[TYPO3-core] RFC: #9975: Bugfix: Typoscript: CONTENT | slide: multilanguage not correctly respected in content_fallback mode

[Bernhard Kraft]

Hello Stefan !

Be aware everyone! Do not expect to understand everything in this mail
if you are already up for more than 10 hours!! ;)

Stefan Galinski schrieb:
> Problem:
> The sliding functionality doesn't respect the content_fallback mode 
> correctly. It delivers always content elements from the fallback/calculated 
> language of the current selected page. The attached patch fixes this bug by 
> an additional overlay check of the page record which is referenced by the 
> content element.

The problem is relatively complex. It shoul be clarified that there are
two different ways of how the scenario "language" + "sliding" could get
handled/interpreted:
------------------------------------------------------------------------
*A* Slide down the rootline, until you find a page with current
language. If nothing is found, eventually slide down the rootline again
looking for elements of "content_fallback" language.

*B* Slide down the rootline, and on every depth check if there are
elements which could satisfy current "content_fallback" settings.
------------------------------------------------------------------------


The situation YOU described only occurs, when you have set

config.sys_language_mode = content_fallback
config.sys_language_overlay = 1

But you are correct: If you have &L=1 in your URL and visit a page which
hasn't got a translation,  then the fallback mode will switch
TSFE->sys_language_content to "0" (lets assume this easy case - when
there are only two languages) ...

now when sliding-back happens, it will always try to use content
elements with sys_language_uid=0 ... altough &L=1 was passed .... to
describe the problem somewhat easier ...

You patch properly fixes this problem, and I have no objections if you
are going to commit it this way. It will implement type *B*. So +1 from
me for your patch!!!

But it should get noted that the feature "sliding" + "languages" is not
completly finished with this patch.



Be aware: this does not cover all possible ways of translating a page.
It could be, someone didn't set "sys_language_overlay = 1". When this
flag IS set (like in your case), TYPO3 usually fetches all content
elements with sys_language_uid=0, and the performs the overlay.

So in this case it is a "must" that you translate your default-language
elements to the alternative language. So if you have 3 default-language
elements for example, you can't have 4 translated elements ...
(sys_language_parent of tt_content gets used here) ...

But if sys_language_overlay is NOT set, the CONTENT cObj usually simply
pulls all content elements having the requested sys_language_uid
directly, without overlay. In this case sliding-backwards now becomes
problematic. One would have to "re"-set TSFE->sys_language_content for
every depth again (storing the original value), to check if there are
content elements (to implement type  *B*)


So you see - it can get VERY tricky. Above descriptions only solve
variant *B* - it could still be someone requests variant *A* and we are
all totally fu**** up !!!


But anyways: you have a +1 from me to commit your variant to 4.3
(trunk), as it "slightly" changes behaviour it should not go into 4.2


greets,
Bernhard
-- 
Freiheit ist immer Freiheit des Andersdenkenden.
Rosa Luxemburg, 1871-1919
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www.think-open.at
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