+++ It is working – See solution at bottom +++ I am a relative

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Asked: June 11, 20262026-06-11T14:45:50+00:00 2026-06-11T14:45:50+00:00

+++ It is working – See solution at bottom +++ I am a relative

0

+++ It is working – See solution at bottom +++

I am a relative newbie to Google App Engine and Python.

I have some large text content (content in a variable and not an external file) that I am manipulating in my program. GAE does not let me write to files so I would like to store them in blobstore. Can I do this in GAE and Python? and if so, how?

An example code snippet would be greatly appreciated.

Thanks.

+++ Updated Question +++

I tried following the example at the link you provided modified by the example at: http://blog.notdot.net/2010/03/Implementing-a-dropbox-service-with-the-Blobstore-API-Part-1 to enable the saving of the blobstore key in the datastore. When the time comes to retrieve the file (which is an html file), I want to retrieve the BlobKey using the TemplateName.

I ended up with something like this:

In models.py I have:

class GeneratedFiles(ndb.Model):
  TemplateName = ndb.StringProperty()
  BlobKey = blobstore.BlobReferenceProperty()
  Status = ndb.StringProperty(default="Pending Translation")

In a class, in a .py file I have:

class TokenFileGen(BaseHandler):
    def get(self):
        template = jinja_environment.get_template(FileName)     
        blobtext = template.render(tokenvals = tokendict)
        bloboutput = (blobtext.encode('utf-8'))
        # Create the file
        file_name = files.blobstore.create(mime_type='application/octet-stream')
        # Open the file and write to it
        with files.open(file_name, 'a') as fl:
            fl.write(bloboutput)
        # Finalize the file. Do this before attempting to read it.
        files.finalize(file_name)
        # Get the file's blob key
        blob_key = files.blobstore.get_blob_key(file_name)
        logging.info('QQQ: blob_key: %s' % blob_key)
        f = GeneratedFiles(
            TemplateName = templateName
            , BlobKey = blob_key                       
            , Status = 'Published'
            )
        f.put()
        ...

I get a TypeError(‘Cannot set non-property %s’ % name) TypeError: Cannot set non-property blob

My logging statement returned the following:
INFO 2012-09-21 05:20:24,177 token.py:551] QQQ: blob_key: vL117vQ4dlIPoUwXbREmbeqUnZU7nJ6ELMma8u1bFHGUfgEfOfS7HfAdFUvXc1EC

I thought I was following the example fairly closely. Any idea how I can get this to work?

Thanks for any assistance.

+++ update 2 +++

Ok, I am now able to save the Blobstore reference in the following model:

class GeneratedFiles(ndb.Model):
  TemplateName = ndb.StringProperty()
  BlobKey = ndb.BlobKeyProperty()

The code that saved this is:

file_name = files.blobstore.create(mime_type='application/octet-stream')
with files.open(file_name, 'a') as fl:
    fl.write(bloboutput)
files.finalize(file_name)
blob_key = files.blobstore.get_blob_key(file_name)
logging.info('QQQ: blob_key: %s' % blob_key)
f = GeneratedFiles(
    TemplateName = templateName
    , BlobKey = blob_key                       
    )
f.put()

I am now trying to retrieve and download the file:

class FileDownloadHandler(blobstore_handlers.BlobstoreDownloadHandler):
    def get(self, genfile_id):
        iden = int(genfile_id)
        file_info = ndb.Key('GeneratedFiles', iden).get()
        if not file_info or not file_info.BlobKey:
            self.error(404)
            return
        else:
            blob_key = file_info.BlobKey
        logging.info('QQQ: FileDownloadHandler/blob_key: %s' % blob_key)
        self.send_blob(blob_key, save_as=True)

I am getting a error: ValueError: Expected BlobInfo value for blob_key_or_info. on the last line.

Just prior to the error msg, I get my log info:

INFO     2012-09-21 19:19:44,219 genfile.py:131] QQQ: FileDownloadHandler/blob_key: sGxZRNu94u1kZ9ezpAeQFhyOLSZFYNX8RSAbXU78MLjjUKOohV0wyWnZZEQf6ScC

I found some references that mention URLencoding in conjunction with this error. Could this be the problem? If so, what would URLencoding look like in my case and where should I place it (when I store the blob_key or after I retrieve id from ndb.datastore?

Thanks for any assistance.

+++ the solution +++

The key was changing the self.send_blob statement as follows (referencing blobstore and BlobInfo).

self.send_blob(blobstore.BlobInfo(file_info.blob), save_as=True)

I also changed the name of the attribute BlobKey to blob (was getting an error and error went away after I did this although I do not understand why that would make a difference).