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How to limit the number of responses to my for loop to 3 in Django Templates?

In my current Django template I have two models in use, which are defined in my views.py as:
'tasks' : IndividualTask.objects.all(),
'updates' : TaskUpdate.objects.all(),
I have set up signals so that when there is an update to a task, an update is created.
Currently, I iterate through each task, then each of their updates and pull out the relevant updates for each task, as shown below.
{% for task in tasks %}
{% for update in updates %}
{% if task.id == update.task.id %}
{{ update.update }}
{% endif %}
{% endfor %}
{% endfor %}
However, I would like to limit the number of updates I show to three.
I have tried using slice, show below, but this limits all updates to the top 3 of all updates as opposed to the top 3 of each individual task's updates.
{% for task in tasks %}
{% for update in updates|slice:":3" %}
{% if task.id == update.task.id %}
{{ update.update }}
{% endif %}
{% endfor %}
{% endfor %}
Models.py is as below:
class IndividualTask(models.Model):
task = models.CharField(
max_length = 256,
blank=False,
null=True,
)
task_description = models.CharField(
max_length = 256,
blank=False,
null=True,
)
expected_completion = models.DateField(
max_length = 64,
null=True,
)
goal = models.ForeignKey(
IndividualGoal,
on_delete=models.CASCADE,
related_name="goals",
blank=False,
null=True,
)
creator = models.ForeignKey(
User,
on_delete=models.CASCADE,
related_name="creator",
blank=False,
null=True,
)
owner = models.ForeignKey(
User,
on_delete=models.CASCADE,
blank=False,
null=True,
)
status_choices = [
("", "Select Current Status"),
("Preparation", "Preparation"),
("Review", "Review"),
("Update", "Update"),
("Finalised", "Finalised"),
]
current_status = models.CharField(
max_length=32,
choices = status_choices,
default = "Select current status",
)
created = models.DateField(
auto_now_add = True,
)
def __str__(self):
return f"{self.task}"
class TaskUpdate(models.Model):
update = models.CharField(
max_length = 5000,
)
task = models.ForeignKey(
IndividualTask,
on_delete=models.CASCADE,
null = True,
)
update_created = models.DateField(
auto_now_add = True,
)
update_time_created = models.TimeField(
auto_now_add = True,
)
author = models.ForeignKey(
User,
on_delete=models.CASCADE,
related_name="update_author",
blank=True,
null=True,
)
update_choices = [
("New Task", "New Task"),
("New Commentary", "New Commentary"),
]
update_status = models.CharField(
max_length=32,
choices = update_choices,
null = True,
)
class Meta:
ordering = ["-update_created", "-update_time_created"]
I would be grateful for any advice as to how I can limit the number of updates shown for each task to 3 please?
EDIT:
Full traceback shown below:
Environment:
Request Method: GET
Request URL: http://127.0.0.1:8000/tasks/
Django Version: 4.0.2
Python Version: 3.9.10
Installed Applications:
['tasks.apps.TasksConfig',
'notes',
'accounts',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles']
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 /Users/Tom/Desktop/squeasy/tasks/templates/tasks/tasks.html, error at line 69
'RelatedManager' object is not iterable
59 : Expected Completion Date
60 : </div>
61 : <div class = expected_completion>
62 : {{ task.expected_completion }}
63 : </div>
64 : </div>
65 : </div>
66 : <div class = task_sub_header>
67 : Latest updates:
68 : </div>
69 : {% for update in task.taskupdate_set|slice:":3" %}
70 : {% if task.id == update.task.id %}
71 : <div class = individual_update>
72 : {% if update.update_status == "New Task" %}
73 : {{ update.author }} created this task on {{ update.update_created|date:"l jS F" }} at {{ update.update_time_created|time:"H:i" }}
74 : {% elif update.update_status == "New Commentary" %}
75 : {{ update.author }} updated the commentary for {{ update.task }} on {{ update.update_created|date:"l jS F" }} at {{ update.update_time_created|time:"H:i" }}
76 : {% endif %}
77 : </div>
78 : {% endif %}
79 : {% endfor %}
Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/django/core/handlers/exception.py", line 47, in inner
response = get_response(request)
File "/usr/local/lib/python3.9/site-packages/django/core/handlers/base.py", line 181, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/Users/Tom/Desktop/squeasy/tasks/views.py", line 28, in tasks
return render(request, "tasks/tasks.html", context)
File "/usr/local/lib/python3.9/site-packages/django/shortcuts.py", line 19, in render
content = loader.render_to_string(template_name, context, request, using=using)
File "/usr/local/lib/python3.9/site-packages/django/template/loader.py", line 62, in render_to_string
return template.render(context, request)
File "/usr/local/lib/python3.9/site-packages/django/template/backends/django.py", line 61, in render
return self.template.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 176, in render
return self._render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 168, in _render
return self.nodelist.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 977, in render
return SafeString(''.join([
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 978, in <listcomp>
node.render_annotated(context) for node in self
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/loader_tags.py", line 153, in render
return compiled_parent._render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 168, in _render
return self.nodelist.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 977, in render
return SafeString(''.join([
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 978, in <listcomp>
node.render_annotated(context) for node in self
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/loader_tags.py", line 65, in render
result = block.nodelist.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 977, in render
return SafeString(''.join([
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 978, in <listcomp>
node.render_annotated(context) for node in self
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/defaulttags.py", line 298, in render
return nodelist.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 977, in render
return SafeString(''.join([
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 978, in <listcomp>
node.render_annotated(context) for node in self
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/defaulttags.py", line 217, in render
nodelist.append(node.render_annotated(context))
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/defaulttags.py", line 217, in render
nodelist.append(node.render_annotated(context))
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/defaulttags.py", line 298, in render
return nodelist.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 977, in render
return SafeString(''.join([
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 978, in <listcomp>
node.render_annotated(context) for node in self
File "/usr/local/lib/python3.9/site-packages/django/template/base.py", line 938, in render_annotated
return self.render(context)
File "/usr/local/lib/python3.9/site-packages/django/template/defaulttags.py", line 173, in render
values = list(values)
Exception Type: TypeError at /tasks/
Exception Value: 'RelatedManager' object is not iterable

