Support Attributes

[keithdoggett]

This adds support for the standard Postgresql attributes and RGeo features as attributes.

Changes:

• Set the adapter name as postgresql in the type module that is used for determining which types ActiveRecord should use. This fixes Unknown type Jsonb when using Attributes API.  #267 and Unable to create an attribute for an array #284. Now users won't have to redefine Postgres attributes if they want them available in their app, but the downside is that if custom types were registered under postgis they will have to be changed to postgresql.
• Change the OID::Spatial module to accept keywords as arguments (geo_type, srid, has_z, has_m, geographic) instead of oid and sql_type. This is a necessary step to allow RGeo features as attributes because attributes access the type directly and do not pass a sql_type in.
• Modify initialize_type_map to parse sql_type then define the OID for each column.
• Register all RGeo column types as attributes using OID::Spatial.

With these changes, we can define attributes like this:

class SpatialClass < ActiveRecord::Base
  attribute :geo_point, :st_point, srid: 4326, geographic: true
end

and it doesn't need an associated column in the database.

Importantly, this allows for the proper joining of spatial data (#210), although it is not seamless yet. In order to properly format RGeo features from a join, the spatial column needs to be re-defined as an attribute on the target table. For example:

class SpatialFoo < ActiveRecord::Base
 belongs_to :foo

 # has column geo_point (:st_point, srid: 4326, geographic: true)
end

class Foo < ActiveRecord::Base
 has_one :spatial_foo
 
 # re-define geo_point here so join works
 attribute :geo_point, :st_point, srid: 4326, geographic: true
end

# perform a query where geo_point is joined to foo
foo = Foo.joins(:spatial_foo).select("foos.id, spatial_foos.geo_point").first
p foo.geo_point.class
# => RGeo::Geographic::SphericalPointImpl
p foo.geo_point.srid
# => 4326

TODO:

• Add support for attributes
• Update README with examples
• Update History

[BuonOmo]

Still some todos left on README, and history to update. I've also made some comments, mostly questions to make sure I understood the code correctly.

[BuonOmo]

The documentation should be updated as well

[keithdoggett]

Yes, good point I'll do that!

[BuonOmo]

Did you plan anything for that ? 🙂

[keithdoggett]

I'll open up an issue once this is approved 😅

[BuonOmo]

That looks great, I added one last review, tell me what you think about it. Otherwise we'll be ready to merge soon 😄

[BuonOmo]

LGTM! Great work, thank you 💪