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Python

Christopher Gunawan
Christopher Gunawan
10,754 Points

Receiving error when trying to edit question

Receiving this error when trying to edit question:

RelatedObjectDoesNotExist at /courses/1/edit_question/1

Question has no multiplechoicequestion.

@login_required
def edit_question(request, quiz_pk, question_pk):
    question = get_object_or_404(models.Question, pk=question_pk, quiz_id=quiz_pk)
    if hasattr(question, 'truefalsequestion'):
        form_class = forms.TrueFalseQuestionForm
        question = question.truefalsequestion
    else:
        form_class = forms.MultipleChoiceQuestionForm
        question = question.multiplechoicequestion

    form = form_class(instance=question)

    if request.method == 'POST':
        form = form_class(request.POST, instance=question)
        if form.is_valid():
            form.save()
            messages.success(request, "Updated question")
            return HttpResponseRedirect(question.quiz.get_absolute_url())
    return render(request, 'courses/question_form.html', {'form': form,
                                                         'quiz': question.quiz})

What am I doing wrong?

Christopher Gunawan
Christopher Gunawan
10,754 Points

I have followed along with Kenneth and I'm not sure why my code does not work.

Christopher Gunawan
Christopher Gunawan
10,754 Points

This line works:

        form_class = forms.TrueFalseQuestionForm
        question = question.truefalsequestion

But multiplechoicequestion does not. Strange...

3 Answers

Hi there, I have downloaded the final version of the code from the video resource and the issue is that there is only 1 question with an ID of 2 in the database where the query is asking for a question with an ID of 4. To be honest I am unsure if this project has been fully completed.

You can test this out in the shell by doing the following

>>> from courses.models import Question
>>> question = Question.objects.get(pk=4) # this is the question_pk passed in via the URL (request)
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/Users/stuartmcintosh/Code/Python/treehouse_projects/social_team_builder/venv/lib/python3.6/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/stuartmcintosh/Code/Python/treehouse_projects/social_team_builder/venv/lib/python3.6/site-packages/django/db/models/query.py", line 379, in get
    self.model._meta.object_name
courses.models.DoesNotExist: Question matching query does not exist.
>>> question = Question.objects.all()
>>> question
<QuerySet [<Question: What all characters can be in a string?>]>
>>> question.count()
1
>>> question[0].id
2
>>>

Hi there this a related filed issue. The model Question has a no related TrueFalseQuestion with the Question that you are looking at 1.

Christopher Gunawan
Christopher Gunawan
10,754 Points

But TrueFalseQuestion inherits from Question, so there is a relation. Is there something else I am missing?

Christopher Gunawan
Christopher Gunawan
10,754 Points

From models.py

class MultipleChoiceQuestion(Question):
    shuffle_answers = models.BooleanField(default=False)


class TrueOrFalseQuestion(Question):
    pass

Hi there, can you point me to the code and I will have a look...

Christopher Gunawan
Christopher Gunawan
10,754 Points

from models.py

class Question(models.Model):
    quiz = models.ForeignKey(Quiz, on_delete=models.CASCADE)
    order = models.IntegerField(default=0)
    prompt = models.TextField()

    class Meta:
        ordering = ['order', ]

    def get_absolute_url(self):
        return self.quiz.get_absolute_url()

    def __str__(self):
        return self.prompt


class MultipleChoiceQuestion(Question):
    shuffle_answers = models.BooleanField(default=False)


class TrueOrFalseQuestion(Question):
    pass
Christopher Gunawan
Christopher Gunawan
10,754 Points

from views.py

@login_required
def edit_question(request, quiz_pk, question_pk):
    question = get_object_or_404(models.Question, pk=question_pk, quiz_id=quiz_pk)
    if hasattr(question, 'truefalsequestion'):
        form_class = forms.TrueFalseQuestionForm
        question = question.truefalsequestion
    else:
        form_class = forms.MultipleChoiceQuestionForm
        # TODO Fix this
        question = question.multiplechoicequestion

    form = form_class(instance=question)
    answer_forms = forms.AnswerInlineFormSet(
        queryset=form.instance.answer_set.all()
        )

