How to Manage Google API Errors in Python

Question

I'm currently doing a lot of stuff with BigQuery, and am using a lot of try... except.... It looks like just about every error I get back from BigQuery is a apiclient.errors.HttpError, but with different strings attached to them, i.e.:

<HttpError 409 when requesting https://www.googleapis.com/bigquery/v2/projects/some_id/datasets/some_dataset/tables?alt=json returned "Already Exists: Table some_id:some_dataset.some_table">

<HttpError 404 when requesting https://www.googleapis.com/bigquery/v2/projects/some_id/jobs/sdfgsdfg?alt=json returned "Not Found: Job some_id:sdfgsdfg">

among many others. Right now the only way I see to handle these is to run regexs on the error messages, but this is messy and definitely not ideal. Is there a better way?

Answer 1

BigQuery is a REST API, the errors it uses follow standard HTTP error conventions.

In python, an HttpError has a resp.status field that returns the HTTP status code. As you show above, 409 is 'conflict', 404 is 'not found'.

For example:

from googleapiclient.errors import HttpError try:    ... except HttpError as err:   # If the error is a rate limit or connection error,   # wait and try again.   if err.resp.status in [403, 500, 503]:     time.sleep(5)   else: raise 

The response is also a json object, an even better way is to parse the json and read the error reason field:

if err.resp.get('content-type', '').startswith('application/json'):     reason = json.loads(err.content).get('error').get('errors')[0].get('reason') 

This can be: notFound, duplicate, accessDenied, invalidQuery, backendError, resourcesExceeded, invalid, quotaExceeded, rateLimitExceeded, timeout, etc.

Answer 2

Google Cloud now provides exception handlers:

from google.api_core.exceptions import AlreadyExists, NotFound try:     ... except AlreadyExists:     ... except NotFound:     ... 

This should prove more exact in catching the details of the error.

Please reference this source code to find other exceptions to utilize: http://google-cloud-python.readthedocs.io/en/latest/_modules/google/api_core/exceptions.html