In the context you can pass the IndividualTasks with the TaskUpdates ordered in descending order with a Prefetch object [Django-doc]:
from django.db.models import Prefetch
context = {
'tasks' : IndividualTask.objects.prefetch_related(
Prefetch('taskupdate_set', TaskUpdate.objects.order_by('-update_created', '-update_time_created'))
)
}
then in the template you enumerate over the taskupdate_set:
{% for task in tasks %}
{% for update in task.taskupdate_set.all|slice:":3" %}
{{ update.update }}
{% endfor %}
{%endfor %}
Note: It is normally better to make use of the settings.AUTH_USER_MODEL [Django-doc] to refer to the user model, than to use the User model [Django-doc] directly. For more information you can see the referencing the User model section of the documentation.

Fixing No Reverse Match in a Django Project

I am getting the following error: Reverse for 'order_pdf' with arguments '('',)' not found. 1 pattern(s) tried: ['business_plan/(?P<id>[0-9]+)/pdf/$']
I am not sure exactly what is the reason for it.
Here is the model:
class Info(models.Model):
logo = models.ImageField(default='report-cover.jpg', null=True, blank=True)
date_posted = models.DateTimeField(default=timezone.now)
name = models.CharField(null=True, blank=True, max_length=100)
Here is the views.py
def add_business_plan(request):
# info=Info.objects.all()
if request.method == 'POST':
# create a form instance and populate it with data from the request:
form = infoForm(request.POST)
# check whether it's valid:
if form.is_valid():
form.save()
business_name = form.cleaned_data.get('businessName')
messages.success(request, f'PDF created for {business_name}!')
# return redirect('businessplan:businessplan')
# redirect(reverse('businessplan:businessplan', kwargs={'successful_submit': True}))
return render(request, 'businessplan/businessplan.html', {'successful_submit': True})
# if a GET (or any other method) we'll create a blank form
else:
form = infoForm()
print(form.errors)
return render(request, 'businessplan/businessplan.html', {'form': form, 'successful_submit': False,
# "Info": info
})
def order_pdf(request, info_id):
info = get_object_or_404(Info, id=info_id)
html = render_to_string('businessplan/pdf.html', {'info': info})
response = HttpResponse(content_type='application/pdf')
response['Content-Disposition'] = 'attachment; filename="{}-Business Plan.pdf"'.format(info.businessName)
weasyprint.HTML(string=html, base_url=request.build_absolute_uri()).write_pdf(response,
stylesheets=[weasyprint.CSS(settings.STATICFILES_DIRS[0] + '\css\\report.css')], presentational_hints=True)
return response
def admin_order_pdf(request, info_id):
info = get_object_or_404(Info, id=info_id)
html = render_to_string('businessplan/pdf.html', {'info': info})
response = HttpResponse(content_type='application/pdf')
response['Content-Disposition'] = 'filename="{}-Business Plan.pdf"'.format(info.businessName)
weasyprint.HTML(string=html, base_url=request.build_absolute_uri()).write_pdf(response,
stylesheets=[weasyprint.CSS(settings.STATICFILES_DIRS[0] + '\css\\report.css')], presentational_hints=True)
return response
Here is the urls.py
urlpatterns = [
path('', add_business_plan, name='businessplan'),
path('businessplan/admin/info/<str:info_id>/pdf/', admin_order_pdf, name='admin_order_pdf'),
#path('<str:info_id>/pdf/', admin_order_pdf, name='admin_order_pdf'),
path('<str:info_id>/pdf/', order_pdf, name='order_pdf'),
]
Here is the businessplan.html snippet of the template:
....modal divs
<a href="{% url 'businessplan:order_pdf' Info.id %}">
