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Django处理文件上传File Uploads


       

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


<form enctype=            "multipart/form-data"             method=            "post"             action=            "/foo/"            >            


             <input type=            "file"             name=            "image"             />



request.FILES中的键来自于表单中的<input type="file" name="" />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           


            <ImageFieldFile: chevy.jpg>           


            >>> 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'




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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