{"title":"文件上传","version":"2.2","locale":"zh-hans","docname":"topics/http/file-uploads","url":"/zh-hans/2.2/topics/http/file-uploads/","canonical":"https://djangodocs.dev/zh-hans/2.2/topics/http/file-uploads/","summary":"Django处理文件上传时, 文件最终会位于:attr:request.FILES (想了解更多关于``request`` 对象的信息请阅读 request and response…","html":"

文件上传Link to this heading#

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Django处理文件上传时, 文件最终会位于:attr:request.FILES <django.http.HttpRequest.FILES> (想了解更多关于``request`` 对象的信息请阅读 request and response objects 1) 。本文档主要介绍文件是如何存储在硬盘和内存中的，以及如何定制默认行为。

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简单文件上传Link to this heading#

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考虑使用一个简单的表单，表单中包含一个:class:`~django.forms.FileField`字段:

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forms.py
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Python
from django import forms\n\nclass UploadFileForm(forms.Form):\n    title = forms.CharField(max_length=50)\n    file = forms.FileField()\n
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处理这个表单的视图将通过:attr:request.FILES <django.http.HttpRequest.FILES>`获取到文件数据, attr:`request.FILES <django.http.HttpRequest.FILES>`是包含了表单中每个 :class:`~django.forms.FileField (还有 ImageField, 以及其他:class:~django.forms.FileField 的子类)键值的字典 。所以 `数据可以通过`request.FILES['file']``获取到。

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请注意只有在请求是通过 POST 提交且提交的 <form> 表单有 enctype="multipart/form-data" 属性的时候，request.FILES 才会包含文件数据，否则的话， request.FILES 是空的。

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绝大多数的情况下，你只需要像 binding-uploaded-files`中所述将文件数据从``request` 传入给 表单，示例如下：

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views.py
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Python
from django.http import HttpResponseRedirect\nfrom django.shortcuts import render\nfrom .forms import UploadFileForm\n\n# Imaginary function to handle an uploaded file.\nfrom somewhere import handle_uploaded_file\n\ndef upload_file(request):\n    if request.method == 'POST':\n        form = UploadFileForm(request.POST, request.FILES)\n        if form.is_valid():\n            handle_uploaded_file(request.FILES['file'])\n            return HttpResponseRedirect('/success/url/')\n    else:\n        form = UploadFileForm()\n    return render(request, 'upload.html', {'form': form})\n
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注意我们必须将 request.FILES 传入到表单的\n构造方法中，只有这样文件数据才能绑定到表单中。

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我们通常可能像这样处理上传文件：

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Code
def handle_uploaded_file(f):\n    with open('some/file/name.txt', 'wb+') as destination:\n        for chunk in f.chunks():\n            destination.write(chunk)\n
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使用 UploadedFile.chunks() 而不是 read() 是为了确保即使是大文件又不会将我们系统的内存占满。

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There are a few other methods and attributes available on UploadedFile\nobjects; see UploadedFile for a complete reference.

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通过模型来处理上传的文件Link to this heading#

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如果想要在 FileField 上的 Model 保存文件，使用 ModelForm 会让这一过程变得简单。当调用 form.save() 时，文件对象将会被保存在对相应 FileField 的 upload_to 参数所指定的地方：

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Code
from django.http import HttpResponseRedirect\nfrom django.shortcuts import render\nfrom .forms import ModelFormWithFileField\n\ndef upload_file(request):\n    if request.method == 'POST':\n        form = ModelFormWithFileField(request.POST, request.FILES)\n        if form.is_valid():\n            # file is saved\n            form.save()\n            return HttpResponseRedirect('/success/url/')\n    else:\n        form = ModelFormWithFileField()\n    return render(request, 'upload.html', {'form': form})\n
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如果你准备手工构建对象，你可以指定来自 request.FILES 的文件对象到模型里的文件对象：

