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Posted September 10, 2018 9:55am by

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?

September 10, 2018 10:35am

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

September 11, 2018 4:20am

This line works:

        form_class = forms.TrueFalseQuestionForm
        question = question.truefalsequestion

But multiplechoicequestion does not. Strange...

3 Answers

September 11, 2018 6:24am

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
>>>

September 11, 2018 4:15am

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

September 11, 2018 4:20am

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

September 11, 2018 4:22am

From models.py

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


class TrueOrFalseQuestion(Question):
    pass

September 11, 2018 4:33am

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

September 11, 2018 4:40am

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

September 11, 2018 4:40am

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})

September 11, 2018 4:41am

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 %}

September 11, 2018 4:41am

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

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Christopher Gunawan

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Receiving error when trying to edit question

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

3 Answers

Stuart McIntosh

Stuart McIntosh

Stuart McIntosh

Stuart McIntosh

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Stuart McIntosh

Stuart McIntosh

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan

Christopher Gunawan