+1 to overridable function. Subclassing the whole Engine would be somewhat cumbersome to just set up errors for invalid variable cases.
Dne neděle 24. ledna 2021 v 18:20:58 UTC+1 uživatel tim.mc...@gmail.com napsal: > I was going to have a go at this ticket ( > https://code.djangoproject.com/ticket/28526) - which links this thread. > > Having read the various replies, it seems like there is no shortage of > differing views how missing/invalid variables should be treated: > - There should be no logging > - There should be logging, but full tracebacks are too noisy / not > beginner friendly > - Full tracebacks are useful > - There should be logging but only for the first time an invalid variable > is encountered within a template > - Some combination of the above with a setting (or settings) to alter > behaviour > - There should be a setting to make invalid variables raise errors > > There is a danger of bloating the number of options/settings and still not > catering for what everyone wants. > > One way to allow all of these would be to provide a hook to handle raising > errors/logging in the case of invalid variables. This would also allow all > kinds of custom behaviour, that might be useful for particular cases, but > which wouldn't warrant being features of django itself: > - log / raise only on particular templates > - provide different levels of logging depending on the type of the > invalid variable > - etc > > I originally thought of replacing `string_if_invalid` with an option > function `invalid_variable_handler` that points to a function, which would > return a string for invalid variables, and could also handle logging/errors > at the same time. Perhaps this is too many concerns for one function; > although having said that, it's really just one concern - handling > invalid/undefined variables. The default function could return > `string_if_invalid` during the interim whilst we add a deprecation warning > for `string_if_invalid`. > > A less destructive option would be to leave `string_if_invalid` as it is, > and just move the code that logs/raises errors to a public method > `handle_variable_resolve_errors` of Engine(?). This would provide a public > API for people to customise logging/raising of errors if they should so > wish, by sub-classing `Engine` (and then add an engine attribute to > DjangoTemplates??). > > Alternatively, `handle_variable_resolve_errors` could just be another > option which would point to the above function, rather than having to > subclass Engine. > > The very first of these approaches would allow useful things like > returning different `string_if_invalid` values for different templates, if > debug is on etc. But seems a bit messier. > > There are a few more variations on the same theme, in terms of actual > implementation, but the basic idea is the same - move logging/raising > errors to an overridable function. > > Any thoughts on this would be much appreciated > > On Friday, August 25, 2017 at 11:50:27 AM UTC+1 Vlastimil Zíma wrote: > >> If anyone is interested, I've cleaned the errors in admin templates: >> >> Ticket: https://code.djangoproject.com/ticket/28529 >> PR: https://github.com/django/django/pull/8973 >> >> The fixes are quite simple. The biggest problem is sometimes to find out, >> in which template the bug actually appears. >> >> Vlastik >> >> Dne pátek 25. srpna 2017 9:28:30 UTC+2 Vlastimil Zíma napsal(a): >> >>> Apparently there is number of errors in admin templates. I suggest to >>> fix the templates. I my experience, the most cases are missing if >>> statements or missing context variables. These can be fixed very easily and >>> produce cleaner templates. I consider this much better solution than just >>> ignoring error messages. >>> >>> As Anthony suggested, the main problem is more often the fuzziness of >>> the messages, which do not often properly state template, line or >>> expression which is incorrect. This makes it difficult to resolve them in >>> some cases. >>> >>> Vlastik >>> >>> Dne čtvrtek 24. srpna 2017 17:21:38 UTC+2 Tim Graham napsal(a): >>>> >>>> We received a report that shows the large number of undefined variable >>>> warnings when rendering an admin changelist page [0]. >>>> >>>> I'm still not sure what the solution should be, but I created #28526 >>>> [1] to track this problem: finding a remedy to the problem of verbose, >>>> often unhelpful logging of undefined variables. >>>> >>>> I don't think "the end goal of errors raising when using undefined >>>> variables" is feasible. My sense is that relying on the behavior of >>>> undefined variables is too entrenched in the Django template language to >>>> change it at this point. (If someone wanted to try to fix all the warnings >>>> in the admin templates, that might provide a useful data point). See the >>>> "Template handling of undefined