Django处理文件上传File Uploads

HttpRequest.FILES

表单上传的文件对象存储在类字典对象request.FILES中,表单格式需为multipart/form-data

request.FILES中的键来自于表单中的的name值:

img=request.FILES['image']

request.FILES中的值均为UploadedFile类文件对象。

UploadedFile

UploadedFile是类文件对象,具有以下方法和属性:

UploadedFile.read()

读取整个上传文件的数据,文件较大时慎用。

UploadedFile.multiple_chunks(chunk_size=None)

判断文件是否足够大,一般为2.5M

UploadedFile.chunks(chunk_size=None)

返回一个生成器对象,当multiple_chunks()为True时应该使用这个方法来代替read().

UploadedFile.name

上传文件的name。

UploadedFile.size

上传文件的大小。

UploadedFile.content_type

上传文件时的content_type报头,例如(e.g. text/plain or application/pdf). 

UpladedFile.charset

编码

存储文件

想将上传的文件存储在本地时:

f=request.FILES['image']
with open('some/file/name.txt', 'wb+') as destination:
    for chunk in f.chunks():
        destination.write(chunk)

使用Form处理上传文件

也可以使用django自带的form来处理上传文件。

先创建带FileFiled或者ImageFiled的Form:

# In forms.py...
from django import forms

class UploadFileForm(forms.Form):
    title = forms.CharField(max_length=50)
    file = forms.FileField()

用Form处理:

>>> f =UploadFileFormt(request.POST, request.FILES)

view函数:

from django.http import HttpResponseRedirect
from django.shortcuts import render_to_response
from .forms import UploadFileForm

def handle_uploaded_file(f):
    with open('some/file/name.txt', 'wb+') as destination:
        for chunk in f.chunks():
            destination.write(chunk)

def upload_file(request):
    if request.method == 'POST':
        form = UploadFileForm(request.POST, request.FILES)
        if form.is_valid():
            handle_uploaded_file(request.FILES['file'])
            return HttpResponseRedirect('/success/url/')
    else:
        form = UploadFileForm()
    return render_to_response('upload.html', {'form': form})

使用Model处理上传文件

如果创建了一个带FileField或者ImageField域的Model,需要将上传文件存储到Model的FileFIeld域。

比如,使用nicEdit文本编辑器时,需要存储上传的文件,建立Model:

from django.db import models

class NicEditImage(models.Model):
    image = models.ImageField(upload_to='nicedit/%Y/%m/%d')

创建ModelForm:

from django import forms

class NicEditImageForm(forms.ModelForm):
    class Meta:
        model = NicEditImage

view:

def upload(request):
    if not request.user.is_authenticated():
        json = simplejson.dumps({
            'success': False,
            'errors': {'__all__': 'Authentication required'}})
        return HttpResponse(json, mimetype='application/json')
    form = NicEditImageForm(request.POST or None, request.FILES or None)
    if form.is_valid():
        image = form.save()    #保存Form和Model
        json = simplejson.dumps({
            'success': True,
            'upload': {
                'links': {
                    'original': image.image.url},
                'image': {
                    'width': image.image.width,
                    'height': image.image.height}
            }
        })
    else:
        json = simplejson.dumps({
            'success': False, 'errors': form.errors})
    return HttpResponse(json, mimetype='application/json')

当然也可以手动存储文件到Model的文件域:

from django.http import HttpResponseRedirect
from django.shortcuts import render
from .forms import UploadFileForm
from .models import ModelWithFileField

def upload_file(request):
    if request.method == 'POST':
        form = UploadFileForm(request.POST, request.FILES)
        if form.is_valid():
            instance = ModelWithFileField(file_field=request.FILES['file'])   #保存文件到FileField域
            instance.save()
            return HttpResponseRedirect('/success/url/')
    else:
        form = UploadFileForm()
    return render(request, 'upload.html', {'form': form})

不使用Form处理

想获得更大自由度时,可以全手动处理。

from django.db import models

class Car(models.Model):
    name = models.CharField(max_length=255)
    price = models.DecimalField(max_digits=5, decimal_places=2)
    photo = models.ImageField(upload_to='cars')

Model的FileField有以下属性:

>>> car = Car.objects.get(name="57 Chevy")
>>> car.photo

>>> car.photo.name
u'cars/chevy.jpg'
>>> car.photo.path
u'/media/cars/chevy.jpg'
>>> car.photo.url
u'http://media.example.com/cars/chevy.jpg'

可以手动修改文件的名称:

>>> import os
>>> from django.conf import settings
>>> initial_path = car.photo.path
>>> car.photo.name = 'cars/chevy_ii.jpg'
>>> new_path = settings.MEDIA_ROOT + car.photo.name
>>> # Move the file on the filesystem
>>> os.rename(initial_path, new_path)
>>> car.save()
>>> car.photo.path
'/media/cars/chevy_ii.jpg'
>>> car.photo.path == new_path
True

Model的FileField是一个File对象,除了具有File对象的各种方法外,还有一个额外的save()方法:

FieldFile.save(name, content, save=True)

 name为存储名字,content为File或者File子类的实例

>>> car.photo.save('myphoto.jpg', content, save=False)
>>> car.save()

类似于

>>> car.photo.save('myphoto.jpg', content, save=True)

手动存储:

from django.core.files.base import ContentFile
photo=request.FILES.get('photo','')
if photo:   
    file_content = ContentFile(photo.read())   #创建File对象
    car.photo.save(photo.name, file_content)   #保存文件到car的photo域
    car.save()

  

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