Character string containing GeoJSON, or NULL if GeoJSON
written to file.
Arguments
x
sf object. Supports sf or sfc
opts
named list of options. Usually created with opts_write_geojson().
Default: empty list() to use the default options.
...
any extra named options override those in opts
json_opts
Named list of vanilla JSON options as used by write_json_str().
This is usually created with opts_write_json(). Default value is
an empty list() which means to use all the default JSON writing
options which is usually the correct thing to do when writing GeoJSON.