#34077: Make BoundField renderable.
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Reporter: David Smith | Owner: nobody
Type: Uncategorized | Status: new
Component: Uncategorized | Version: 4.1
Severity: Normal | Keywords:
Triage Stage: Unreviewed | Has patch: 0
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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As of Django 4.1 Forms and Widgets (i.e. its `<input>`) are renderable
using the template engine. Django also has a strong concept of a field
with the `BoundField` class. This contains all of the information required
to render a field such as its label, errors, help text and its Widget.
Currently something like this is possible:
{{{
{% for field in form %}
{{ field.label_tag }}
{{ field }} # Note this is the widget!
{{ field.help_text }}
{% endfor %}
}}}
The current limitation is that each component of each field needs to be
rendered individually. It's fine when they are rendered all in the same
way as we can put them in a nice loop like above.
However, a reasonable request could be to have the `first name` and `last
name` on the same row (say). This would result in needing to do something
like the following. This would become even more verbose with errors being
introduced too:
{{{
<div class="row">
<div class="col">
{{ form.first_name.label }}
{{ form.first_name }}
{{ form.first_name.help_text }}
</div>
<div class="col">
{{ form.last_name.label }}
{{ form.last_name }}
{{ form.last_name.help_text }}
</div>
</div>
<div>
# more fields here
</div>
}}}
The proposal is that the `BoundField` should be a renderable object, this
could either be done by a new method (e.g. `field.as_field`) or maybe a
template filter (e.g `field|as_field`). We need the `as_field` (or another
function name) as the field on it's own currently renders the fields
widget rather than the whole field (i.e. incl label, help text , errors).
This would allow the above to be written as:
{{{
<div class="row">
<div class="col">
{{ form.first_name|as_field }}
</div>
<div class="col">
{{ form.last_name|as_field }}
</div>
</div>
<div>
# more fields here
</div>
}}}
A few initial thoughts on a possible implementation approach. This is not
fully thought out, but should hopefully be a helpful rough guide.
1. [https://github.com/django/django/blob/main/django/forms/fields.py#L82
Field] would learn a `template_name` attribute which can also be set via
it's `__init__`. Therefore in a form you would have:
{{{
class MyForm(forms.Form)
first_name = forms.CharField(max=10,
template_name="my_template_name.html")
}}}
2. Add a new method, either as a filter or as a new method to
[https://github.com/django/django/blob/d795259ea96004df0a2469246229a146307bcd2c/django/forms/boundfield.py#L14
BoundField] which renders the `BoundField` with it's fields template
(`boundfield.field.template_name`)
3. Consider if we need to provide a default implementation of this. If so
we should replicate the `div.html` templates. Specifically
[https://github.com/django/django/blob/d795259ea96004df0a2469246229a146307bcd2c/django/forms/templates/django/forms/div.html#L5-L21
these lines]. The `div.html` template can be updated to use this new
method.
4. If we do step 3 then the errors will likely be an issue as they
currently get rendered to a str in the form's
[https://github.com/django/django/blob/d795259ea96004df0a2469246229a146307bcd2c/django/forms/forms.py#L328-L348
get_context]. This may need breaking out into a separate function so it
can be called when rendering a field. `BoundField` know's about it's
associated form (`BoundField.Form`)
--
Ticket URL: <https://code.djangoproject.com/ticket/34077>
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