Parameter returnDistinctValues doesn't work

koopjs / FeatureServer

An open source Geoservices Implementation (deprecated)

https://geoservices.github.io

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Parameter returnDistinctValues doesn't work #244

Open mcasamayorpolo opened 1 year ago

mcasamayorpolo commented 1 year ago

There is an issue with the parameter returnDistinctValues:true. If I make a query with the following parameters:

where: 1=1
returnGeometry: false
spatialRel: esriSpatialRelIntersects
outFields: city
returnDistinctValues: true
orderByFields: city
outSR: 102100
resultOffset: 0
resultRecordCount: 1000

The result of the query is the following:

As you can see the parameter returnDistinctValues doesn't work. How can I fix this issue?

Thank you in advance for your help. :)

rgwozdz commented 1 year ago

As far as I know, FeatureServer doesn't currently support this parameter. You'd have to design a solution to pass the parameter on to the Winnow dependency, then PR Winnow change to convert the parameter to the appropriate SQL query against the geojson. Winnow uses AlaSQL, which does appear to support DISTINCT: https://github.com/AlaSQL/alasql/wiki/Distinct.