Form field labels change proposal

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Sergei Maertens

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Nov 11, 2015, 10:59:46 AM11/11/15
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This is a proposal to change how Django generates form field labels from model fields. Currently, `capfirst` is called on `field.verbose_name` (see https://github.com/django/django/blob/master/django/db/models/fields/__init__.py#L872). This behaviour has been around since pretty much forever and makes sense.

However, this affects what you put down in your translations - if a lowercased verbose name is what you want (and you translate it as such), Django will make your form labels uppercase and there's no clean way around that.

There is a very specific use case for this proposal. The house-style of a design states that all form labels should be lowercase - but names of the brand should be capitalized. Example: 'you agree to the Brand terms'. This is not easily feasible: css text-transform will also lowercase the brand name, and Django uppercases the first letter. Another possible use case could be if you insist on putting the labels to the right of the form input, but I will agree that looks silly.

So the proposal is to get rid of the capfirst call, and in the admin this could be mitigated for backwards compatibility by modifying the css to include:
label {
    text
-transform: capitalize;
}

This is ofcourse a fairly big backwards-incompatible change towards front-end/non-vendor code, as people now have to explicitly make sure that labels are capitalized in their own templates. So this should probably go through the usual deprecation mechanics (silent, warning, remove), if it happens at all.

What are current workarounds for this problem?
  • explicitly specifying the label value in the ModelForm definition: this violates the DRY principle, you already defined the verbose_name on the model field
  • creating a form mixin that will lowercase the first letter of the label for all fields
    • you still have to check if the first word if it's the Brand string, because then it should stay capitalized
    • you now have to include this mixin in every single form, and can no longer rely on implicitly generated form classes in generic CBV
  • create a templatefilter that decapitalizes the label, and re-capitalizes 'brand' occurrences to 'Brand' (currently implemented)
    • you now have to not forget this filter everywhere you render forms
    • performance hit if this is based on regular expressions (which in this case it is because subbrand should not become subBrand)
All in all, I'm of the opinion that the flexibility you gain by NOT manipulating the label in Django outweighs the backwards incompatible change. I'm also strongly of the opinion that capitalizing labels is something that should be done entirely in CSS - whether the label is capitalized, lower case or upper case shouldn't matter for Django's internals.

Reasons to not do this:
  • cater to common convention, not clients (quoted from #django-dev on irc): in my opinion this works 95% of the time, but your forced into violating some of Django's principles if you divert from this, most notably DRY
  • maintain backwards compatibility
Reasons to do this:
  • gain flexibility about the display of form labels
  • keep the codebase sane

Bonus: vaguely related ticket: https://code.djangoproject.com/ticket/5518

Tim Graham

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Nov 11, 2015, 11:32:57 AM11/11/15
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How do you envision putting this through a deprecation cycle?

Sergei Maertens

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Nov 11, 2015, 11:47:46 AM11/11/15
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I think I would start with locally creating a wrapper capfirst that is only called in the referenced line and https://github.com/django/django/blob/master/django/db/models/fields/__init__.py#L2069 (missed that one in the previous post) and possible other ocurrences. Emit a PendingDeprecationWarning, something along the lines of

def deprecated_capfirst(value):
    warnings.warn(
        "form field labels generated from model field 'verbose_name' will no longer automatically be capitalized",
        PendingDeprecationWarning, stacklevel=2
    )
    return capfirst(value)

and replace the capfirst with deprecated_capfirst ofcourse. At the same time, in the admin the CSS for labels can be added to text-transform them to capitalize.

In the next Django version this becomes loud, and in the next+1 version it is effectively removed.

As soon as the PendingDeprecation is added, the entry should be added to the docs with example CSS to make your own templates/styling capitalize the labels - and/or mention the `capfirst` template filter.

Thoughts?

Joeri

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Nov 11, 2015, 2:31:18 PM11/11/15
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I really don't like text-styling functions in Django that are (even indirectly) used in templates. CSS was made for this.

The solution Sergei proposed smoothly transitions the admin. However, alot of forms will be affected as well and thus alot of users.
The deprecation warning Sergei proposes warns people that upgrade to a new Django version about the change. A changelog suggestion to override the label or add some CSS should be straightforward and a small task compared to some other changes I've seen with previous upgrades.

