Sneak some advanced logic into a Django template
I was adding on an app to a Django project at work where I was overriding an existing template but did not have access to the view that called that template. I was left in a scenario where I had the variables that the view was originally set up with, but non of the new models that I had added.
In a filter you can do whatever logic you want, and then pass information back to the view. Please keep in mind, this is probably a horrible practice, but it does have its uses. In this specific scenario I needed to query the new models without modifying the existing view, solution: add a filter and do the querying there.
This is the filter that I used to do the querying:
from django import template
from stager.jira.models import JiraProject, ProjectLink
from stager.staging.models import *
register = template.Library()
def has_jira(value, arg):
client = Client.objects.get(path=value)
project = client.projects.get(path=arg)
try:
jiras = ProjectLink.objects.get(ClientProject=project).JiraProject.exclude(filter_id='')
return True
except:
return False
register.filter('has_jira', has_jira)
Then, in my template:
{% load has_jira %}
{% if client.path|has_jira:project.path %}
A more general example if this would be to work around the annoyance of not being able to have multiple tests in an if statement in a template: You can’t do {% if this and that %}
A solution would be:
def if_and(value, arg):
if value and arg:
return True
else:
return False
def if_or(value, arg):
if value or arg:
return True
else:
return False
{% if True|if_and:False %}
show
{% else %}
don't show
{% endif %}
Let me know your thoughts, pros/cons of this method.
Ai’s stager project is open source and can be found at github
