@RequestMapping narrowing based on presence of command object [SPR-4368]

[spring-projects-issues]

Andreas Schildbach opened SPR-4368 and commented

@RequestMapping largely takes the responsibilities of the former AbstractFormController.isFormSubmission().

Unfortunately, I stumbled upon some cases that are not handled yet by @RequestMapping (well).

1. Mapping only matches if command object is present / not present

I use this frequently if a have a form with http-method GET (e.g. read-only search forms). In this case, I cannot distinguish by method, and I do not want to distinguish by parameter (the naming of the parameters is up to Spring Binding / Tag Library).

2. Mapping only matches if parameter is not present

Although not needed as urgently as 1), it would make @RequestMappings easier to formulate and a bit more robust. For example, I see some cases where you want a parameter to be present, and on the other related mapping you want the parameter to not be present.

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Affects: 2.5.1

Issue Links:

• Request header filtering in @RequestMapping [SPR-5690] #10360 Request header filtering in @RequestMapping ("duplicates")

[spring-projects-issues]

Andreas Schildbach commented

3. Mapping only matches if a certain media type is accepted (via "Accept" header)

See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1

There are two specialities with this narrowing: One is the wildcarding mechanism, which is probably straight forward. The "relative quality factor" (q) requires not terminate matching on the first match, but to look for further matches with a higher quality factor.

[spring-projects-issues]

Juergen Hoeller commented

FYI, the @RequestMapping annotation supports "!myParam" expressions for non-presence of a specific parameter as well now.

I haven't researched options to support your other two suggestions yet.

Juergen

[spring-projects-issues]

Arjen Poutsma commented

Matching on headers is supported in M3, through the 'headers' element on @RequestMapping. See #10360.

[spring-projects-issues]

Arjen Poutsma commented

Changed title to reflect the one outstanding feature request in this issue.

[spring-projects-issues]

Arjen Poutsma commented

Most of the features requested in this issue have been resolved.

As for the matching if command object is present or not present, there are a couple of ways around this:

• You can assign the initial form retrieval to a different URL than the form submittal (i.e. GET /hotels/new or /hotels/edit). This is arguable better from a REST perspective anyway.
• Your handler method can handle the two cases in one, and just have a conditional if in your handler method, testing whether the submitted form is actually there.