<!--<a href="{% url 'businessplan:order_pdf' obj.id %}">-->
<!--<a href="{% url 'businessplan:order_pdf' Info.info_id %}">-->
....modal divs
<form class="needs-validation" method="post" novalidate enctype="multipart/form-data">
{% csrf_token %}
<div class="form-outline mb-4 mt-3">
<input required autocomplete="off" type="text" class="form-control" name=" name"
{% if form.is_bound %} value= "{{ form.name.value }}" {% endif %}>
<label class="form-label">Name</label>
</div>
{% for err in form.name.errors %}
<small class="text-danger ml-2">{{ err }}</small>
{% endfor %}
</div>
</form>
{% if successful_submit %}
<script type="text/javascript">
$(document).ready(function(){
$("#exampleModal").modal('show');
});
</script>
{% endif %}
I can access the pdf from the admin but I am trying to access to add this button for easier functionality.
I have tried changing the info_id to id it didn't work.
What is the reason for this error?
Here is the traceback:
Internal Server Error: /business_plan/
Traceback (most recent call last):
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
response = get_response(request)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\core\handlers\base.py", line 179, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\User\Desktop\Portfolio\businessplan\views.py", line 30, in add_business_plan
return render(request, 'businessplan/businessplan.html', {'form': form, 'successful_submit': False })
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\shortcuts.py", line 19, in render
content = loader.render_to_string(template_name, context, request, using=using)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\loader.py", line 62, in render_to_string
return template.render(context, request)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\backends\django.py", line 61, in render
return self.template.render(context)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\base.py", line 170, in render
return self._render(context)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\base.py", line 162, in _render
return self.nodelist.render(context)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\base.py", line 938, in render
bit = node.render_annotated(context)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\base.py", line 905, in render_annotated
return self.render(context)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\template\defaulttags.py", line 446, in render
url = reverse(view_name, args=args, kwargs=kwargs, current_app=current_app)
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\urls\base.py", line 87, in reverse
return iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs))
File "C:\Users\User\Desktop\Portfolio\venv\lib\site-packages\django\urls\resolvers.py", line 685, in _reverse_with_prefix
raise NoReverseMatch(msg)
django.urls.exceptions.NoReverseMatch: Reverse for 'order_pdf' with arguments '('',)' not found. 1 pattern(s) tried: ['business_plan/(?P<info_id>[^/]+)/pdf/$']
[10/Oct/2021 06:58:51] "GET /business_plan/ HTTP/1.1" 500 143694

Looks like <a href="{% url 'businessplan:order_pdf' Info.id %}"> doesn't work because you don't pass it to the template context.
As a result, the call fails because Info.id is an empty string (cf https://docs.djangoproject.com/en/3.2/ref/templates/api/#invalid-template-variables), hence breaking the URL reversing logic.
You should pass your info instance to the template context to make this work, e.g like this:
return render(
request,
'businessplan/businessplan.html',
{
'form': form,
'successful_submit': False,
"Info": info_instance
}
)

