Clarify use of "x-www-form-urlencoded" in reference documentation [SPR-8415]

[spring-projects-issues]

Rossen Stoyanchev opened SPR-8415 and commented

For "x-www-form-urlencoded" data one could use an @RequestBody (via FormHttpMessageConverter) or a @ModelAttribute method argument (via data binding). The latter has a few advantages:

• it results in a typed object rather than MultiValueMap
• with MultiValueMap you lose the ability to apply automatic validation
• use of request.getParameter*() before the @RequestBody argument is resolved causes problems

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Affects: 3.1 M1

Issue Links:

• resolveRequestBody algorithm does not take into account ConversionService when determining if binding is possible [SPR-6729] #11395 resolveRequestBody algorithm does not take into account ConversionService when determining if binding is possible
• Support for PUTting form-encoded data [SPR-5628] #10299 Support for PUTting form-encoded data

[spring-projects-issues]

Arjen Poutsma commented

use of request.getParameter*() before the @RequestBody argument is resolved causes problems

More specifically: doing request.getParameter() reads the entire request input stream, so there is nothing to convert from any more.

[spring-projects-issues]

Rossen Stoyanchev commented

A section has been added to the reference documentation on working with 'application/x-www-form-urlencoded' data recommending the use of @ModelAttribute for browser and for non-browser requests. The case of HTTP PUT requests where the ServletRequest prevents access to form data through the requestParameter*() family of ServletRequest methods is specifically covered as well (see #10299).

The sections on working with @ModelAttribute have also been updated.

[spring-projects-issues]

Arjan van B. commented

Would it make sense to add a note about NOT using HttpPutFormContentFilter in an application that also uses @RequestBody MultiValueMap<String, String> and/or HttpEntity<MultiValueMap<String, String>>?

(HttpPutFormContentFilter consumes the request's input stream, making the other methods fail. That is: if I am right in my comment at SPR-5628. Documentation is at Working with "application/x-www-form-urlencoded" data.)

[spring-projects-issues]

Rossen Stoyanchev commented

Yes, that makes sense. It would be very helpful if you submitted a pull request. You can do it directly in Github by using the Edit button.

[spring-projects-issues]

Arjan van B. commented

(Pull request for documentation submitted; #230)