Reverse Iterating over Foreign Key - django

Question

I am trying the tutorial for Django on making a local library website with books.
One of the challenges is to make an author detail view which lists all the books that author has written. I am having trouble displaying any book information for the author.
Model.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.db import models
from django.urls import reverse
import uuid
# Create your models here.
class Genre(models.Model):
"""
Model resprenting the book genre
"""
name=models.CharField(max_length=200, help_text="Enter a book genre")
def __str__(self):
return self.name
class Book(models.Model):
title = models.CharField(max_length=200)
author = models.ForeignKey('Author', on_delete=models.SET_NULL, null=True)
summary = models.TextField(max_length=1000, help_text="Enter a brief description")
isbn = models.CharField('ISBN', max_length=13, help_text="13 character ISBN field")
genre = models.ManyToManyField(Genre, help_text="Select a genre for this book")
def __str__(self):
return self.title
def get_absolute_url(self):
return reverse('book-detail', args=[str(self.id)])
def display_genre(self):
return ', '.join([genre.name for genre in self.genre.all()[:3] ])
display_genre.short_description = 'Genre'
class BookInstance(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, help_text="Unique book number")
book = models.ForeignKey('Book', on_delete=models.SET_NULL, null=True)
imprint = models.CharField(max_length=200)
due_back = models.DateField(null=True, blank=True)
LOAN_STATUS = (
('d', 'Maintenance'),
('o', 'On loan'),
('a', 'Available'),
('r', 'Reserved'),
)
status = models.CharField(max_length=1, choices=LOAN_STATUS, blank=True, default='d', help_text="Book Availability")
class Meta:
ordering = ['due_back']
def __str__(self):
return ('%s (%s)' %(self.id, self.book.title))
class Author(models.Model):
first_name = models.CharField(max_length=100)
last_name = models.CharField(max_length=100)
date_of_birth = models.CharField(max_length=10, null=True, blank=True)
date_of_death = models.CharField(max_length=10, null=True, blank=True)
def get_absolute_url(self):
return reverse('author-detail', args=[str(self.id)])
def __str__(self):
return ('%s, %s' % (self.last_name, self.first_name))
def display_books(self):
books = Book.objects.get(pk=self.id)
return books.book_set.all()
display_books.short_description = 'Books'
author_detail.html
Really lost here!
{% extends "base.html" %}
{% block content %}
<h1>Author: {{ author }}</h1>
<p><strong>Date of Birth:</strong> {{ author.date_of_birth }}</p>
<p><strong>Date of Death:</strong> {{ author.date_of_death }}</p>
<!--<p><strong>Books:</strong> {% for books in book.author.pk.all %} {{ book.author }}{% if not forloop.last %}, {% endif %}{% endfor %}</p> -->
<div style="margin-left:20px;margin-top:20px">
<h4>Books</h4>
{% for books in book.all %}
<p>{{ books }} Testing Vars {{ book.author_set }} Get copies from key {{ book.author.pk }} </p>
{% endfor %}
</div>
{% endblock %}
Views.py
# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from django.shortcuts import render
from django.views import generic
# Create your views here.
from .models import Book, Author, BookInstance, Genre
def index(request):
num_books=Book.objects.all().count()
num_instances=BookInstance.objects.all().count()
#available books
num_instances_available=BookInstance.objects.filter(status__exact='a').count()
num_authors=Author.objects.count()
return render(request,
'index.html',
context={'num_books': num_books, 'num_instances': num_instances,
'num_instances_available' : num_instances_available, 'num_authors': num_authors},
)
class BookListView(generic.ListView):
model = Book
class BookDetailView(generic.DetailView):
model = Book
class AuthorListView(generic.ListView):
model = Author
class AuthorDetailView(generic.DetailView):
model = Author

Answer 1

Assuming author_detail.html is used in AuthorDetailView ListView, I'd suggest some changes in your template, maybe like this,
{% block content %}
<h1>Author: {{ object.first_name }} {{ object.last_name }}</h1>
<p><strong>Date of Birth:</strong> {{ object.date_of_birth }}</p>
<p><strong>Date of Death:</strong> {{ object.date_of_death }}</p>
<div style="margin-left:20px;margin-top:20px">
<h4>Books</h4>
{% for book in object.book_set.all %}
<p>{{ book.title }}</p>
{% endfor %}
</div>
{% endblock %}
Since, you haven't overridden the get_context_data() method of the ListView, the default context_variable_name would be object. You may need to refer the Author instance by object.