Hi Ian,
Interesting. Is the Joining datastore somewhere online already?
I'll admit to having written similar datastores previously. One of my
ideas for using this kind of DataStore would be to leverage functions
like those in the GS Query Layer extension to pull attributes from other
layers. Similarly, it ought to be trivial to pull a column from a CSV
on disk.
As one starts down that path, there are syntactical annoyances (I cannot
see an easy way to say "get a bunch of columns from other there" without
having a function call per column), and performance considerations
(reading from a file/database repeated for the same information among
separate queries is less than ideal, so caching would be nice). That
said, in a pinch, this approach may provide a really, really quick
solution.
Cheers,
Jim
On 11/3/20 1:53 PM, Ian Turton wrote:
This looks interesting, I wonder how hard it would be to merge in the
work I did on Joining datastores that could create "views" across
non-jdbc datastores so you could add a CSV to a geometry in another
store, I should dig that code out and look at it again. Maybe a
christmas lockdown project?
Ian
On Tue, 3 Nov 2020 at 18:19, Jim Hughes <jhug...@ccri.com
<mailto:jhug...@ccri.com>> wrote:
Hi all,
At various times, Jody and I have chatted about having a "CQL
View" in
GeoServer (or something similar akin to the SQL Views) that'd
leverage
the Transform module and allow one to add columns to a FeatureSource
based on expressions. Such expressions could use existing or
custom CQL
functions and that'd open a world of possibilities.
Last week, I asked Jody about this idea again and he indicated
that one
would really just need to write a DataStoreFactory. I banged out an
initial implementation as a starting place for the conversation.
This
implementation provides a way to project down to a subset of
attributes
as well as add new columns/attributes to a FeatureStore.
If folks like it as-is, I'd be happy to add unit tests, and
documentation wherever we see fit. Thanks in advance for some
feedback
on this idea!
https://github.com/geotools/geotools/pull/3196/files
Cheers,
Jim
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