Widen the scope of GeoJSON.write

[rafaqz]

It seems that write does not work with all AbstractGeometry. I'm not sure if that is intentional. But currently e.g. ArchGDAL.IGeometry does not work.

julia> using GADM, GeoJSON

julia> GeoJSON.write(GADM.get("MUS").geom[1])
ERROR: MethodError: no method matching write(::ArchGDAL.IGeometry{ArchGDAL.wkbMultiPolygon})
Closest candidates are:
  write(::AbstractFeatureCollection) at ~/.julia/packages/GeoJSON/JVqvX/src/GeoJSON.jl:40
  write(::AbstractGeometryCollection) at ~/.julia/packages/GeoJSON/JVqvX/src/GeoJSON.jl:40
  write(::AbstractFeature) at ~/.julia/packages/GeoJSON/JVqvX/src/GeoJSON.jl:40
  ...
Stacktrace:
 [1] top-level scope
   @ REPL[33]:1

In the docs we say that any AbstractGeometry will work:

help?> GeoJSON.write
  write(obj)

  Create a GeoJSON string from an object that implements the GeoInterface, either AbstractGeometry,
  AbstractFeature or AbstractFeatureCollection.

The current workaround is to wrap in a Feature.

[rafaqz]

Is there a reason we have a limited list of types dispatched on here, instead of just using AbstractGeometry ?
https://github.com/JuliaGeo/GeoJSON.jl/blob/master/src/GeoJSON.jl#L53-L57

[visr]

I think that can indeed just be AbstractGeometry. As far as I can see all of the current GeoInterface subtypes of AbstractGeometry are supported by the GeoJSON format. ArchGDAL.IGeometry should work through geo2dict.

[rafaqz]

Ok, I'll change that

[visr]

The example above, GeoJSON.write(GADM.get("MUS").geom[1]), now works, since #42. We still need to test this however. Currently only objects from this package are tested. We could test with GADM/ArchGDAL, or perhaps just something small like https://github.com/evetion/WellKnownGeometry.jl.

[rafaqz]

Yes it would be nice to test this. Leaflet.jl already tests it with GADM.jl/ArchGDAL.jl, so maybe WellKnownGeometry.jl.

[rafaqz]

This works now