templatetags and refresh

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Wim Feijen

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Jun 22, 2011, 9:32:10 AM6/22/11
to Django users
Hello,

At www.mkb-rotterdam.nl we use a template tag to display NewsItems in
different formats on the homepage.

However, when a new NewsItem is added, it does not appear at once.

Might this have to do with the fact that we use a template tag to get
the NewsItems out of the db?

Our query is:

newsitems = NewsItem.objects.filter(Q(expires_at__gt = datetime.now())
| Q(expires_at__isnull = True), effective_at__lte = datetime.now(),
is_active=True).order_by('-news_timestamp')

Or is datetime.now() fixed to the past?

What would be a proper way to solve this then? Maybe add a post-save
signal but how could we use this then to refresh the tag?

If something else is the matter, or just if you're interested: we host
our site using a virtual apache + mod_wsgi + nginx.

Thanks for your help!

Wim


Michał Sawicz

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Jun 22, 2011, 11:49:33 AM6/22/11
to django...@googlegroups.com
Dnia 2011-06-22, śro o godzinie 06:32 -0700, Wim Feijen pisze:

> Our query is:
>
> newsitems = NewsItem.objects.filter(Q(expires_at__gt = datetime.now())
> | Q(expires_at__isnull = True), effective_at__lte = datetime.now(),
> is_active=True).order_by('-news_timestamp')
>
> Or is datetime.now() fixed to the past?

You're probably gonna have to elaborate on your code, but did you try
datetime.now without calling it? IIUC that helps here and there, not
sure it will in your particular case.
--
Michał (Saviq) Sawicz <mic...@sawicz.net>

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Daniel Roseman

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Jun 22, 2011, 2:24:42 PM6/22/11
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Please show the full code for the templatetag.
--
DR. 

Wim Feijen

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Jun 24, 2011, 5:57:12 AM6/24/11
to Django users
Thanks!

That helped. :)

The code for the tag was as follows:

import re

from django.template import Variable, VariableDoesNotExist, Node,
Library, Template, TemplateSyntaxError, Context, loader
from django.conf import settings
from django.utils.safestring import mark_safe
from django.utils.html import escape
from django.utils.translation import ugettext as _

register = Library()

from cms.news.models import NewsItem
from django.db.models import Q
from datetime import datetime

try:
# newsitems = NewsItem.objects.all().order_by('-created_at')
# newsitems = NewsItem.objects.visible().order_by('-
news_timestamp')
newsitems = NewsItem.objects.filter(Q(expires_at__gt =
datetime.now()) | Q(expires_at__isnull = True), effective_at__lte =
datetime.now(), is_active=True).order_by('-news_timestamp')
except:
newsitems = None

class NewsItemBlockNode(Node):
def __init__(self, identifier, field):
self.identifier = str(identifier)
self.field = str(field)
self.image = False

def render(self, context):
global newsitems

number = -1
numbers = {
'large': 0,
'large-small': 0,
'small1': 1,
'small2': 2,
'small3': 3,
'small4': 4,
'medium': 5,
}

# Only image
if self.field == 'teaser-image':
self.field = 'teaser'
self.image = True

if self.identifier in numbers:
number = numbers[self.identifier]

try:
newsitem = getattr(newsitems[number], self.field)

if type(newsitem).__name__ == 'datetime':
if self.identifier in ['medium', 'large']:
newsitem = newsitem.strftime('%d [%m] %Y')

newsitem = newsitem.replace('[01]', 'januari')
newsitem = newsitem.replace('[02]', 'februari')
newsitem = newsitem.replace('[03]', 'maart')
newsitem = newsitem.replace('[04]', 'april')
newsitem = newsitem.replace('[05]', 'mei')
newsitem = newsitem.replace('[06]', 'juni')
newsitem = newsitem.replace('[07]', 'juli')
newsitem = newsitem.replace('[08]', 'augustus')
newsitem = newsitem.replace('[09]', 'september')
newsitem = newsitem.replace('[10]', 'oktober')
newsitem = newsitem.replace('[11]', 'november')
newsitem = newsitem.replace('[12]', 'december')

newsitem = newsitem.upper()
else:
newsitem = newsitem.strftime('%d-%m-%Y')

if self.image:
# Filter only image
src = re.search('<img(.+)src="(.*?)"(.+)/>', newsitem)

if src and src.group(2):
newsitem = src.group(2)
else:
newsitem = '/media/site/img/blank.gif'
elif self.field == 'teaser':
# Filter image
newsitem = re.sub('<img (.+) />', '', newsitem)
newsitem = re.sub('<a.*?>', '', newsitem)
newsitem = re.sub('</a>', '', newsitem)
newsitem = re.sub('&nbsp;', '', newsitem)
except:
newsitem = ''

return mark_safe(newsitem)