And we get a cleaner Django, jeej.


Op woensdag 11 november 2015 17:47:46 UTC+1 schreef Sergei Maertens:

Aymeric Augustin

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Nov 11, 2015, 4:32:32 PM11/11/15
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I’ve always been annoyed by having to define lower case model field labels and capitalized form field labels. Inconsistencies always creep in. I would like to see this suggestion implemented, if we can provide a decent upgrade story for Django users.

-- 
Aymeric.



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Tim Graham

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Nov 19, 2015, 1:27:18 PM11/19/15
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How would a developer acknowledge/silence that deprecation warning? It seems to me that if it's emitted for every form field in a project that's not really going to be helpful.

Sergei Maertens

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Nov 19, 2015, 4:13:40 PM11/19/15
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Good catch.

I'm not sure, haven't there been similar cases in the past? First thing I can think of is using naive datetimes when timezone-support is enabled, and then you get a warning for each naive datetime you use, but that's of course different then a DeprecationWarning.

It's probably not best practice, but maybe it could be tracked with a module-level flag/constant, to check if the warning has been emited or not, ensuring that it gets only emited once during the lifetime of a thread?

Tim Graham

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Nov 19, 2015, 4:49:49 PM11/19/15
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The best solution I can think of at the moment would be a setting allowing users to opt-in to the new behavior which would then silence the warning. That leaves you with a defunct setting once the deprecation period completes. That's basically how SessionAuthenticationMiddleware worked when we decided to require it.

Sergei Maertens

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Nov 19, 2015, 4:52:57 PM11/19/15
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Yes, I've thought about a setting as well briefly but quickly discarded it because it would be 'yet another setting'. But this one would ofcourse be temporarily, and if that's been applied successfully in the past, then that's probably the best way to tackle this.

I'd be happy to write the patch for this myself if no objections turn up.

Tim Graham

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Nov 19, 2015, 5:23:48 PM11/19/15
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I'd like to see the admin's CSS updated under the assumption that this change moves forward to better understand the extent of changes that would be required from Django users to maintain the current behavior.

Sergei Maertens

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Nov 20, 2015, 11:38:53 AM11/20/15
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In https://github.com/django/django/blob/master/django/contrib/admin/static/admin/css/forms.css#L31, after
label {
   font
-weight: normal;
   color
:#666;
   font
-size:13px;
}

you would add
label::first-letter {
   text
-transform: capitalize;
}

(see https://css-tricks.com/almanac/selectors/f/first-letter/)

text-transform: capitalize on the label itself would capitalize all words, which is not wanted. The ::first-letter pseudo-selector is supported on all browsers, for IE 8 and lower you need a sigle colon instead of a double colon.

Tim Graham

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Nov 20, 2015, 2:31:55 PM11/20/15
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Looks easy enough. I was going to write, "Seems to me that there's more complexity in a deprecation path that requires a temporary opt-in setting rather than simply making the backwards incompatible change. Unless I missed something, adding CSS like that shouldn't cause problems for any apps maintaining compatibility with older versions of Django." but then I thought of a different case where it could be trickier to upgrade: developers who are specifying label='lower string' in some places to workaround the current behavior (but still want uppercased labels everywhere else). I guess the solution would be to use the text-transform rule you mentioned and another CSS rule targeting all labels IDs that you want to remain lowercased.

I'd like other opinions about whether or not a deprecation seems helpful for this. Personally, I'd rather just fix my CSS when upgrading rather than fix my CSS *and* add a setting for a few Django versions to silence the deprecation. I guess some people might like a few Django versions to update their CSS though (also we promised to try to provide fairly seamless upgrades from one LTS to the next).

sv...@maykinmedia.nl

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Jan 15, 2016, 10:46:48 AM1/15/16
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It has been said before but CSS was made for this and we should not mix content with design. I'd like to see this implemented with or without the deprecation path.

Sergei Maertens

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Jan 31, 2016, 4:30:09 PM1/31/16
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I've done the initial work for a patch, assuming a 'hard' change without deprecation path, the branch is here: https://github.com/sergei-maertens/django/commit/2f3c1d8dd56522dc69448ec20aac28d4ddc70ac4. Tests should be passing.