NoReverseMatch at /job_category/IT/

Reverse for 'job_category' with keyword arguments '{'id': <Category: Government>}' not found. 1 pattern(s) tried: ['job_category/(?P<category_slug>[^/]+)/$']
{% extends 'base1.html' %}
{% block content %}
<div class="left col-sm-4" style="float:left; width: 360px;">
<h6 class="p-2" style="background:#A9CCE3; color:#2F4F4F;">JOB CATEGORIES</h6>
<ul class="list-group">
{% for x in categories %}
<li class="list-group-item c1 list-group-item-action" style="color: rgb(2,96,170);">
<div class="p-2">
<h7 class="card-title">
{{x.name}}
</h7>
</div>
<div class="overlay1"></div>
</li>
{% endfor %}
</ul>
</div>
<div class="right col-sm-8" style="float: right; width:825px;">
<!--{% if category %}{{category.name}}{% endif %} !-->
<div class="row container-fluid">
{% for job in jobs %}
<div class="col-sm-3 mt-3">
<div class="card c1">
<div class="overlay1"></div>
<div class="card-body">
<h5 class="card-title" style="color: rgb(2,96,170);">
{{job.post}}</h5>
<h6 class="card-text" style="color: rgb(85, 85, 85);">
{{job.job_id.comp_name}}</h6>
<p><i class="fas fa-map-marker-alt mr-1"></i>{{job.address}}<i
class="far fa-calendar-alt ml-3 mr-1"></i>{{job.todate|date:'d M, Y'}}</p>
<a href="{% url 'job_detail' job.job_id.id %}" class="btn btn-primary btn-sm right"
style="position:relative; float:right;">View more</a>
</div>
</div>
</div>
{% endfor %}
</div>
</div>
{% endblock content %}
views.py:
def job_category(request, category_slug=None):
category = None
job_requirements = []
categories = Category.objects.all()
jobs = Job.objects.all()
if category_slug:
category = Category.objects.get(slug=category_slug)
print(category.slug)
jobs = Job.objects.filter(job_category=category.slug)
for job in jobs:
job_requirements.append(JobRequirements.objects.get(job_id=job))
return render(request, 'JobCategory/category.html', {'categories': categories,
'jobs': job_requirements})
urls.py:
path('job_category/<str:category_slug>/', views.job_category, name='job_category'),
Models.py:
class Category(models.Model):
name = models.CharField(max_length=40, blank=True, null=True)
slug = models.CharField(max_length=4, unique=True)
def __str__(self):
return self.name
def get_absolute_path(self):
return reverse('job_category', kwargs={'category_slug': self.slug})
I've been trying to filter my page category wise. I cannot find where my mistake is at and can't simply decode this error message. I'm very new to this. Please help!
(Update) Traceback:
Internal Server Error: /job_category/IT/
Traceback (most recent call last):
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
response = get_response(request)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\core\handlers\base.py", line 115, in _get_response
response = self.process_exception_by_middleware(e, request)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\core\handlers\base.py", line 113, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "C:\Users\DELL\PycharmProjects\RECRUIT\Home\views.py", line 33, in job_category
'jobs': job_requirements})
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\shortcuts.py", line 19, in render
content = loader.render_to_string(template_name, context, request, using=using)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\loader.py", line 62, in render_to_string
return template.render(context, request)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\backends\django.py", line 61, in render
return self.template.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 171, in render
return self._render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 163, in _render
return self.nodelist.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 936, in render
bit = node.render_annotated(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 903, in render_annotated
return self.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\loader_tags.py", line 150, in render
return compiled_parent._render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 163, in _render
return self.nodelist.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 936, in render
bit = node.render_annotated(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 903, in render_annotated
return self.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\loader_tags.py", line 62, in render
result = block.nodelist.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 936, in render
bit = node.render_annotated(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\base.py", line 903, in render_annotated
return self.render(context)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\template\defaulttags.py", line 443, in render
url = reverse(view_name, args=args, kwargs=kwargs, current_app=current_app)
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\urls\base.py", line 87, in reverse
return iri_to_uri(resolver._reverse_with_prefix(view, prefix, *args, **kwargs))
File "C:\Users\DELL\Anaconda3\lib\site-packages\django\urls\resolvers.py", line 677, in _reverse_with_prefix
raise NoReverseMatch(msg)
django.urls.exceptions.NoReverseMatch: Reverse for 'job_category' with keyword arguments '{'id': <Category: Government>}' not found. 1 pattern(s) tried: ['
job_category/(?P<category_slug>[^/]+)/$']
[14/Dec/2020 11:08:58] "GET /job_category/IT/ HTTP/1.1" 500 173336

