急救，大老板们指点~
运行的时候直接报错，The view bookstore.views.update_book didn't return an HttpResponse object. It returned None instead.
**尝试按照网上的方案去修改缩进量，但是无效。__**
```python
def update_book(request, book_id):
try:
book = Book.objects.get(id=book_id, is_active=True)
except Exception as e:
print('update book error is %s' % e)
return HttpResponse('book is not existed')
if request == 'GET':
return render(request, 'bookstore/update_book.html', locals())
elif request == 'POST':
market_price = request.POST['market_price']
price = request.POST['price']
book.price = price
book.market_price = market_price
book.save()
return HttpResponseRedirect('/bookstore/all_book')
template 里面的html 如下：
```html
html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>update booktitle>
head>
<body>
<form action="/bookstore/update_book/{{ book.id }}" method="POST">
<p>
title <input type="text" value="{{ book.title }}" disabled="disabled">
p>
<P>
pub <input type="text" value="{{ book.pub }}" disabled="disabled" >
P>
<p>
price <input type="text" name="price" value="{{ book.price }}">
p>
<p>
market_price <input type="text" name="market_price" value="{{ book.market_price }}" >
p>
<p>
<input type="submit" value="renew">
p>
form>
body>
html>
The view bookstore.views.update_book didn't return an HttpResponse object. It returned None instead.
Request Method: GET
Request URL: http://127.0.0.1:8000/bookstore/update_book/1
Django Version: 4.1.7
Exception Type: ValueError
Exception Value:
The view bookstore.views.update_book didn't return an HttpResponse object. It returned None instead.
Exception Location: D:\JNU\mysite\venv\Lib\site-packages\django\core\handlers\base.py, line 332, in check_response
Raised during: bookstore.views.update_book
Python Executable: D:\JNU\mysite\venv\Scripts\python.exe
Python Version: 3.11.2
参考GPT和自己的思路：根据你提供的代码，可以看出在函数中有一个代码块缺少返回HttpResponse的语句，导致视图在某些情况下没有返回任何响应。具体来说，update_book函数中的第一个if request == 'GET'条件块中没有将HttpResponse对象返回，所以当请求为GET时会返回None。
要修复这个问题，只需在该条件块中添加一个HttpResponse对象返回即可。下面是修改后的代码示例：
def update_book(request, book_id):
try:
book = Book.objects.get(id=book_id, is_active=True)
except Exception as e:
print('update book error is %s' % e)
return HttpResponse('book is not existed')
if request.method == 'GET':
return render(request, 'bookstore/update_book.html', locals())
elif request.method == 'POST':
market_price = request.POST['market_price']
price = request.POST['price']
book.price = price
book.market_price = market_price
book.save()
return HttpResponseRedirect('/bookstore/all_book')
注意，我还在第一个条件块中修正了if request == 'GET'为if request.method == 'GET' ，因为你需要比较请求的方法类型而不是它的值。
希望这可以帮助您解决问题。