@register.tag()
def show_newsitem(parser, token):
try:
tag, identifier, field = token.split_contents()
except ValueError:
raise TemplateSyntaxError('%s needs newsitem number (x latest
newsitem) as an argument.' % tag)

return NewsItemBlockNode(identifier, field)


------


Looking at it again, I saw what was wrong and fixed it! For
completeness, I moved the NewsItem query within the NewsItemBlockNode
and everything works fine! The current code is:


import re

from django.template import Variable, VariableDoesNotExist, Node,
Library, Template, TemplateSynta
from django.conf import settings
from django.utils.safestring import mark_safe
from django.utils.html import escape
from django.utils.translation import ugettext as _

register = Library()

from cms.news.models import NewsItem
from django.db.models import Q
from datetime import datetime

class NewsItemBlockNode(Node):
def __init__(self, identifier, field):
self.identifier = str(identifier)
self.field = str(field)
self.image = False

def render(self, context):
try:
# newsitems = NewsItem.objects.all().order_by('-
created_at')
# newsitems = NewsItem.objects.visible().order_by('-
news_timestamp')
newsitems = NewsItem.objects.filter(Q(expires_at__gt =
datetime.now()) | Q(expires_at_
except:
newsitems = None

number = -1
numbers = {
'large': 0,
'large-small': 0,
'small1': 1,
'small2': 2,
'small3': 3,
'small4': 4,
'medium': 5,
}

# Only image
if self.field == 'teaser-image':
self.field = 'teaser'
self.image = True

if self.identifier in numbers:
number = numbers[self.identifier]

try:
newsitem = getattr(newsitems[number], self.field)

if type(newsitem).__name__ == 'datetime':
if self.identifier in ['medium', 'large']:
newsitem = newsitem.strftime('%d [%m] %Y')

newsitem = newsitem.replace('[01]', 'januari')
newsitem = newsitem.replace('[02]', 'februari')
newsitem = newsitem.replace('[03]', 'maart')
newsitem = newsitem.replace('[04]', 'april')
newsitem = newsitem.replace('[05]', 'mei')
newsitem = newsitem.replace('[06]', 'juni')
newsitem = newsitem.replace('[07]', 'juli')
newsitem = newsitem.replace('[08]', 'augustus')
newsitem = newsitem.replace('[09]', 'september')
newsitem = newsitem.replace('[10]', 'oktober')
newsitem = newsitem.replace('[11]', 'november')
newsitem = newsitem.replace('[12]', 'december')

newsitem = newsitem.upper()
else:
newsitem = newsitem.strftime('%d-%m-%Y')

if self.image:
# Filter only image
src = re.search('<img(.+)src="(.*?)"(.+)/>', newsitem)

if src and src.group(2):
newsitem = src.group(2)
else:
newsitem = '/media/site/img/blank.gif'
elif self.field == 'teaser':
# Filter image
newsitem = re.sub('<img (.+) />', '', newsitem)
newsitem = re.sub('<a.*?>', '', newsitem)
newsitem = re.sub('</a>', '', newsitem)
newsitem = re.sub('&nbsp;', '', newsitem)
except:
newsitem = ''

return mark_safe(newsitem)

@register.tag()
def show_newsitem(parser, token):
try:
tag, identifier, field = token.split_contents()
except ValueError:
raise TemplateSyntaxError('%s needs newsitem number (x latest
newsitem) as an argument.' %

return NewsItemBlockNode(identifier, field)


Thanks Michal and Daniel for your help!

Wim

On Jun 22, 8:24 pm, Daniel Roseman <dan...@roseman.org.uk> wrote:
> On Wednesday, 22 June 2011 14:32:10 UTC+1, Wim Feijen wrote:
>
> > Hello,
>
> > Atwww.mkb-rotterdam.nlwe use a template tag to display NewsItems in

bruno desthuilliers

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Jun 24, 2011, 6:53:01 AM6/24/11
to Django users
On Jun 24, 11:57 am, Wim Feijen <wimfei...@gmail.com> wrote:
>
> Looking at it again, I saw what was wrong and fixed it! For
> completeness, I moved the NewsItem query within the NewsItemBlockNode

