Support for java.util.Optional as a @RequestPart [SPR-12644]

[spring-projects-issues]

Anderson Vaz opened SPR-12644 and commented

In issue #16448 was introduced support for java.util.Optional for @ResquestParam Controllers method parameters however it was not spread to @RequestPart parameters.
Attached is a project Spring Boot demonstrating the issue. When the parameter is @RequestPart and Optional, Spring can't convert the value.

I think that would be nice to have this feature implemented for @RequestPart parameters too.

Thanks!

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Affects: 4.1.3, 4.1.4

Reference URL: https://github.com/avaz/spring-bug-optional-requestpart.git

Issue Links:

• Support for java.util.Optional as a @RequestParam [SPR-11829] #16448 Support for java.util.Optional as a @RequestParam
• Second call to MVC handler method with Optional parameter fails with argument type mismatch [SPR-13755] #18328 Second call to MVC handler method with Optional parameter fails with argument type mismatch
• RequestPartMethodArgumentResolver should defensively handle MethodParameter nesting level and java.util.Optional access [SPR-13850] #18423 RequestPartMethodArgumentResolver should defensively handle MethodParameter nesting level and java.util.Optional access
• MultipartFile argument requires multipart request even when optional (and empty) [SPR-13849] #18422 MultipartFile argument requires multipart request even when optional (and empty)
• Support for java.util.Optional as a @RequestBody [SPR-15007] #19574 Support for java.util.Optional as a @RequestBody

[spring-projects-issues]

Juergen Hoeller commented

This turns out to be rather involved due to all the parameter type variants of @RequestPart, including the need to delegate to the registered HttpMessageConverters with a nested parameter type (which the infrastructure wasn't prepared for yet). So I'll keep it as a 4.2 feature, to be available in the next 4.2 snapshot tomorrow, going through the 4.2 RC phase.

Juergen