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BQ: Empty array when no results #184

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Feb 16, 2016
Merged

BQ: Empty array when no results #184

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BQ: Empty array when no results
hraban Feb 15, 2016
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BQ: JSON on query output, even when paging
hraban Feb 16, 2016
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2 changes: 1 addition & 1 deletion bigquery/api/sync_query.py
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Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ def main(project_id, query, timeout, num_retries):
pageToken=page_token,
**query_job['jobReference']).execute(num_retries=2)

print(json.dumps(page['rows']))
print(json.dumps(page.get('rows', [])))
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I would prefer None over an empty list. How does json.dumps() respond when passed None?

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$ python3 -c 'import json ; print(json.dumps(None))'
null

I went with [] because the return value is an array containing all the result rows, which feels like it should be an empty array when there are no rows. But I am almost apathetic towards this :P as long as it doesn't KeyError, I'm fine.

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Heh, fair enough... How about we do even better and do this:

rows = page.get('rows')

if rows:
    print json.dumps(rows)
else:
    print 'No results found.'

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Not a fan. The appeal of this script is its composability through valid JSON output on stdout; you can pipe it to jq or other JSON tools. Incidentally this is also why I chose []; by always returning an array you can just loop over the result no matter what.

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Interesting, I don't think we considered that a primary use case here. How about:

    # [START paging]
    # Page through the result set and print all results.
    results = []
    page_token = None

    while True:
        page = bigquery.jobs().getQueryResults(
            pageToken=page_token,
            **query_job['jobReference']).execute(num_retries=2)

        results.extend(page.get('rows', []))

        page_token = page.get('pageToken')
        if not page_token:
            break

    print(json.dumps(results))
    # [END paging]

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Ah! so you're saying paging would break the original script's JSON output?

This is a nice solution, good idea.

The valid JSON output is very nice in combination with jq because the raw output can be a bit.. raw :)

+1 !

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Cool, if you'll update your PR I'll get it merged. Thank you for your contribution!

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Done.


page_token = page.get('pageToken')
if not page_token:
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