    if request.method == 'POST':
        form = form_class(request.POST, instance=question)
        answer_forms = forms.AnswerInlineFormSet(
            request.POST, queryset=form.instance.answer_set.all()
            )
        if form.is_valid() and answer_forms.is_valid():
            form.save()
            answers = answer_forms.save(commit=False)
            for answer in answers:
                answer.question = question
                answer.save()
            for answer in answer_forms.deleted_objects:
                answer.delete()
            messages.success(request, "Updated question")
            return HttpResponseRedirect(question.quiz.get_absolute_url())
    return render(request, 'courses/question_form.html', {'form': form, 'quiz': question.quiz, 'formset': answer_forms})
Christopher Gunawan
Christopher Gunawan
10,754 Points

from question_form.html

{% extends "courses/layout.html" %}
{% load course_extras %}

{% block title %}{{ form.instance.prompt|default:"New question" }} | {{ quiz.course.title }}
{{ block.super }} {% endblock %}

{% block breadcrumbs %}
    <li><a href="{% url 'courses:detail' pk=quiz.course.pk %}">{{ quiz.course.title }}</a></li>
    <li><a href="{% url 'courses:quiz' course_pk=quiz.course.pk step_pk=quiz.pk %}">{{ quiz.title }}
    </a></li>
{% endblock %}

{% block content %}
    <div class="row columns">
        {{ block.super }}
        <h1>{{ form.instance.prompt|default:"Make a new question" }}</h1>
        <form method="POST" action="">
            {% csrf_token %}
            {{ form.as_p }}

            {{ formset.management_form }}

            <table role="grid" class="stack hover" style="width:100%">
                <thead>
                <tr>
                    <th scope="col" class="text-center" style="width: 10%">Order</th>
                    <th scope="col" class="text-center">Text</th>
                    <th scope="col" class="text-center" style="width: 10%">Correct</th>
                    <th scope="col" class="text-center" style="width: 10%">Delete?</th>
                </tr>
                </thead>
                <tbody class="order">
                    {% for form in formset %}
                        <tr class="answer-form {% if form.instance.pk %}item{% else %}new{% endif %}">
                            <td>{{ form.id }} {{ form.order }}</td>
                            <td>{{ form.text }}</td>
                            <td class="text-center">{{ form.correct }}</td>
                        {% if form.instance.pk %}
                            <td class="text-center">{{ form.DELETE }}</td>
                        {% else %}
                            <td class="text-center"></td>
                        {% endif %}
                        </tr>
                    {% endfor %}
                </tbody>
            </table>
            <input type="submit" class="button" value="Save">
        </form>
    </div>
{% endblock %}

{% block css %}
    {{ form.media.css }}
{% endblock %}

{% block javascript %}
    {% load static from staticfiles %}
    {{ form.media.js }}
    <script src="{% static 'js/vendor/jquery.formset.js' %}"></script><script>
        $('.answer-form').formset({addText: 'add answer', deleteText: 'remove'});
    </script>
{% endblock %}
Christopher Gunawan
Christopher Gunawan
10,754 Points

The error response:

RelatedObjectDoesNotExist at /courses/1/edit_question/4

Question has no multiplechoicequestion.

Request Method:     GET
Request URL:    http://127.0.0.1:8000/courses/1/edit_question/4
Django Version:     2.1.1
Exception Type:     RelatedObjectDoesNotExist
Exception Value:    

Question has no multiplechoicequestion.

Exception Location:     C:\Users\user\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\fields\related_descriptors.py in __get__, line 414
Python Executable:  C:\Users\user\AppData\Local\Programs\Python\Python37\python.exe
Python Version:     3.7.0
Python Path:    

['C:\\Users\\user\\learning_site',
 'C:\\Users\\user\\learning_site',
 'C:\\Users\\user\\AppData\\Local\\Programs\\Python\\Python37\\python37.zip',
 'C:\\Users\\user\\AppData\\Local\\Programs\\Python\\Python37\\DLLs',
 'C:\\Users\\user\\AppData\\Local\\Programs\\Python\\Python37\\lib',
 'C:\\Users\\user\\AppData\\Local\\Programs\\Python\\Python37',
 'C:\\Users\\user\\AppData\\Local\\Programs\\Python\\Python37\\lib\\site-packages',
 'C:\\Program Files\\JetBrains\\PyCharm '
 '2018.2.3\\helpers\\pycharm_matplotlib_backend']

Server time:    Tue, 11 Sep 2018 11:41:19 +0700