I've also taken a quick glance at django-admin-tools to check if they do anything special with decapitalizing/capitalizing things, but all seems to be well. Django injects the form css in the block extrastyle within change_form.html. For Grappelli/django-xadmin that block is present, but Grappelli overrides change_form.html, so that would probably need updating. I haven't looked at any other admin-theme packages, but the change would be trivial for them as well - providing a proper documentation notion.

The only things so far I'm not really sure of are:
  • Is deprecation required or not (input needed from other core devs I presume)
  • what with the validation error messages: as it stands, field labels are capitalized at the moment, and they're not in a <label> tag. Examples can be found in: django.db.models.base.Model.(date_error_message|unique_error_message)
In the tests I also noticed that there are cases where the label itself is not wrapped in a <label> tag (django.tests.forms_tests.tests.test_forms.FormsTestCase.test_templates_with_forms).

Tim Graham

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Apr 13, 2016, 12:47:45 PM4/13/16
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Took a quick look at djangoproject.com with this change. I noticed we're using the label to construct an input placeholder [0]. I think adapting that for this change isn't so easy to do in a cross-browser way via CSS [1] but we could add capfirst in the code.

The question of a deprecation seems to be whether it's better to ask every Django project opt into the new behavior in the next two releases via some temporary setting or if we force all projects to adapt their CSS (and possibly code, as the example above shows) for Django 1.10. I'm not too happy with either path.

I'm not sure about the validation messages. If we stop capitalizing the label, the message "%(field_label)s must be unique for" won't start with a capital anymore. On the other hand, capitalizing field_label is awkward if a custom message that doesn't put field_label at the start of the sentence is used.

[0] https://github.com/django/djangoproject.com/blob/7fd780c061e4244982ca5bdd914fd004c6fe90af/members/forms.py#L25
[1] http://stackoverflow.com/a/2610741/5112

Sergei Maertens

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Apr 13, 2016, 12:55:23 PM4/13/16
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Thanks for these specific use cases, I'll see if I can come up with some acceptable solutions in a reasonable time

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Sven R. Kunze

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Apr 13, 2016, 4:35:34 PM4/13/16
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Good evening everybody. :) I would like to reference this ticket: https://code.djangoproject.com/ticket/26497#comment:11

It appears we stumbled over this issue as well while designing a new model form. Quoting my comment from the ticket:


Would it make sense to separate concepts here?

1) user-defined verbose_name: Django should not touch it
2) auto-generated verbose_name: Django generates the verbose_name from the field's name


In both cases, once the label of a form field is set, Django should only touch it (except on the designers behalf).

Deprecation phase:
a) make global capitalization optional via settings (or form variable) with True as default for status quo.
b) auto-generated verbose_names are generated using a format string which can also be specified by a settings variable (or form variable). Default should result in current output (with the capitalization)
c) disable global capitalization by default


Does this makes sense?

Sergei Maertens

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Jul 2, 2016, 8:04:23 AM7/2/16
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So, this is the follow up from the discussion with Markus.

Implementation wise, we would only apply the capfirst on ModelForm fields if the model field has no explicit verbose_name set. That way, you can control the capitalization on the model level without having to specify it on the form again.

This could go through the usual deprecation cycle, with a warnings filter so that the warning is only emited once. An example of that already exists in the migrations: django.db.migrations.state.ModelState.render:
        ...
        with warnings.catch_warnings():
            warnings.filterwarnings(
                "ignore", "Managers from concrete parents will soon qualify as default managers",
                RemovedInDjango20Warning)
            ...

In our case, the 'ignore' would become 'once'.

The admin CSS would be updated to include the CSS selector for labels so that the capitalization is applied in CSS.

The placeholder issue for djangoproject.com would then have to be handled in the djangoproject.com code, unfortunately there's no easy way around that.

This gives the developer using Django full control over the labels in a DRY way.

This approach matches Sven's latest reply.

