使 Django 中静态文件的浏览器缓存无效

Question

在 Django 中，我们有ManifestStaticFilesStorage用于缓存静态文件，但它在 Django 和浏览器之间工作，但我希望在用户和浏览器之间正确缓存。

我想要：每次更改静态文件时，都会重新计算文件的哈希值并且浏览器缓存无效，并且用户在没有运行--collectstatic --no-input情况下看到没有 F5 --collectstatic --no-input新静态文件。

我的代码现在不起作用： settings.py

STATICFILES_STORAGE = 'auth.utils.HashPathStaticFilesStorage'

CACHES = {
    'staticfiles': {
        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
        'LOCATION': 'staticfiles',
        'TIMEOUT': 3600 * 24 * 7,
        'MAX_ENTRIES': 100,
    }
}

和auth.utils.py ：

# -*- coding: utf-8 -*-

import time

from hashlib import sha384

from django.conf import settings
from django.core.cache import cache
from django.contrib.staticfiles.storage import ManifestStaticFilesStorage


try:
    ACCURACY = settings.STATICFILES_HASH_ACCURACY
except AttributeError:
    ACCURACY = 12

try:
    KEY_PREFIX = settings.STATICFILES_HASH_KEY_PREFIX
except AttributeError:
    KEY_PREFIX = 'staticfiles_hash'

class HashPathStaticFilesStorage(ManifestStaticFilesStorage):
    """A static file storage that returns a unique url based on the contents
    of the file. When a static file is changed the url will also change,
    forcing all browsers to download the new version of the file.

    The uniqueness of the url is a GET parameter added to the end of it. It
    contains the first 12 characters of the SHA3 sum of the contents of the
    file.

    Example: {% static "image.jpg" %} -> /static/image.jpg?4e1243

    The accuracy of the hash (number of characters used) can be set in
    settings.py with STATICFILES_HASH_ACCURACY. Setting this value too low
    (1 or 2) can cause different files to get the same hash and is not
    recommended. SHA3 hashes are 40 characters long so all accuracy values
    above 40 have the same effect as 40.

    The values can be cached for faster performance. All keys in the cache have
    the prefix specified in STATICFILES_HASH_KEY_PREFIX in setings.py. This
    value defaults to 'staticfiles_hash'
    """

    @property
    def prefix_key(self):
        return "%s:%s" % (KEY_PREFIX, 'prefix')

    def invalidate_cache(self, nocache=False):
        """Invalidates the cache. Run this when one or more static files change.
        If called with nocache=True the cache will not be used.
        """
        value = int(time.time())
        if nocache:
            value = None
        cache.set(self.prefix_key, value)

    def get_cache_key(self, name):
        hash_prefix = cache.get(self.prefix_key)
        if not hash_prefix:
            return None
        key = "%s:%s:%s" % (KEY_PREFIX, hash_prefix, name)
        return key

    def set_cached_hash(self, name, the_hash):
        key = self.get_cache_key(name)
        if key:
            cache.set(key, the_hash)

    def get_cached_hash(self, name):
        key = self.get_cache_key(name)
        if not key:
            return None
        the_hash = cache.get(key)
        return the_hash

    def calculate_hash(self, name):
        path = self.path(name)
        try:
            the_file = open(path, 'rb')
            the_hash = sha384(the_file.read()).hexdigest()[:ACCURACY]
            the_file.close()
        except IOError:
            return ""
        return the_hash

    def get_hash(self, name):
        the_hash = self.get_cached_hash(name)
        if the_hash:
            return the_hash
        the_hash = self.calculate_hash(name)
        self.set_cached_hash(name, the_hash)
        return the_hash

    def url(self, name):
        base_url = super(HashPathStaticFilesStorage, self).url(name)
        the_hash = self.get_hash(name)
        if "?" in base_url:
            return "%s&%s" % (base_url, the_hash)
        return "%s?%s" % (base_url, the_hash)

Answer 1

避免用户必须重新加载页面以获取新鲜静态内容的一种常见且简单的方法是在 HTML 标记中包含静态文件时附加一些可变值，如下所示：

<script src="{% static 'js/library.js' %}?{{ version }}"></script>

这样，当变量版本采用不同的值时，浏览器将被迫从服务器下载静态文件的新版本。

您可以使用自定义上下文处理器设置版本，例如从设置中读取项目版本。 像这样的东西：

from django.conf import settings

def version(request):
    return {
        'version': settings.VERSION
    }

如果您使用 git 作为 VCS，另一种方法是在将修改推送到服务器时将项目的最后一次提交哈希写入文件。 该文件应采用 Python 可读的格式。 这样就可以使用 git commit hash 作为前面提到的版本变量。 您可以使用 GIT post-receive hook执行此操作：

#!/bin/bash

WORKDIR=/path/to/project/
VERSION_MODULE=${WORKDIR}django_project/project/version.py

# for every branch which has been pushed
while read oldrev newrev ref
do
    # if branch pushed is master, update version.py file in the django project
    if [[ $ref =~ .*/master$ ]]; then
        GIT_WORK_TREE=$WORKDIR git checkout -f master
        echo "GIT_REF = 'master'" > $VERSION_MODULE
        echo "GIT_REV = '$newrev'" >> $VERSION_MODULE
    fi
done

那么你的上下文处理器可能是：

from project.version import GIT_REV

def version(request):
    return {
        'version': GIT_REV[:7]
    }

Answer 2

我只是使用这个非常简单的想法

<img src="{{ company.logo.url }}?v={% now 'U' %}" />

使用?v=强制版本并将版本设置为当前时间戳{% now 'U' %}这样它就会随着每个请求而改变