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The distance is converted to meters, which is only what ST_DWithin measures in for projected SRIDs or geography columns; on a geographic-SRID geometry column it is interpreted in degrees. Refs geopython#164
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Closing this. Not something I'm going to keep current. |
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The SQLAlchemy backend converts
DWITHINandBEYONDdistances the wrong way. Inpygeofilter/backends/sqlalchemy/filters.py, kilometers are divided by 1000 and miles by 1609, whereboth should multiply to reach meters. A 5 kilometer query therefore searches 0.005 meters, so it
matches nothing, and the failure is silent: an empty result set rather than an error.
This multiplies instead, and uses 1609.34 for miles rather than 1609, which is the statute mile to
three decimal places rather than truncated.
The docstring gains a note that the value is converted to meters, and that meters is what
ST_DWithinmeasures in only for projected SRIDs or
geographycolumns. On a geographic SRID with ageometrycolumn it measures in degrees, so the conversion is right for the cases this backend supports and
worth stating rather than leaving for someone to rediscover.
Tests cover both units against the compiled SQL.
Fixes #164