Handle flash attributes on htmx redirects

[xhaggi]

This adds handling for flash attributes via RedirectAttributes. Now you can perform client-side redirects with htmx and the flash attributes work as with normal redirects.

Fixes #96

[xhaggi]

@wimdeblauwe there is a limitation, because the flash attribute processing does not work if HtmxResponse is set as model attribute (PR #128). I'm not sure if it was a good idea to support such a case and to be honest, I don't like it.

[xhaggi]

BTW @wimdeblauwe there is more magic done by RedirectView

• Treat the redirect URL as a URI template (default: true)
• Model attributes can be exposed as HTTP query parameters (default: true)
• Propagate the query params of the current URL. (default: false)

We could support all of them to behave as similarly as possible to Spring. Let me know what you think about it.

[checketts]

@wimdeblauwe there is a limitation, because the flash attribute processing does not work if HtmxResponse is set as model attribute (PR #128). I'm not sure if it was a good idea to support such a case and to be honest, I don't like it.

I couldn't find an alternative approach that was compatible with using JTE Models as the return. I'm happy to try another approach if you have any suggestions.

[xhaggi]

@checketts let's move the discussion about an alternative approach to the initial issue #127.

[wimdeblauwe]

BTW @wimdeblauwe there is more magic done by RedirectView

• Treat the redirect URL as a URI template (default: true)
• Model attributes can be exposed as HTTP query parameters (default: true)
• Propagate the query params of the current URL. (default: false)

We could support all of them to behave as similarly as possible to Spring. Let me know what you think about it.

If you are willing to implement that, it would be great if we align as much as possible with RedirectView I think.

[xhaggi]

If you are willing to implement that, it would be great if we align as much as possible with RedirectView I think.

Sure, but let's merge this before and I'll create a separate PR for it. Okay?

[wimdeblauwe]

ok, but can we already merge this? Don't we need a solution to #127 first?

[xhaggi]

I'm not sure because I need more information from @checketts on how he uses it in his projects. But if you ask me, we should revert #127 in favor of a better solution to his issue. It's definitely the wrong approach to render views in HtmxHandlerInterceptor#postHandle which was introduced by #127. And as far as I know, using JteModel as a return type is not a supported feature of Jte itself.

See https://jte.gg/spring-boot-starter-3/ or https://github.com/casid/jte/tree/main/jte-spring-boot-starter-3/src/main/java/gg/jte/springframework/boot/autoconfigure for more information about integration with Spring Boot.

[wimdeblauwe]

Ok, I agree that maybe it was bad judgement to have #127. If we merge this, it means @checketts is not blocked for now and we can have flash attributes, just not the combination of flashattributes and #127, right?

[xhaggi]

That's right.

[checketts]

I'm OK with that trade off. Sorry I've not been able to contribute much (been away working on building a physical building)

I'll re-open #127 and discuss the JTE specific needs and options there.