文件或图片一般通过表单进行。用户在前端点击文件上传，然后以POST方式将数据和文件提交到服务器。服务器在接收到POST请求后需要将其存储在服务器上的某个地方。Django默认的存储地址是相对于根目录的/media/文件夹，存储的默认文件名就是文件本来的名字。上传的文件如果不大于2.5MB，会先存入服务器内存中，然后再写入磁盘。如果上传的文件很大，Django会把文件先存入临时文件，再写入磁盘。
Django默认处理方式会出现一个问题，所有文件都存储在一个文件夹里。不同用户上传的有相同名字的文件可能会相互覆盖。另外用户还可能上传一些不安全的文件如js和exe文件，我们必需对允许上传文件的类型进行限制。因此我们在利用Django处理文件上传时必需考虑如下3个因素:
注意：以上事项对于上传图片是同样适用的。
Django文件上传一般有3种方式(如下所示)。我们会针对3种方式分别提供代码示范。
Ajax文件上传部分见Django与Ajax交互篇。
我们先使用django-admin startproject命令创建一个叫file_project的项目，然后cd进入file_project, 使用python manage.py startapp创建一个叫file_upload的app。
我们首先需要将file_upload这个app加入到我们项目里，然后设置/media/和/STATIC_URL/文件夹。我们上传的文件都会放在/media/文件夹里。我们还需要使用css和js这些静态文件，所以需要设置STATIC_URL。
#file_project/settings.py
INSTALLED_APPS = [
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'file_upload',# 新增
]
STATIC_URL = '/static/'
STATICFILES_DIRS = [os.path.join(BASE_DIR, "static"), ]
MEDIA_ROOT = os.path.join(BASE_DIR, 'media')
MEDIA_URL = '/media/'
#file_project/urls.py
from django.contrib import admin
from django.urls import path, include
from django.conf import settings
from django.conf.urls.static import static
urlpatterns = [
path('admin/', admin.site.urls),
path('file/', include("file_upload.urls")),
] + static(settings.MEDIA_URL, document_root=settings.MEDIA_ROOT)
使用Django上传文件创建模型不是必需，然而如果我们需要对上传文件进行系统化管理，模型还是很重要的。我们的File模型包括file和upload_method两个字段。我们通过upload_to选项指定了文件上传后存储的地址，并对上传的文件名进行了重命名。
#file_upload/models.py
from django.db import models
import os
import uuid
# Create your models here.
# Define user directory path
def user_directory_path(instance, filename):
ext = filename.split('.')[-1]
filename = '{}.{}'.format(uuid.uuid4().hex[:10], ext)
return os.path.join("files", filename)
class File(models.Model):
file = models.FileField(upload_to=user_directory_path, null=True)
upload_method = models.CharField(max_length=20, verbose_name="Upload Method")
注意：如果你不使用ModelForm，你还需要手动编写代码存储上传文件。
本项目一共包括3个urls, 分别对应普通表单上传，ModelForm上传和显示文件清单。
#file_upload/urls.py
from django.urls import re_path, path
from . import views
# namespace
app_name = "file_upload"
urlpatterns = [
# Upload File Without Using Model Form
re_path(r'^upload1/$', views.file_upload, name='file_upload'),
# Upload Files Using Model Form
re_path(r'^upload2/$', views.model_form_upload, name='model_form_upload'),
# View File List
path('file/', views.file_list, name='file_list'),
]
我们先定义一个一般表单FileUploadForm，并通过clean方法对用户上传的文件进行验证，如果上传的文件名不以jpg, pdf或xlsx结尾，将显示表单验证错误信息。关于表单的自定义和验证更多内容见Django基础: 表单forms的设计与使用。
#file_upload/forms.py
from django import forms
from .models import File
# Regular form
class FileUploadForm(forms.Form):
file = forms.FileField(widget=forms.ClearableFileInput(attrs={'class': 'form-control'}))
upload_method = forms.CharField(label="Upload Method", max_length=20,
widget=forms.TextInput(attrs={'class': 'form-control'}))
def clean_file(self):
file = self.cleaned_data['file']
ext = file.name.split('.')[-1].lower()
if ext not in ["jpg", "pdf", "xlsx"]:
raise forms.ValidationError("Only jpg, pdf and xlsx files are allowed.")