FWIW, code at the module top-level is only executed when the module is
first imported. Now you'll know ;)

> and everything works fine! The current code is:
>
> import re
>
> from django.template import Variable, VariableDoesNotExist, Node,
> Library, Template, TemplateSynta
> from django.conf import settings
> from django.utils.safestring import mark_safe
> from django.utils.html import escape
> from django.utils.translation import ugettext as _
>
> register = Library()
>
> from cms.news.models import NewsItem
> from django.db.models import Q
> from datetime import datetime
>
> class NewsItemBlockNode(Node):
>     def __init__(self, identifier, field):
>         self.identifier = str(identifier)
>         self.field      = str(field)
>         self.image      = False
>
>     def render(self, context):
>         try:
>             newsitems = NewsItem.objects.filter(Q(expires_at__gt =
> datetime.now()) | Q(expires_at_
>         except:

Never use a bare except clause, unless you reraise the exception.

>             newsitems = None
>
>         number  = -1
>         numbers = {
>             'large':       0,
>             'large-small': 0,
>             'small1':      1,
>             'small2':      2,
>             'small3':      3,
>             'small4':      4,
>             'medium':      5,
>         }
>
>         # Only image
>         if self.field == 'teaser-image':
>             self.field = 'teaser'
>             self.image = True

Never change a Node's attributes from within the render method - this
will screw you sooner or later. Use local variables instead (with the
added bonus of improved performances - local variables are way faster
than attribute lookups).

>         if self.identifier in numbers:
>             number = numbers[self.identifier]
>
>         try:
>             newsitem = getattr(newsitems[number], self.field)
>
>             if type(newsitem).__name__ == 'datetime':

you may want to read about "isintance"

>                 if self.identifier in ['medium', 'large']:

use a tuple instead of a list - it's cheaper.

>                     newsitem = newsitem.strftime('%d [%m] %Y')
>
>                     newsitem = newsitem.replace('[01]', 'januari')
>                     newsitem = newsitem.replace('[02]', 'februari')
>                     newsitem = newsitem.replace('[03]', 'maart')
>                     newsitem = newsitem.replace('[04]', 'april')
>                     newsitem = newsitem.replace('[05]', 'mei')
>                     newsitem = newsitem.replace('[06]', 'juni')
>                     newsitem = newsitem.replace('[07]', 'juli')
>                     newsitem = newsitem.replace('[08]', 'augustus')
>                     newsitem = newsitem.replace('[09]', 'september')
>                     newsitem = newsitem.replace('[10]', 'oktober')
>                     newsitem = newsitem.replace('[11]', 'november')
>                     newsitem = newsitem.replace('[12]', 'december')

You may want to have a read at Django's and Python's localisation
features...

>                     newsitem = newsitem.upper()
>                 else:
>                     newsitem = newsitem.strftime('%d-%m-%Y')
>
>             if self.image:
>                 # Filter only image
>                 src = re.search('<img(.+)src="(.*?)"(.+)/>', newsitem)

regexps are not the safest way to parse html.

>                 if src and src.group(2):
>                     newsitem = src.group(2)
>                 else:
>                     newsitem = '/media/site/img/blank.gif'

Use named urls and reverse() instead - unless you are happy with
maintenance headache, of course ;)

>             elif self.field == 'teaser':
>                 # Filter image
>                 newsitem = re.sub('<img (.+) />', '', newsitem)
>                 newsitem = re.sub('<a.*?>', '', newsitem)
>                 newsitem = re.sub('</a>', '', newsitem)
>                 newsitem = re.sub('&nbsp;', '', newsitem)

Proverbial SquaredWheel alert. Django (and Python) have safer ways to
strip a text from HTML tags and entities.

>         except:

Same as above. Exceptions and traceback are here to HELP you fixing
your code, so don't shoot yourself in the foot by silently passing
them.


HTH

Wim Feijen

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Jun 24, 2011, 10:02:34 AM6/24/11
to Django users
Thanks Bruno for your detailed advice and attention!

I agree wholeheartedly.

Wim

On Jun 24, 12:53 pm, bruno desthuilliers
<bruno.desthuilli...@gmail.com> wrote:

bruno desthuilliers

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Jun 24, 2011, 10:51:47 AM6/24/11
to Django users


On Jun 24, 4:02 pm, Wim Feijen <wimfei...@gmail.com> wrote:
> Thanks Bruno for your detailed advice and attention!
>

Sorry I didn't have time to provide relevant pointers (which I usually
do) :-/
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