variables" thread [2] for a longer >>>> discussion. >>>> >>>> [0] https://code.djangoproject.com/ticket/28516 >>>> [1] https://code.djangoproject.com/ticket/28526 >>>> [2] >>>> https://groups.google.com/d/topic/django-developers/LT5ESP0w0gQ/discussion >>>> >>>> On Tuesday, June 20, 2017 at 4:12:52 AM UTC-4, Anthony King wrote: >>>>> >>>>> -1 for removing logs. Like Vlastimil, it's helped me spot a couple of >>>>> stray bugs. >>>>> >>>>> What I'd actually like to see is this becoming stricter, with the end >>>>> goal of errors raising when using undefined variables. >>>>> >>>>> For the verbosity, perhaps there's a middle ground? only log once per >>>>> variable access per template context, and provide a formatter that will >>>>> clean up the output? >>>>> >>>>> I believe in debug mode, you have access to line numbers and character >>>>> positions, so the final output could look something like this: >>>>> >>>>> `` >>>>> some_app/home.html:32:24: Undefined variable: *missing_variable* >>>>> `` >>>>> >>>>> I'm unsure how much effort this would take, but it would definitely >>>>> make the logging a lot more user + developer friendly. >>>>> >>>>> On 20 June 2017 at 08:48, Vlastimil Zíma <vlas...@ziima.cz> wrote: >>>>> >>>>>> -1 to the removal. I was annoyed by the logging at first, but then I >>>>>> started to clean individual logs. Half way through, I found several >>>>>> usages >>>>>> of long removed variables, one unused template (as a side effect) and I >>>>>> updated several views to always provide defined context variables. >>>>>> >>>>>> All in all, I consider the warnings very useful for a cleaning, >>>>>> though I wouldn't be against an option to silence them. Which can >>>>>> already >>>>>> by accomplished by LOGGING, can't it? >>>>>> >>>>>> Vlastik >>>>>> >>>>>> Dne neděle 26. března 2017 11:14:23 UTC+2 Melvyn Sopacua napsal(a): >>>>>>> >>>>>>> On Thursday 16 March 2017 12:03:07 Tim Graham wrote: >>>>>>> >>>>>>> > Ticket #18773 [0] added logging of undefined template variables in >>>>>>> >>>>>>> > Django 1.9 [1], however, I've seen several reports of users finding >>>>>>> >>>>>>> > this logging more confusing than helpful. >>>>>>> >>>>>>> >>>>>>> >>>>>>> With channels hitting 2.0 and the already large stack of moving >>>>>>> parts surrounding Django you need some basic system administration >>>>>>> skills >>>>>>> and programming experience to work with the system. And there are quite >>>>>>> a >>>>>>> few examples to link to from the user's list that deal with those >>>>>>> moving >>>>>>> parts rather then Django itself. It is not an application that you >>>>>>> download, install and run. >>>>>>> >>>>>>> >>>>>>> >>>>>>> An introduction "What you need to know before starting Django" would >>>>>>> help a lot in this respect and explaining the noisiness of some logging >>>>>>> belongs in there. >>>>>>> >>>>>>> >>>>>>> >>>>>>> Because it *is* useful if you defined that variable to True in your >>>>>>> settings, and it's working in all projects but this one. It could be >>>>>>> there's an extra piece of context middleware that uses the same name >>>>>>> and >>>>>>> deletes the variable from the context. It could be there's a Mixin >>>>>>> missing >>>>>>> in the view hierarchy. Or a typo you don't notice anymore after plowing >>>>>>> through 20+ included template bits. >>>>>>> >>>>>>> >>>>>>> >>>>>>> Noisy logging is exactly what you want when debugging. It should log >>>>>>> things that may be working as designed, especially things that are >>>>>>> ambiguous (like undefined and false). >>>>>>> >>>>>>> >>>>>>> >>>>>>> Another thing is that logging is the ugly duckling of Django. It's >>>>>>> not mentioned much if at all in the tutorial. It is not mentioned at >>>>>>> all in >>>>>>> "How to write reusable apps" and it shows in the eco system. It's like >>>>>>> finding a diamond when an app actually has logging implemented. >>>>>>> >>>>>>> >>>>>>> >>>>>>> But it also means that novice users touching the LOGGING >>>>>>> configuration are exceptions and I don't think Django should cater to >>>>>>> the >>>>>>> exceptions. >>>>>>> >>>>>>> >>>>>>> >>>>>>> -- >>>>>>> >>>>>>> Melvyn Sopacua >>>>>>> >>>>>> -- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "Django developers (Contributions to Django itself)" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to django-develop...@googlegroups.com. >>>>>> To post to this group, send email to django-d...@googlegroups.com. >>>>>> Visit this group at https://groups.google.com/group/django-developers >>>>>> . >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/django-developers/80fafa13-ef3b-4b8c-9376-cc63b1776cb8%40googlegroups.com >>>>>> >>>>>> <https://groups.google.com/d/msgid/django-developers/80fafa13-ef3b-4b8c-9376-cc63b1776cb8%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. 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