BigQuery: raise TypeError if wrong job_config type is passed to client job methods (load_table_from_*, query, ...)

[tswast]

Is your feature request related to a problem? Please describe.

It's a somewhat common problem to pass in a QueryJobConfig when you meant to create a LoadJobConfig. (I've done it!) This results in a difficult-to-debug error from the backend:

google.api_core.exceptions.BadRequest: 400 POST https://bigquery.googleapis.com/upload/bigquery/v2/projects/swast-scratch/jobs?uploadType=resumable: Required parameter is missing

Describe the solution you'd like

Instead, let's catch when someone passes in the wrong type to a job_config parameter and raise a ValueError with a more helpful message like: Expected a LoadJobConfig for the job_config parameter, but got job_config=....

Describe alternatives you've considered

• Continue to let the server catch these errors. The error message is unfortunately very difficult to debug, though, because we are sending a job resource of ambiguous type to the API.
• Fail somewhere else, such as when we create the resource to send to the API. This is more error-prone and gives us less ability to catch the error at the line that actually caused it.

Additional context

In response to internal issue 121343256.

[tswast]

QLogic folks, this is a good issue for you all to tackle.

[plamut]

As discussed with @tswast on the chat, I can also tackle this, as I am doing some extra hours this weekend.

@HemangChothani Let me know if you have already started working on this in the meantime to not duplicate the work (I heard that it's fine to start working on this).

[HemangChothani]

I have completed the task, it's in internal review process, soon I will create PR for that

…

On Sat, 19 Oct, 2019, 5:18 PM Peter Lamut, ***@***.***> wrote: As discussed with @tswast <https://github.com/tswast> offline, I can also tackle this, as I am doing some extra hours this weekend. — You are receiving this because you were assigned. Reply to this email directly, view it on GitHub <#9480?email_source=notifications&email_token=AMAR4JRX2ARUFC2M7RDUF2DQPLXZVA5CNFSM4JBEMUUKYY3PNVWWK3TUL52HS4DFVREXG43VMVBW63LNMVXHJKTDN5WW2ZLOORPWSZGOEBXNPIY#issuecomment-544135075>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AMAR4JV67IUIYEUXY6VUDTTQPLXZVANCNFSM4JBEMUUA> .

[plamut]

Oh, good to know, thanks.