[GeoNode-devel] Table Join - Field Format Conversion

[Paolo Corti]

Hi Jeff
As you know, I will need start using this stuff in GeoNode.
Can you confirm me that this is the latest version of the code?
https://github.com/jj0hns0n/geonode/tree/table-join

thanks
p

On Mon, Feb 23, 2015 at 4:33 PM, Jeffrey Johnson <ortelius at gmail.com> wrote:
> Hi Gents,
>
> As mentioned in a previous post and in GNIP #1915, I've been working
> on adding a new 'datatables' contrib module for GeoNode that allows
> for uploading of CSV or other delimited files and loading these into
> PostgreSQL and joining a existing geometry to them. You can see the
> implementation here
> https://github.com/jj0hns0n/geonode/compare/table-join?expand=1 ...
> Everything is mostly working and functional at an API level. You can
> see the test setup we are using in tabular-api/code/tabular_test.py
> (this will get converted into a more complete integration test suite).
>
> The largest issue we have run into in our testing is field type
> mismatches. The simplest case is an int field in either the table or
> the layer and a string field in the other. There are also issues with
> the field being specified with leading zeroes or other characters in
> one of the 2 join components and not in the other. The folks at
> harvard have found other instances where they need to actually join
> the contents of 2 fields together before joining.
>
> Some tickets in my own fork for background/reference.
>
> https://github.com/jj0hns0n/geonode/issues/34
> https://github.com/jj0hns0n/geonode/issues/30
> https://github.com/jj0hns0n/geonode/issues/40
> https://github.com/jj0hns0n/geonode/issues/50
> https://github.com/jj0hns0n/geonode/issues/49 (the ticket Im dealing
> with _right now_)
>
> Raman (@raprasad) and I have discussed several options for dealing
> with this kind of problem and we decided to add a class
> JoinTargetFormatType that could store information necessary to do
> these kinds of conversions. You can see that class here
> https://github.com/jj0hns0n/geonode/blob/table-join/geonode/contrib/datatables/models.py#L51
> which is used in the JoinTarget class here
> https://github.com/jj0hns0n/geonode/blob/table-join/geonode/contrib/datatables/models.py#L71
> ... The basic idea is that you could have a set of pre-defined
> transformation functions or include some regex or a python function to
> do the conversion. None of this is hooked up yet, but thats the basic
> idea.
>
> So, we wanted to consult with all of you to see if anyone had any
> ideas about how best to hook this kind of thing up ... or perhaps some
> words of caution about how NOT to do this.
>
> Happy to discuss further if anyone has any questions or is unclear on
> what we are trying to do.
>
> Thanks in advance,
>
> Jeff
>
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-- 
Paolo Corti
Geospatial software developer
web: http://www.paolocorti.net
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