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Code
from django.http import HttpResponseRedirect\nfrom django.shortcuts import render\nfrom .forms import UploadFileForm\nfrom .models import ModelWithFileField\n\ndef upload_file(request):\n    if request.method == 'POST':\n        form = UploadFileForm(request.POST, request.FILES)\n        if form.is_valid():\n            instance = ModelWithFileField(file_field=request.FILES['file'])\n            instance.save()\n            return HttpResponseRedirect('/success/url/')\n    else:\n        form = UploadFileForm()\n    return render(request, 'upload.html', {'form': form})\n
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上传多个文件Link to this heading#

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如果你想使用一个表单字段上传多个文件，则需要设置字段的 widget 的 multiple HTML 属性。

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forms.py
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Python
from django import forms\n\nclass FileFieldForm(forms.Form):\n    file_field = forms.FileField(widget=forms.ClearableFileInput(attrs={'multiple': True}))\n
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然后覆盖 FormView 子类的 post 方法来控制多个文件上传：

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views.py
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Python
from django.views.generic.edit import FormView\nfrom .forms import FileFieldForm\n\nclass FileFieldView(FormView):\n    form_class = FileFieldForm\n    template_name = 'upload.html'  # Replace with your template.\n    success_url = '...'  # Replace with your URL or reverse().\n\n    def post(self, request, *args, **kwargs):\n        form_class = self.get_form_class()\n        form = self.get_form(form_class)\n        files = request.FILES.getlist('file_field')\n        if form.is_valid():\n            for f in files:\n                ...  # Do something with each file.\n            return self.form_valid(form)\n        else:\n            return self.form_invalid(form)\n
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上传 HandlersLink to this heading#

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当一个用户上传文件时，Django 会把文件数据传递给 upload handler —— 这是一个很小的类，它用来在上传时处理文件数据。上传处理模块最初定义在 FILE_UPLOAD_HANDLERS 里，默认为：

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Code
["django.core.files.uploadhandler.MemoryFileUploadHandler",\n "django.core.files.uploadhandler.TemporaryFileUploadHandler"]\n
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MemoryFileUploadHandler 和 TemporaryFileUploadHandler 提供 Django 默认文件上传行为，小文件读入内存，大文件存在磁盘上。

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你可以编写自定义的 handlers 来自定义 Django 如何处理文件。比如，你可以使用自定义的 handlers 来强制处理用户层面的配额，动态压缩数据，渲染进度条，甚至可以将数据发送到其他存储地址而不是本地。查看 Writing custom upload handlers 来了解你如何自定义或者完全替换上传行为。

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上传数据的存储Link to this heading#

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在保存上传的文件之前，数据需要保存到某处。

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默认情况下，如果上传的文件小于2.5兆，Django 将把文件的所有内容保存到内存里。这意味着保存文件只涉及从内存中读取和写入磁盘，因此这很快。

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但如果上传的文件很大，Django 会把文件写入系统临时目录的临时文件里存储。在类 Unix 平台里这意味着 Django 会生成一个类似名为 /tmp/tmpzfp6I6.upload 的文件。如果上传的文件非常大，你可以查看这个文件的大小增长，因为 Django 将数据流式传输到磁盘上。

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2.5 megabytes; /tmp; 等这些细节只是合理的默认值，在下一节要介绍它们如何被自定义。

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改变上传处理行为Link to this heading#

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这里有一些控制 Django 文件上传行为的配置，请查看 File Upload Settings 。

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动态修改上传处理程序Link to this heading#

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有时候某些视图需要不同的上传行为。在这些例子里，你可以基于每个请求覆盖上传处理程序。默认情况下，这个列表将包含由 FILE_UPLOAD_HANDLERS 设置的上传处理程序，但你可以像修改其他列表一样修改这个列表。

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比如，假设你正在编写 ProgressBarUploadHandler ，来提供在上传过程中的反馈给 Ajax widget。你需要添加这个处理程序到你的上传处理模块：

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Code
request.upload_handlers.insert(0, ProgressBarUploadHandler(request))\n
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你或许想在这里使用 list.insert() （而不是 append() ），因为进度条处理程序需要在其他处理程序之前使用。记住，上传处理程序是按顺序处理的。

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如果你想完全替换上传处理程序，你只需要指定新列表：

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Code
request.upload_handlers = [ProgressBarUploadHandler(request)]\n
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