Can someone say where I did mistake?
I have 2 models: Project and Purpose.
class Purpose(models.Model):
code = models.UUIDField(_('Code'), primary_key=True, default=uuid.uuid4, editable=False)
project = models.ForeignKey(Project, on_delete=models.CASCADE)
text = models.TextField(_('Text'))
comments = models.ManyToManyField("Comment")
Every project has only one purpose. So in project_detail page I want to show purpose_add button only if that project dont have any other purpose object. Why I dont see button when there is no Purpose object with the same project_code?
views.py:
def project_detail(request, project_code):
***
purpose_is_not_exist = Purpose.objects.exclude(project=project_code).exists()
***
project_detail.html:
{% if purpose_is_not_exist %}
<button id="purpose-add-button"></button>
{% endif %}
{% if not purpose_is_not_exist %}
You should negate the False bool.
The confusion is caused by the variable name purpose_is_not_exist.
Purpose.objects.exclude(project=project_code).exists()
Above statement returns whether the Purpose object exists. You shall rename the variable to purpose_exists to avoid any confusion.
And, in the template when you want to add the button if it doesn't exist then negate the variable:
{% if not purpose_exists %}
Alternatively, if you would like to keep using the original name for the variable, then just negate in the view itself.
purpose_is_not_exist = not Purpose.objects.exclude(project=project_code).exists()