Object mapper field selection issue using only().

[Charles-Antoine Dupont]

Hi,

I'm not sure if it is meant to be used, but the only way I have found to select certain fields of a model in query is to use .only(field_list)

e.g. model.objects.filter().only(field_list).all()

It seems to work, except I encountered a strange issue when filtering on a table with a partition key and two clustering key:

My specific case was similar to this one:

e.g. model.objects.filter(id__in=ids, other_text_field=some_string, start_date__gte=first_date, start_date__lt=end_date).only(field_list).all()

where  "id" is partition key, and other_text_field and start_date and clustering keys in that specific order.

For some reason, in that case, all fields will be returned, not just those in field_list.

However, if I create a table with no "other_text_field" and do not filter with it, the query is made with the fields in field_list.

I'm curious about the intent behind only() and if there is a way to make the driver more verbose as to what could've caused this behavior.

Thank you. 

[Alan Boudreault]

Hello Charles-Antoine,

Thanks for reporting this. I investigated your use case and there is effectively a bug in the object mapper. The bug is related to the use of only() when defered fields are present. I´ve created a ticket and we will work on this as soon as possible. See the following link for more information:

https://datastax-oss.atlassian.net/browse/PYTHON-560

Regards,

Alan

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Alan Boudreault

Software Engineer (Drivers) | alan.bo...@datastax.com