Django templates stripping spaces?

问题

I'm having trouble with Django templates and CharField models.

So I have a model with a CharField that creates a slug that replaces spaces with underscores. If I create an object, Somename Somesurname, this creates slug Somename_Somesurname and gets displayed as expected on the template.

However, if I create an object, Somename Somesurname (notice the second space), slug Somename__Somesurname is created, and although on the Django console I see this as <Object: Somename Somesurname>, on the template it is displayed as Somename Somesurname.

So do Django templates somehow strip spaces? Is there a filter I can use to get the name with its spaces?

回答1:

Let me preface this by saying @DNS's answer is correct as to why the spaces are not showing.

With that in mind, this template filter will replace any spaces in the string with  

Usage:

{{ "hey there  world"|spacify }}

Output would be hey there  world

Here is the code:

from django.template import Library
from django.template.defaultfilters import stringfilter
from django.utils.html import conditional_escape
from django.utils.safestring import mark_safe
import re

register = Library()

@stringfilter
def spacify(value, autoescape=None):
    if autoescape:
    esc = conditional_escape
    else:
    esc = lambda x: x
    return mark_safe(re.sub('\s', '&'+'nbsp;', esc(value)))
spacify.needs_autoescape = True
register.filter(spacify)

For notes on how template filters work and how to install them, check out the docs.

回答2:

Django sees the object internally as having two spaces (judging by the two underscores and two spaces in the repr output). The fact that it only shows up with one space in the template is just how HTML works. Notice how, in the question you just asked, most of the places where you entered two spaces, only one is showing up?

From the HTML4 Spec:

In particular, user agents should collapse input white space sequences when producing output inter-word space.

As S.Lott suggested, you can verify that my guess is correct by adding debug logging, or using the Firebug plugin for Firefox or something similar, to see exactly what's getting sent to the browser. Then you'll know for sure on which end the problem lies.

If multiple spaces are really important to you, you'll need to use the   entity, though I don't know offhand how you'd get Django to encode the output of that specific object using them.

回答3:

There is a built-in template tag spaceless

{% spaceless %}
    <p>
        <a href="foo/">Foo</a>
    </p>
{% endspaceless %}

Which results:

<p><a href="foo/">Foo</a></p>

回答4:

Slugify removes all leading spaces, you'll need to rewrite this as a custom template tag to get the behaviour you're after. The original filter code looks like this

def slugify(value):
   """
   Normalizes string, converts to lowercase, removes non-alpha characters,
   and converts spaces to hyphens.
   """
   import unicodedata
   value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore')
   value = unicode(re.sub('[^\w\s-]', '', value).strip().lower())
   return mark_safe(re.sub('[-\s]+', '-', value))

which changes "some string" into "some-string" killing the extra whitespace. You could change it like so:

def new_slugify(value):
   """
   Normalizes string, converts to lowercase, removes non-alpha characters,
   and converts spaces to hyphens, does not remove leading whitespace.
   """
   import unicodedata
   value = unicodedata.normalize('NFKD', value).encode('ascii', 'ignore')
   value = unicode(re.sub('[^\w\s-]', '', value).strip().lower())
   return mark_safe(re.sub('[-\s]', '-', value))

Which will result in the following behaviour: "Some String here" to "some--string-here"

You still might have problems as mentioned before with how html treats extra whitespace, you'd have to write another, deslugify filter.

回答5:

This tag keeps spaces and newlines. I copied Django's own tag linebreaksbr and then added a line to replace the spaces with nbsp. It does not replace single spaces so text source is still readable. I wrote this because I couldn't get the spacify tag (other answer) to work with linebreaksbr.

from django.template.defaultfilters import stringfilter
from django.utils.safestring import mark_safe, SafeData
from django.utils.text import normalize_newlines
from django.utils.html import escape

@register.filter(is_safe=True, needs_autoescape=True)
@stringfilter
def keep_spacing(value, autoescape=None):
    autoescape = autoescape and not isinstance(value, SafeData)
    value = normalize_newlines(value)
    if autoescape:
        value = escape(value)
    value = mark_safe(value.replace('  ', ' &nbsp;'))             
    return mark_safe(value.replace('\n', '<br />'))

回答6:

'\s' might be ok in the use case described above, but be careful, this replaces other whitespaces like '\t' or '\n' as well! If this is not what you want, just use " " instead.

回答7:

For someone having issue with django template try this : I had a similar issue with my <optgorup> tag, i am getting my values from django model to display under select. I simple used '' around label option to get the complete text with space.<optgroup label='{{key}}'>

来源：https://stackoverflow.com/questions/721035/django-templates-stripping-spaces

标签

python

django

django-templates