在Django视图中获取Google App Engine blob信息

问题描述

这是

我有一部分图片上传到GAE Blobstore工作。这是我做的：

在

$ $ p $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ b Property，
related_name =photo_features
）
caption = models.CharField（
max_length = 100
）
blob_key = models.CharField（
max_length = 100
）

在 admin中。 py 我创建了一个包含change_form呈现的覆盖的管理条目，以允许将正确的操作插入到Blobstore上传网址：

 
 
 $ def $ render_form （self，request，context，* args，** kwargs）：
 from google.appengine.ext如果kwargs.has_key（add）为导入blobstore 
：
 co ntext ['blobstore_url'] = blobstore.create_upload_url（'/ admin / add-photo-feature'）
 else：
 context ['blobstore_url'] = blobstore.create_upload_url（'/ admin / update-photo 
 return super（PhotoFeatureAdmin，self）.render_change_form（request，context，args，kwargs）
  

当我使用标准Django时，我希望在GAE更新BlobStore而不是 BlobstoreUploadHandler 时使用Django视图来处理结果。我创建了以下视图（根据render_change_form方法）并更新了 urls.py ：

  def add_photo_feature（request）：
 
 def update_photo_feature（request）：
  

这一切都很好，但一旦我进入视图方法，我有点失落。如何从请求对象中获取Blob密钥，以便我可以使用PhotoFeature存储它？我使用标准的Django，而不是Django非rel。我发现相关的问题，但似乎并不包含解决方案。我还检查了传入视图的请求对象，但找不到与blob关键字有关的任何内容。

编辑：

Django请求对象包含一个FILES字典，它会给我一个 InMemoryUploadedFile 。我认为，我应该能够从中检索到BLOB键...

编辑2：

要清楚：上传的照片出现在Blobstore中;那部分工作。

$ b 编辑3：

根据Daniel的建议，我从项目，其中包含建议的上传处理程序，并将其添加到我的SETTINGS.PY。尝试上传时导致以下异常：

 'BlobstoreFileUploadHandler'对象没有属性'content_type_extra'
  

解决方案

解决这个问题非常棘手。我找到的最好的解决方案是使用项目中的文件上传处理程序（它是关联的与Django-Nonrel，但不依赖于它）。这应该处理所需的逻辑，把blob键放到 request.FILES 中，就像在Django中所期望的那样。

我忘了django-nonrel使用补丁版本的Django，其中一个补丁是在这里添加内容类型额外字段。您可以通过继承上传处理程序来复制功能，如下所示：

  from djangoappengine import storage 
 class BlobstoreFileUploadHandler（storage。 BlobstoreFileUploadHandler）：
把blob关键信息添加到文件对象的Handler。
 $ b $ def new_file（self，field_name，* args，** kwargs）：
＃我们需要重新处理POST数据以获取blobkey信息。 
 meta = self.request.META 
 meta ['wsgi.input']。seek（0）
 fields = cgi.FieldStorage（meta ['wsgi.input']，environ = meta ）
 if field_name in fields：
 current_field = fields [field_name] 
 self.content_type_extra = current_field.type_options 
 super（BlobstoreFileUploadHandler，self）.new_file（field_name，
 * args，** kwargs）
  

并且在settings.py中引用这个子类而不是原来的。

This is a follow up question for Django on Google App Engine: cannot upload images

I got part of the upload of images to GAE Blobstore working. Here's what I did:

In models.py I created a model PhotoFeature:

class PhotoFeature(models.Model):
    property = models.ForeignKey(
        Property,
        related_name = "photo_features"
    )
    caption = models.CharField(
        max_length = 100
    )
    blob_key = models.CharField(
        max_length = 100
    )

In admin.py I created an admin entry with an override for the rendering of the change_form to allow for insert of the correct action to the Blobstore upload url:

class PhotoFeatureAdmin(admin.ModelAdmin):
    list_display = ("property", "caption")
    form = PhotoFeatureForm

    def render_change_form(self, request, context, *args, **kwargs):
        from google.appengine.ext import blobstore
        if kwargs.has_key("add"):
            context['blobstore_url'] = blobstore.create_upload_url('/admin/add-photo-feature')
        else:
            context['blobstore_url'] = blobstore.create_upload_url('/admin/update-photo-feature')
        return super(PhotoFeatureAdmin, self).render_change_form(request, context, args, kwargs)

As I use standard Django, I want to use the Django views to process the result once GAE has updated the BlobStore in stead of BlobstoreUploadHandler. I created the following views (as per the render_change_form method) and updated urls.py:

def add_photo_feature(request):

def update_photo_feature(request):

This all works nicely but once I get into the view method I'm a bit lost. How do I get the Blob key from the request object so I can store it with PhotoFeature? I use standard Django, not Django non-rel. I found this related question but it appears not to contain a solution. I also inspected the request object which gets passed into the view but could not find anything relating to the blob key.

EDIT:

The Django request object contains a FILES dictionary which will give me an instance of InMemoryUploadedFile. I presume that somehow I should be able to retrieve the blob key from that...

EDIT 2:

Just to be clear: the uploaded photo appears in the Blobstore; that part works. It's just getting the key back from the Blobstore that's missing here.

EDIT 3:

As per Daniel's suggestion I added storage.py from the djangoappengine project which contains the suggested upload handler and added it to my SETTINGS.PY. This results in the following exception when trying to upload:

'BlobstoreFileUploadHandler' object has no attribute 'content_type_extra'

解决方案

This is really tricky to fix. The best solution I have found is to use the file upload handler from the djangoappengine project (which is associated with django-nonrel, but does not depend on it). That should handle the required logic to put the blob key into request.FILES, as you'd expect in Django.

Edit

I'd forgotten that django-nonrel uses a patched version of Django, and one of the patches is here to add the content-type-extra field. You can replicate the functionality by subclassing the upload handler as follows:

from djangoappengine import storage
class BlobstoreFileUploadHandler(storage.BlobstoreFileUploadHandler):
    """Handler that adds blob key info to the file object."""

    def new_file(self, field_name, *args, **kwargs):
      # We need to re-process the POST data to get the blobkey info.
      meta = self.request.META
      meta['wsgi.input'].seek(0)
      fields = cgi.FieldStorage(meta['wsgi.input'], environ=meta)
      if field_name in fields:
          current_field = fields[field_name]
          self.content_type_extra = current_field.type_options
      super(BlobstoreFileUploadHandler, self).new_file(field_name,
                                                       *args, **kwargs)

and reference this subclass in your settings.py rather than the original.

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