Python – Django: How to use a variable inside an if statement in the template

djangodjango-modelsdjango-templatespython

My views.py hands over a variable called "preSelect" that contains a Integer value.

Inside the template I want to use that Integer in an If statement to check if the current for loop counter is less equal or greater than than my value.

{% if forloop.counter <= {{ preSelect }} %}
    <td><input type="checkbox" name="checks" id="1" value={{ row.0 }} checked/></td>
{% else %}
   <td><input type="checkbox" name="checks" id="1" value={{ row.0 }} /></td>
{% endif %}

This however returns me the following error:

Environment:

Request Method: POST Request URL: http://127.0.0.1:8000/

Django Version: 1.10.2 Python Version: 2.7.11 Installed Applications:
['django.contrib.admin', 'django.contrib.auth',
'django.contrib.contenttypes', 'django.contrib.sessions',
'django.contrib.messages', 'django.contrib.staticfiles',
'testsetcreation'] Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']

Template error: In template
D:\Django\testsetcreation\templates\testsetcreation\testsetView.html,
error at line 61 Could not parse the remainder: '{{' from '{{' 51
: Comment 52 :
SW Version 53 : HW Version
54 : ABP 55 :
Project 56 : 57 :
58 : 59 : {% for row in
rows %} 60 : 61 : {%
if forloop.counter <= {{ preSelect }} %} 62 :
63 : {% else %} 64 :
65 : {% endif %} 66 :
{{ row.1 }} 67 : {{ row.2 }}
68 : 69 :
70 : {{
row.3 }} 71 :

Traceback:

File "c:\Python27\lib\site-packages\django\core\handlers\exception.py"
in inner
39. response = get_response(request)

File "c:\Python27\lib\site-packages\django\core\handlers\base.py" in
_get_response
187. response = self.process_exception_by_middleware(e, request)

File "c:\Python27\lib\site-packages\django\core\handlers\base.py" in
_get_response
185. response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "D:\Django\testsetcreation\views.py" in testsetView
102. return render(request, 'testsetcreation/testsetView.html', context)

File "c:\Python27\lib\site-packages\django\shortcuts.py" in render
30. content = loader.render_to_string(template_name, context, request, using=using)

File "c:\Python27\lib\site-packages\django\template\loader.py" in
render_to_string
67. template = get_template(template_name, using=using)

File "c:\Python27\lib\site-packages\django\template\loader.py" in
get_template
21. return engine.get_template(template_name)

File
"c:\Python27\lib\site-packages\django\template\backends\django.py" in
get_template
39. return Template(self.engine.get_template(template_name), self)

File "c:\Python27\lib\site-packages\django\template\engine.py" in
get_template
160. template, origin = self.find_template(template_name)

File "c:\Python27\lib\site-packages\django\template\engine.py" in
find_template
134. name, template_dirs=dirs, skip=skip,

File "c:\Python27\lib\site-packages\django\template\loaders\base.py"
in get_template
44. contents, origin, origin.template_name, self.engine,

File "c:\Python27\lib\site-packages\django\template\base.py" in
init
191. self.nodelist = self.compile_nodelist()

File "c:\Python27\lib\site-packages\django\template\base.py" in
compile_nodelist
233. return parser.parse()

File "c:\Python27\lib\site-packages\django\template\base.py" in parse
518. raise self.error(token, e)

Exception Type: TemplateSyntaxError at / Exception Value: Could not
parse the remainder: '{{' from '{{'

Best Answer

in Jinja, when you use the {%%} marks, don't put the variables inside {{}}

Example Code

{% if x > y %}
    # Do something
{% endif %}

So the code in your case would be

{% if forloop.counter <= preSelect %}
    # Do Something
{% endif %}

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Python – How to safely create a nested directory in Python

On Python ≥ 3.5, use pathlib.Path.mkdir:

from pathlib import Path
Path("/my/directory").mkdir(parents=True, exist_ok=True)

For older versions of Python, I see two answers with good qualities, each with a small flaw, so I will give my take on it:

Try os.path.exists, and consider os.makedirs for the creation.

import os
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Modern versions of Python improve this code quite a bit, both by exposing FileExistsError (in 3.3+)...

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...and by allowing a keyword argument to os.makedirs called exist_ok (in 3.2+).

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Python – How to get the current time in Python

Use:

>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2009, 1, 6, 15, 8, 24, 78915)

>>> print(datetime.datetime.now())
2009-01-06 15:08:24.789150

And just the time:

>>> datetime.datetime.now().time()
datetime.time(15, 8, 24, 78915)

>>> print(datetime.datetime.now().time())
15:08:24.789150

See the documentation for more information.

To save typing, you can import the datetime object from the datetime module:

>>> from datetime import datetime

Then remove the leading datetime. from all of the above.

Best Answer

Example Code

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