CQL Nested structure selection with collections

[Charles-Antoine Dupont]

Hi,

From what I can see, nested structures like UDTs can be selected in CQL using the dot notation (e.g. "SELECT field.subfield").

Is there a way to select fields of a UDT within a collection(set/list/map) or do we need to select the entire collection and manually process the result?

e.g. 

if we have the field "addresses" which is a list of UDT "address",

which contains many fields, but 

we only want to get the subfield "city", in order to get a list of cities as a result.

ps. This use case could be solved differently, it's just to illustrate the structure type and how I wish to select it.

Thank you

[Adam Holmberg]

Presently the mapper will only select the entire UDT value. There is no way to select a single subfield.

There is a pattern in the model query set that allows one to specify *only* certain columns, but that pattern was not extended into UDTs. If this is an important use case for you, I would welcome a ticket on the matter.

https://datastax-oss.atlassian.net/projects/PYTHON/summary

Since you mention other solutions already, I won't elaborate on the alternatives.

Regards,

Adam Holmberg

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