I solved this problem by replacing my kwargs 'category_slug' with 'id'. But, I have no clue why it didn't take category_slug as an kwargs.
class Category(models.Model):
name = models.CharField(max_length=40, blank=True, null=True)
slug = models.CharField(max_length=4, unique=True)
def __str__(self):
return self.name
def get_absolute_path(self):
return reverse('job_category', kwargs={'id': self.slug})
urls.py
path('job_category/<str:id>/', views.job_category, name='job_category')
views.py
def job_category(request, id=None):
category = None
job_requirements = []
categories = Category.objects.all()
jobs = Job.objects.all()
if id:
category = Category.objects.get(slug=id)
print(category.slug)
jobs = Job.objects.filter(job_category=category.slug)
for job in jobs:
job_requirements.append(JobRequirements.objects.get(job_id=job))
print(job_requirements)
return render(request, 'JobCategory/category.html', {'categories': categories,
'jobs': job_requirements})

(Django) DetailView template not displaying information

Within my maintenance app, I have six models. I will include only 2 of the models that are relevant towards this question. There is a list of equipment (Listview) which displays properly. However, I'm having a problem creating a DetailView for each equipment. When I go to the http://127.0.0.1:8000/maintenance/equipments/1 it should display all equipment instance (details) relevant to equipment 1 but it displays back the equipment list page, i.e, http://127.0.0.1:8000/maintenance/equipments/.
models.py
from django.db import models
class Equipment(models.Model):
"""
Model representing an Equipment (but not a specific type of equipment).
"""
title = models.CharField(max_length=200)
physicist = models.ForeignKey('Physicist', null=True, help_text= 'add information about the physicist')
technician = models.ForeignKey('Technician', null=True, help_text= 'add information about the technician')
# Physicist as a string rather than object because it hasn't been declared yet in the file.
features = models.TextField(max_length=1000, help_text='Enter a brief description of the features of the equipment')
machine_number = models.CharField('Number', max_length=30, null=True, help_text='Enter the Equipment number')
specialty = models.ForeignKey(Specialty, null=True, help_text='Select a specialty for an equipment')
# Specialty class has already been defined so we can specify the object above.
assigned_technician = models.CharField(max_length=50, null= True, blank=True)
#This is for the Technician who the repair of the Equipment is assigned to.
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse('equipment-detail', args=[str(self.id)])
def display_specialty(self):
return ', '.join([ specialty.name for specialty in self.specialty.all()[:3] ])
display_specialty.short_description = 'Specialty'
class Meta:
ordering = ['-id']
class EquipmentInstance(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, help_text="Unique ID for this particular equipment across the entire database")
equipment = models.ForeignKey('Equipment', on_delete=models.SET_NULL, null=True)
imprint = models.CharField(max_length=200)
due_date = models.DateField(null=True, blank=True)
delegate = models.ForeignKey('Physicist', on_delete=models.SET_NULL, null=True, blank=True)
def is_overdue(self):
if self.due_date and date.today() > self.due_date:
return True
return False
MAINTENANCE_STATUS = (
('p', 'Past Maintenance'),
('o', 'On Maintenance'),
('a', 'Available'),
('r', 'Reserved'),
)
status = models.CharField(max_length=1, choices = MAINTENANCE_STATUS, blank=True, default='m', help_text='Equipment availability')
class Meta:
ordering = ["due_date"]
permissions = (("can_mark_maintained", "Set equipment as maintained"),)
def __str__(self):
"""
String for representing the Model object
"""
return '{0} ({1})'.format(self.id,self.equipment.title)
maintanance/urls.py
from django.conf.urls import url
from qatrack.maintenance import views
from qatrack.maintenance import models
urlpatterns = [
url(r'^$', views.MDashboard, name='m_dash'),
url(r'^equipments/$', views.EquipmentListView.as_view(), name='equipments'),
url(r'^equipment(?P<pk>\d+)/$', views.EquipmentDetailView.as_view(), name='equipment-detail'),
]
views.py
from django.shortcuts import render
from django.views.generic import DetailView, ListView
from qatrack.maintenance import models
class EquipmentListView(ListView):
template_name = 'maintenance/equipment_list.html'
def get_queryset(self):
return models.Equipment.objects.all()
paginate_by = 10
class EquipmentDetailView(DetailView):
model = models.Equipment
template_name = 'maintenance/equipment_detail.html'
context_object_name = 'equipment'
equipment_list.html
{% extends "maintenance/m_base.html" %}
{% block body %}
<div class="row">
<div class="col-md-12">
<div class="box">
<h1>Equipment List</h1>
{% if equipment_list %}
<ul>
{% for equipment in equipment_list %}
<li>
{{ equipment.title }} ({{equipment.physicist}}, {{equipment.technician}})
</li>
{% endfor %}
</ul>
{% else %}
<p>There are no equipments in the database.</p>
{% endif %}
</div>
</div>
</div>
{% endblock body %}
equipment_detail.html
{% extends "maintenance/m_base.html" %}
{% block title %}Equipment Details{% endblock %}
{% block body %}
<h1>Title: {{ equipment.title }}</h1>
<h2>Machine Detail</h2>
<p><strong>Physicist:</strong> {{ equipment.physicist }}</p> <!-- physicist detail link not yet defined -->
<p><strong>Technician:</strong> {{ equipment.technician }}</p> <!-- technician detail link not yet defined -->