# return cleaned data is very important.
return file
注意： 使用clean方法对表单字段进行验证时，别忘了return验证过的数据，即cleaned_data。只有返回了cleaned_data, 视图中才可以使用form.cleaned_data.get(‘xxx')获取验证过的数据。
对应一般文件上传的视图file_upload方法如下所示。当用户的请求方法为POST时，我们通过form.cleaned_data.get('file')获取通过验证的文件，并调用自定义的handle_uploaded_file方法来对文件进行重命名，写入文件。如果用户的请求方法不为POST，则渲染一个空的FileUploadForm在upload_form.html里。我们还定义了一个file_list方法来显示文件清单。
#file_upload/views.py
from django.shortcuts import render, redirect
from .models import File
from .forms import FileUploadForm, FileUploadModelForm
import os
import uuid
from django.http import JsonResponse
from django.template.defaultfilters import filesizeformat
# Create your views here.
# Show file list
def file_list(request):
files = File.objects.all().order_by("-id")
return render(request, 'file_upload/file_list.html', {'files': files})
# Regular file upload without using ModelForm
def file_upload(request):
if request.method == "POST":
form = FileUploadForm(request.POST, request.FILES)
if form.is_valid():
# get cleaned data
upload_method = form.cleaned_data.get("upload_method")
raw_file = form.cleaned_data.get("file")
new_file = File()
new_file.file = handle_uploaded_file(raw_file)
new_file.upload_method = upload_method
new_file.save()
return redirect("/file/")
else:
form = FileUploadForm()
return render(request, 'file_upload/upload_form.html',
{'form': form, 'heading': 'Upload files with Regular Form'}
)
def handle_uploaded_file(file):
ext = file.name.split('.')[-1]
file_name = '{}.{}'.format(uuid.uuid4().hex[:10], ext)
# file path relative to 'media' folder
file_path = os.path.join('files', file_name)
absolute_file_path = os.path.join('media', 'files', file_name)
directory = os.path.dirname(absolute_file_path)
if not os.path.exists(directory):
os.makedirs(directory)
with open(absolute_file_path, 'wb+') as destination:
for chunk in file.chunks():
destination.write(chunk)
return file_path
注意：
上传表单模板upload_form.html代码如下:
#file_upload/templates/upload_form.html
{% extends "file_upload/base.html" %}
{% block content %}
{% if heading %}
h3>{{ heading }}/h3>
{% endif %}
form action="" method="post" enctype="multipart/form-data" >
{% csrf_token %}
{{ form.as_p }}
button class="btn btn-info form-control " type="submit" value="submit">Upload/button>
/form>
{% endblock %}
显示文件清单模板file_list.html代码如下所示:
# file_upload/templates/file_list.html
{% extends "file_upload/base.html" %}
{% block content %}
h3>File List/h3>
p> a href="/file/upload1/" rel="external nofollow" >RegularFormUpload/a> | a href="/file/upload2/" rel="external nofollow" >ModelFormUpload/a>
| a href="/file/upload3/" rel="external nofollow" >AjaxUpload/a>/p>
{% if files %}
table class="table table-striped">
tbody>
tr>
td>Filename URL/td>
td>Filesize/td>
td>Upload Method/td>
/tr>
{% for file in files %}
tr>
td>a href="{{ file.file.url }}" rel="external nofollow" >{{ file.file.url }}/a>/td>
td>{{ file.file.size | filesizeformat }}/td>
td>{{ file.upload_method }}/td>
/tr>
{% endfor %}
/tbody>
/table>
{% else %}
p>No files uploaded yet. Please click a href="{% url 'file_upload:file_upload' %}" rel="external nofollow" >here/a>
to upload files./p>
{% endif %}
{% endblock %}
注意：
使用ModelForm上传是小编我推荐的上传方式，前提是你已经在模型中通过upload_to选项自定义了用户上传文件存储地址，并对文件进行了重命名。我们首先要自定义自己的FileUploadModelForm，由File模型重建的。代码如下所示:
#file_upload/forms.py
from django import forms
from .models import File
# Model form
class FileUploadModelForm(forms.ModelForm):
class Meta:
model = File
fields = ('file', 'upload_method',)
widgets = {
'upload_method': forms.TextInput(attrs={'class': 'form-control'}),
'file': forms.ClearableFileInput(attrs={'class': 'form-control'}),
}
def clean_file(self):
file = self.cleaned_data['file']
ext = file.name.split('.')[-1].lower()
if ext not in ["jpg", "pdf", "xlsx"]:
raise forms.ValidationError("Only jpg, pdf and xlsx files are allowed.")
# return cleaned data is very important.
return file
使用ModelForm处理文件上传的视图model_form_upload方法非常简单，只需调用form.save()即可，无需再手动编写代码写入文件。
#file_upload/views.py
from django.shortcuts import render, redirect
from .models import File
from .forms import FileUploadForm, FileUploadModelForm
import os
import uuid
from django.http import JsonResponse
from django.template.defaultfilters import filesizeformat
# Create your views here.
# Upload File with ModelForm
def model_form_upload(request):
if request.method == "POST":
form = FileUploadModelForm(request.POST, request.FILES)
if form.is_valid():
form.save() # 一句话足以
return redirect("/file/")
else:
form = FileUploadModelForm()
return render(request, 'file_upload/upload_form.html',
{'form': form,'heading': 'Upload files with ModelForm'}
)
模板跟前面一样，这里就不展示了。
https://github.com/shiyunbo/django-file-upload-download
本文提供并解读了利用Django上传文件的3种主要方式(一般表单上传，ModelForm上传和Ajax上传)及示范代码。
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