Background: I'm taking data in my Python/AppEngine project and creating a .tsv file so that I can create charts with d3.js. Right now I'm writing the CSV with each page load; I want to instead store the file once in Google Cloud Storage and read it from there.
How I'm currently writing the file, each time the page is loaded!:
def get(self): ## this gets called when loading myfile.tsv from d3.js
datalist = MyEntity.all()
self.response.headers['Content-Type'] = 'text/csv'
writer = csv.writer(self.response.out, delimiter='')
writer.writerow(['field1', 'field2'])
for eachco in datalist:
writer.writerow([eachco.variable1, eachco.variable2])
And while inefficient, this is working just fine.
Using this Google Cloud Storage documentation, I've been trying to get something like this working:
def get(self):
filename = '/bucket/myfile.tsv'
datalist = MyEntity.all()
bucket_name = os.environ.get('BUCKET_NAME', app_identity.get_default_gcs_bucket_name())
write_retry_params = gcs.RetryParams(backoff_factor=1.1)
writer = csv.writer(self.response.out, delimiter='')
gcs_file = gcs.open(filename, 'w', content_type='text/csv', retry_params=write_retry_params)
gcs_file.write(writer.writerow(['field1', 'field2']))
for eachco in datalist:
gcs_file.write(writer.writerow([eachco.variable1, eachco.variable2]))
gcs_file.close()
But I'm getting:
TypeError: Expected str but got <type 'NoneType'>.
I thought that the output of csv.writer would be a string, so I'm not sure why I'm getting the TypeError.
So I can think of two situations:
- I've got something screwed up in my code that writes the tsv to
Cloud Storage. It should be simple to iterate through and write a TSV/CSV file to Cloud Storage though, right?
- I've gone about this the completely wrong way
entirely, and should maybe even use BlobStore or db.TextProperty()
to store this .tsv data. (The files aren't that big; definitely
well under 1MB)
I'd appreciate any help!
edit - full traceback
Traceback (most recent call last):
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.1/webapp2.py", line 1530, in __call__
rv = self.router.dispatch(request, response)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.1/webapp2.py", line 1278, in default_dispatcher
return route.handler_adapter(request, response)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.1/webapp2.py", line 1102, in __call__
return handler.dispatch()
File "/mydirectory/myapp/handlers.py", line 21, in dispatch
webapp2.RequestHandler.dispatch(self)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.1/webapp2.py", line 572, in dispatch
return self.handle_exception(e, self.app.debug)
File "/Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib/webapp2-2.5.1/webapp2.py", line 570, in dispatch
return method(*args, **kwargs)
File "/mydirectory/myapp/thisapp.py", line 384, in get
gcs_file.write(writer.writerow(['field1', 'field2']))
File "lib/cloudstorage/storage_api.py", line 754, in write
raise TypeError('Expected str but got %s.' % type(data))
TypeError: Expected str but got <type 'NoneType'>.
See Question&Answers more detail:
os