다음에 진행하면서 수정할려고 했는데 제대로 안되서 인지 답변만 달면 다음과 같은 에러가 나타납니다.
저와 비슷한 에러가 난 질문자가 있어 그 부분을 봤는데 저는 오타가 아니었습니다. 코드가 길어지니 찾기가
난망합니다.

IntegrityError at /pybo/answer/create/187/
NOT NULL constraint failed: pybo_answer.question_id
Request Method: POST
Request URL:    http://127.0.0.1:8000/pybo/answer/create/187/
Django Version: 3.1.3
Exception Type: IntegrityError
Exception Value:    
NOT NULL constraint failed: pybo_answer.question_id
Exception Location: F:\big7\django\jumptodjango\lib\site-packages\django\db\backends\sqlite3\base.py, line 413, in execute
Python Executable:  F:\big7\django\jumptodjango\Scripts\python.exe
Python Version: 3.8.5
Python Path:    
['F:\\big7\\django',
 'C:\\Users\\wonnh\\AppData\\Local\\Programs\\Python\\Python38\\python38.zip',
 'C:\\Users\\wonnh\\AppData\\Local\\Programs\\Python\\Python38\\DLLs',
 'C:\\Users\\wonnh\\AppData\\Local\\Programs\\Python\\Python38\\lib',
 'C:\\Users\\wonnh\\AppData\\Local\\Programs\\Python\\Python38',
 'F:\\big7\\django\\jumptodjango',
 'F:\\big7\\django\\jumptodjango\\lib\\site-packages']
Server time:    Thu, 11 Mar 2021 06:57:20 +0000

pybo/views.py

from django.shortcuts import render, get_object_or_404, redirect

from django.http import HttpResponse

from .models import Question
from django.utils import timezone
from .forms import QuestionForm,AnswerForm

from django.core.paginator import Paginator

def index(request):

    """
    pybo list

    question_list=Question.objects.order_by('-create_date')
    context={'question_list':question_list}

    """

    page=request.GET.get('page','1')


    question_list=Question.objects.order_by('-create_date')

    paginator=Paginator(question_list,10)
    page_obj=paginator.get_page(page)

   #context={'question_list':question_list}
    context={'question_list': page_obj}

    return render(request,'pybo/question_list.html',context)

def detail(request,question_id) :

    question = get_object_or_404(Question, pk=question_id)
    context={'question':question}
    return render(request,'pybo/question_detail.html', context)


def answer_create(request,question_id):
    """
    pybo answer list

    """

    question=get_object_or_404(Question, pk=question_id)
    question.answer_set.create(content=request.POST.get('content'),
                               create_date=timezone.now())
    return redirect('pybo:detail', question_id=question.id)
    #return redirect('pybo:detail',question_id=question.id)

def question_create(request):

    if request.method =='POST':
        form=QuestionForm(request.POST)
        if form.is_valid():
            question=form.save(commit=False)
            question.author=request.user
            question.create_date=timezone.now()
            question.save()

            return redirect('pybo:index')
    else:
        form=QuestionForm()
    context={'form':form}
    return render(request,'pybo/question_form.html', context)



def answer_create(request,question_id):
    question=get_object_or_404(Question, pk=question_id)

    if request.method =='POST':
        form=AnswerForm(request.POST)
        if form.is_valid():
            answer=form.save(commit=False)
            answer.create_date=timezone.now()
            answer.save()
            answer.author=request.user
            return redirect('pybo:detail',question_id=question.id)
    else:
        form=AnswerForm()
    context={'form':form,'question':question}
    return render(request,'pybo/question_detail.html', context)

pybo/urls.py

from django.urls import path
from . import views

app_name='pybo'  #namespace

urlpatterns=[
    path('', views.index, name='index'),
    path('<int:question_id>/', views.detail, name='detail'),
    path('answer/create/<int:question_id>/', views.answer_create, name='answer_create'),
    path('question/create/', views.question_create, name='question_create'),
]

#pybo/models.py
from django.db import models

from django.contrib.auth.models import User
# Create your models here.

class Question(models.Model):
    auther=models.ForeignKey(User,on_delete=models.CASCADE)
    subject=models.CharField(max_length=200)
    content=models.TextField()
    create_date=models.DateTimeField()

class Answer(models.Model):
    auther = models.ForeignKey(User, on_delete=models.CASCADE)
    question=models.ForeignKey(Question, on_delete=models.CASCADE)
    content=models.TextField()
    create_date=models.DateTimeField()

question_detail.html

{% extends 'base.html' %}
{% block content %}
<div class="container my-3">
    <h2 class="border-bottom py-2">{{ question.subject }}</h2>
    <div class="card my-3">
        <div class="card-body">
            <div class="card-text" style="white-space: pre-line;">{{ question.content }}</div>
            <div class="d-flex justify-content-end">
                <div class="badge badge-light p-2">
                    {{ question.create_date }}
                </div>
            </div>
        </div>
    </div>
    <h5 class="border-bottom my-3 py-2">{{question.answer_set.count}}개의 답변이 있습니다.</h5>
    {% for answer in question.answer_set.all %}
    <div class="card my-3">
        <div class="card-body">
            <div class="card-text" style="white-space: pre-line;">{{ answer.content }}</div>
            <div class="d-flex justify-content-end">
                <div class="badge badge-light p-2">
                    {{ answer.create_date }}
                </div>
            </div>
        </div>
    </div>
    {% endfor %}
    <form action="{% url 'pybo:answer_create' question.id %}" method="post" class="my-3">
        {% csrf_token %}
        {% if form.errors %}
        <div class="alert alert-danger" role="alert">
        {% for field in form %}
            {% if field.errors %}
            <strong>{{ field.label }}</strong>
            {{ field.errors }}
            {% endif %}
        {% endfor %}
        </div>

        {% endif %}
        <div class="form-group">
            <textarea name="content" id="content" class="form-control" rows="10"></textarea>
        </div>
        <input type="submit" value="답변등록" class="btn btn-primary">
    </form>
</div>
{% endblock %}

question_form.html

{% extends 'base.html' %}

{% block content %}
<div class="container">

    <h5 class="my-3 border-bottom pb-2">register question</h5>
    <form method="post" class="post-form my-3">
        {% csrf_token %}

<!--        오류 표시-->
        {% if form.errors %}
        <div class="alert alert-danger" role="alert">
            {% for field in form %}
            {% if filed.errors %}
            <strong>{{field.label}}</strong>
            {{field.errors}}
            {% endif %}
            {% endfor %}

        </div>
        {% endif %}
<!--        ends error-->

        <div class="form-group">
            <label for="subject">Title</label>
            <input type="text" class="form-control" name="subject" id="subject"
                   value="{{form.content.value|default_if_none:''}}">


        </div>

        <div class="form-group">
            <label for="content" >Content</label>
            <textarea class="form-control" name="content" id="content" row="10">
                {{form.content.value|default_if_none:''}}
            </textarea>
        </div>

<!--        {{form.as_p}}-->
        <button type="submit" class="btn btn-primary">Save</button>

    </form>
</div>
{% endblock %}