<p><strong>Features:</strong> {{ equipment.features }}</p>
<p><strong>Machine_number:</strong> {{ equipment.machine_number }}</p>
<p><strong>Specialty:</strong> {% for specialty in equipment.specialty.all %} {{ specialty }}{% if not forloop.last %}, {% endif %}{% endfor %}</p>
{% for type in equipment.equipmentinstance_set.all %}
<hr>
<p class="{% if type.status == 'a' %}text-success{% elif type.status == 'm' %}text-danger{% else %}text-warning{% endif %}">{{ type.get_status_display }}</p>
{% if type.status != 'a' %}<p><strong>Due to be maintained:</strong> {{type.due_date}}</p>{% endif %}
<p><strong>Imprint:</strong> {{type.imprint}}</p>
<p class="text-muted"><strong>Id:</strong> {{type.id}}</p>
{% endfor %}
</div>
{% endblock body %}
urls.py
from django.conf import settings
from django.conf.urls import include, url
from django.conf.urls.static import static
from django.views.generic.base import TemplateView, RedirectView
from django.contrib.staticfiles.templatetags.staticfiles import static as static_url
from django.contrib import admin
from qatrack.maintenance.views import get_data
admin.autodiscover()
urlpatterns = [
url(r'^$', TemplateView.as_view(template_name="homepage.html"), name="home"),
url(r'^accounts/', include('qatrack.accounts.urls')),
url(r'^qa/', include('qatrack.qa.urls')),
url(r'^servicelog/', include('qatrack.service_log.urls')),
url(r'^parts/', include('qatrack.parts.urls')),
url(r'^units/', include('qatrack.units.urls')),
url(r'^issues/', include('qatrack.issue_tracker.urls')),
url(r'^maintenance/', include('qatrack.maintenance.urls')),
] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
I have gone through a lot of questions similar to this here and applied them but I still can't get the DetailView to work. I will really appreciate any help. Thanks. After making changes I encountered this traceback error
Internal Server Error: /maintenance/equipment1/ Traceback (most recent
call last): File
"/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/urls/base.py",
line 77, in reverse
extra, resolver = resolver.namespace_dict[ns] KeyError: 'equipments'
During handling of the above exception, another exception occurred:
Traceback (most recent call last): File
"/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/core/handlers/exception.py",
line 41, in inner
response = get_response(request) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/core/handlers/base.py",
line 217, in _get_response
response = self.process_exception_by_middleware(e, request) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/core/handlers/base.py",
line 215, in _get_response
response = response.render() File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/response.py",
line 107, in render
self.content = self.rendered_content File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/response.py",
line 84, in rendered_content
content = template.render(context, self._request) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/backends/django.py",
line 66, in render
return self.template.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 207, in render
return self._render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/test/utils.py",
line 107, in instrumented_test_render
return self.nodelist.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 990, in render
bit = node.render_annotated(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 957, in render_annotated
return self.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/loader_tags.py",
line 177, in render
return compiled_parent._render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/test/utils.py",
line 107, in instrumented_test_render
return self.nodelist.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 990, in render
bit = node.render_annotated(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 957, in render_annotated
return self.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/loader_tags.py",
line 177, in render
return compiled_parent._render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/test/utils.py",
line 107, in instrumented_test_render
return self.nodelist.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 990, in render
bit = node.render_annotated(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 957, in render_annotated
return self.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/loader_tags.py",
line 72, in render
result = block.nodelist.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 990, in render
bit = node.render_annotated(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 957, in render_annotated
return self.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/defaulttags.py",
line 322, in render
return nodelist.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 990, in render
bit = node.render_annotated(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/base.py",
line 957, in render_annotated
return self.render(context) File "/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/template/defaulttags.py",
line 458, in render
url = reverse(view_name, args=args, kwargs=kwargs, current_app=current_app) File
"/home/blesjoe1/venvs/qatrack3/lib/python3.5/site-packages/django/urls/base.py",
line 87, in reverse
raise NoReverseMatch("%s is not a registered namespace" % key) django.urls.exceptions.NoReverseMatch: 'equipments' is not a
registered namespace [14/May/2018 16:05:33] "GET
/maintenance/equipment1/ HTTP/1.1" 500 215728