Sergei Maertens

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Jul 2, 2016, 9:21:34 AM7/2/16
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This is the reworked patch assuming the deprecation process was completed: https://github.com/django/django/compare/master...sergei-maertens:modelform-capfirst?expand=1


On Wednesday, November 11, 2015 at 4:59:46 PM UTC+1, Sergei Maertens wrote:

Tim Graham

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Jul 2, 2016, 9:28:58 AM7/2/16
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How would projects opt-in to the new behavior and silence the deprecation warning?

Sergei Maertens

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Jul 2, 2016, 10:03:14 AM7/2/16
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I am experimenting with warnings.filterwarnings('once', ...), which reduces the total warning output to 4 warnings, while there are about 10-15 calls. I haven't been able to completely silence it, probably because there are certain imports happening before a custom filter comes into pla

Opting in to the new behaviour is not covered. My personal feeling about this is that adding machinery to be able to opt in and silencing the warnings would be much more work than making the actual change. Extra settings were opted before, I don't like it because of the extra-machinery-reason I just mentioned. It *feels* as if it's either make the (backwards incompatible) change at once, or go through the entire deprecation cycle.

I'm open for suggestions, since obviously I don't have all the answers myself...

Sergei Maertens

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Jul 2, 2016, 10:08:41 AM7/2/16
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https://github.com/sergei-maertens/django/tree/capfirst-deprecation contains a simple POC with the warning filtering.

On a fairly large project with a lot of ModelForms and explicit verbose_name's, I see the warning three times on startup.

Sergei Maertens

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Jul 2, 2016, 1:04:02 PM7/2/16
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I've talked with some other core developers at the sprint, and the proposed flow is more in line with the initial proposal again:

* The deprecation cycle would include a settings (let's call it CAPFIRST_MODELFORM_LABEL), defaulting to False (the new behaviour). Users who wish to keep the old behaviour for a while set this to True
* The capfirst calls (there are 2 relevant ones) are replaced by wrappers that check the CAPFIRST_MODELFORM_LABEL setting. If it's set to True, the real capfirst is applied to field.verbose_name, else the raw field.verbose_name is returned.
* The Django admin css can be updated to include the CSS rule, so it looks still the same. Drawback is that this breaks tests if people are actively checking the labels/HTML for forms. The recommended approach here is to provide the capitalized strings in verbose_name
* For the front-end, the example CSS can be documented, or the option to capitalize the verbose_name.

Note that the new behaviour would be the default in the setting.

One other drawback I just thought of is that validation errors sometimes include the verbose_name (I think). This can look weird if the end-developer has specified a capitalized verbose_name, but that's also the case already. The recommended approach here would be to do the capitalizing in CSS.

On Saturday, July 2, 2016 at 3:28:58 PM UTC+2, Tim Graham wrote:

Daniele Procida

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Jul 3, 2016, 10:36:51 AM7/3/16
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On Sat, Jul 2, 2016, Sergei Maertens <sergeim...@gmail.com> wrote:

>I've talked with some other core developers at the sprint, and the proposed
>flow is more in line with the initial proposal again:
>
>* The deprecation cycle would include a settings (let's call it
>CAPFIRST_MODELFORM_LABEL), defaulting to False (the new behaviour). Users
>who wish to keep the old behaviour for a while set this to True
>* The capfirst calls (there are 2 relevant ones) are replaced by wrappers
>that check the CAPFIRST_MODELFORM_LABEL setting. If it's set to True, the
>real capfirst is applied to field.verbose_name, else the raw
>field.verbose_name is returned.
>* The Django admin css can be updated to include the CSS rule, so it looks
>still the same. Drawback is that this breaks tests if people are actively
>checking the labels/HTML for forms. The recommended approach here is to
>provide the capitalized strings in verbose_name
>* For the front-end, the example CSS can be documented, or the option to
>capitalize the verbose_name.
>
>Note that the new behaviour would be the default in the setting.

We've discussed this at the sprint; this seems like a pretty good approach to me. I'm not convinced by the label names, but that's a detail.

>One other drawback I just thought of is that validation errors sometimes
>include the verbose_name (I think). This can look weird if the
>end-developer has specified a capitalized verbose_name, but that's also the
>case already. The recommended approach here would be to do the capitalizing
>in CSS.

I think the main issue here is the possibility of weird-looking sentences coming out generally, but especially in languages that follow different rules from English.

Daniele

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