure I understand, please correct me if I'm wrong.

I used to have an url like
/something/{email}
And expect a json back. In order to make it work with
/something/data@gmail.com
I needed to set up
configurer.favorPathExtension(false);

Now in order to do that I need to call a deprecated method.

In the future, I will not need to call any method, since this is going to be the default behaibour

[rstoyanchev]

That's a very good point but switching the default would likewise defeat the goal of a gradual migration through advance warning and deprecation.

It means we need to explain how to be configured which is:

// 1)
@Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) { 
    configurer.useRegisteredExtensionsOnly(true);
    configurer.replaceMediaTypes(Collections.emptyMap());
}

// 2)
@Override
public void configurePathMatch(PathMatchConfigurer configurer) {
    // the below will become the default values in 5.3
    configurer.useSuffixPatternMatch(false);
    configurer.useRegisteredExtensionsOnly(true);
}

1. Causes a path extension to never be resolved to a MediaType
2. Suppresses the use suffix pattern matching and tries registered extensions only of which there should be none.

[kev22257]

That's a very good point but switching the default would likewise defeat the goal of a gradual migration through advance warning and deprecation.

It means we need to explain how to be configured which is:

// 1)
@Override
public void configureContentNegotiation(ContentNegotiationConfigurer configurer) { 
    configurer.useRegisteredExtensionsOnly(true);
    configurer.replaceMediaTypes(Collections.emptyMap());
}

// 2)
@Override
public void configurePathMatch(PathMatchConfigurer configurer) {
    // the below will become the default values in 5.3
    configurer.useSuffixPatternMatch(false);
    configurer.useRegisteredExtensionsOnly(true);
}

1. Causes a path extension to never be resolved to a MediaType
2. Suppresses the use suffix pattern matching and tries registered extensions only of which there should be none.

I originally asked this same question on #24179, but I see you started to answer it here. Unfortunately with Spring 5.2.5 I cannot get 2) of your recommendation to work: there is no useSuffixPatternMatch or useRegisteredExtensionsOnly method in org.springframework.web.servlet.config.annotation.PathMatchConfigurer; I do see the old deprecated "set" versions of those methods, but I thought the suggestion here was how to get around the warnings before 5.3 is released.

[rstoyanchev]

I cannot get 2) of your recommendation to work: there is no useSuffixPatternMatch or useRegisteredExtensionsOnly method in org.springframework.web.servlet.config.annotation.PathMatchConfigurer

Indeed my bad.

Technically the proper thing to do would be to deprecate them in 5.3 when the defaults values will change and those methods can be avoided altogether.

That said I'd really like to keep the deprecations in 5.2 to maximize advance warning and provide extra time to adapt. Therefore in 5.2 applications will have to use these deprecated methods but as long as they are used to turn off suffix pattern matching, it's okay to suppress the deprecation warnings. Then in 5.3 we will change the default values (but not yet remove the config options), and at that applications can remove their use.

This is what I'll have to update the docs with.