Your url is not correct
instead of
url(r'^equipment(?:/(?P<pk>\d+))?/$', views.EquipmentDetailView.as_view(), name="equipment_detail"),
it should be:
url(r'^equipment/(?P<pk>\d+)/$', views.EquipmentDetailView.as_view(), name="equipment_detail"),

Update your DetailView with this:
class EquipmentDetailView(DetailView):
model = models.Equipment
template_name = 'maintenance/equipment_detail.html'
context_object_name = 'equipment'
You don't need to override default method if you are not doing anything extra than the DetailView offers.

Recursion Error - Maximum Recursion dept exceeded when ForeignKey('self') django

I am getting an error in admin console while trying to open a model (employees in my case). This is occurring after adding a field which is a ForeignKey('self'). I guess it is conflicting with str method. If I comment out the method, there is no error, but all the objects in the model are appearing as 'employee object'. Here is what my error looks like https://ibb.co/jHt84Q
Here is my models.py:
from django.db import models
import calendar
from datetime import datetime
from datetime import timedelta
class employees(models.Model):
emp_id=models.PositiveIntegerField()
emp_name = models.CharField(max_length = 100)
emp_lname = models.CharField(max_length = 100)
emp_loc = models.CharField(max_length = 100,null=True)
manager_id=models.ForeignKey('self',null=True,blank=True)
image=models.ImageField(upload_to='profile_image',default='/profile_image/profile-icon.png')
email = models.EmailField(default='app-engine#gmail.com', blank=False)
def __str__(self):
return str(self.emp_id) + '-' + self.emp_name + '-' + self.emp_loc+'-'+str(self.manager_id)
class leave(models.Model):
employee = models.ForeignKey(employees, on_delete=models.CASCADE, default='1')
start_date = models.DateField()
end_date = models.DateField()
status=models.CharField(max_length=1,default='P')
ltype=models.CharField(max_length=2)
message=models.CharField(max_length=500,blank=True)
date_created = models.DateTimeField(auto_now_add=True)
def leave_length(self):
return self.end_date - self.start_date+timedelta(days=1);
def __str__(self):
return str(self.id) + '/' + str(self.employee.emp_name) +'/'+str(self.start_date) +'/'+str(self.end_date) +'/'+str(self.status)+'/'+str(self.date_created)
Here is my traceback:
Environment:
Request Method: GET
Request URL: http://localhost:8000/admin/apply/employees/
Django Version: 1.11.3
Python Version: 3.6.0
Installed Applications:
['apply.apps.ApplyConfig',
'm_manage',
'pending.apps.PendingConfig',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles']
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 C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\templates\admin\base.html, error at line 75
maximum recursion depth exceeded while calling a Python object 65 : <li{% if message.tags %} class="{{ message.tags }}"{% endif %}>{{ message|capfirst }}</li>
66 : {% endfor %}</ul>
67 : {% endif %}
68 : {% endblock messages %}
69 :
70 : <!-- Content -->
71 : <div id="content" class="{% block coltype %}colM{% endblock %}">
72 : {% block pretitle %}{% endblock %}
73 : {% block content_title %}{% if title %}<h1>{{ title }}</h1>{% endif %}{% endblock %}
74 : {% block content %}
75 : {% block object -tools %}{% endblock %}
76 : {{ content }}
77 : {% endblock %}
78 : {% block sidebar %}{% endblock %}
79 : <br class="clear" />
80 : </div>
81 : <!-- END Content -->
82 :
83 : {% block footer %}<div id="footer"></div>{% endblock %}
84 : </div>
85 : <!-- END Container -->
Traceback:
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\db\models\options.py" in get_field
617. return self.fields_map[field_name]
During handling of the above exception ('__str__'), another exception occurred:
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\utils.py" in lookup_field
283. f = _get_non_gfk_field(opts, name)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\utils.py" in _get_non_gfk_field
317. field = opts.get_field(name)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\db\models\options.py" in get_field
619. raise FieldDoesNotExist("%s has no field named '%s'" % (self.object_name, field_name))
During handling of the above exception (employees has no field named '__str__'), another exception occurred:
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\db\models\fields\related_descriptors.py" in __get__
178. rel_obj = getattr(instance, self.cache_name)
During handling of the above exception ('employees' object has no attribute '_manager_id_cache'), another exception occurred:
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\core\handlers\exception.py" in inner
41. response = get_response(request)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\core\handlers\base.py" in _get_response
217. response = self.process_exception_by_middleware(e, request)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\core\handlers\base.py" in _get_response
215. response = response.render()
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\response.py" in render
107. self.content = self.rendered_content
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\response.py" in rendered_content
84. content = template.render(context, self._request)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\backends\django.py" in render
66. return self.template.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render
207. return self._render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in _render
199. return self.nodelist.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render
990. bit = node.render_annotated(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render_annotated
957. return self.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\loader_tags.py" in render
177. return compiled_parent._render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in _render
199. return self.nodelist.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render
990. bit = node.render_annotated(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render_annotated
957. return self.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\loader_tags.py" in render
177. return compiled_parent._render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in _render
199. return self.nodelist.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render
990. bit = node.render_annotated(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render_annotated
957. return self.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\loader_tags.py" in render
72. result = block.nodelist.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render
990. bit = node.render_annotated(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render_annotated
957. return self.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\loader_tags.py" in render
72. result = block.nodelist.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render
990. bit = node.render_annotated(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\base.py" in render_annotated
957. return self.render(context)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\template\library.py" in render
225. _dict = self.func(*resolved_args, **resolved_kwargs)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\templatetags\admin_list.py" in result_list
340. 'results': list(results(cl))}
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\templatetags\admin_list.py" in results
316. yield ResultList(None, items_for_result(cl, res, None))
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\templatetags\admin_list.py" in __init__
307. super(ResultList, self).__init__(*items)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\templatetags\admin_list.py" in items_for_result
218. f, attr, value = lookup_field(field_name, result, cl.model_admin)
File "C:\Users\rhshanka\AppData\Local\Programs\Python\Python36\lib\site-packages\django-1.11.3-py3.6.egg\django\contrib\admin\utils.py" in lookup_field
299. value = attr()
File "C:\Users\rhshanka\LMS\apply\models.py" in __str__
15. return str(self.emp_id) + '-' + self.emp_name + '-' + self.emp_loc+'-'+str(self.manager_id)
Exception Type: RecursionError at /admin/apply/employees/
Exception Value: maximum recursion depth exceeded while calling a Python object

Try it:
def __str__(self):
self_str = '%s-%s-%s' % (self.emp_id, self.emp_name, self.emp_loc)
if self.manager_id and self.manager_id.pk != self.pk:
return '%s-%s' % (self_str, str(self.manager_id))
return self_str
And you need to be sure your logic is correct, for many inherits it will be not readable.