Class: RGeo::GeoJSON::Coder

Inherits:
Object
  • Object
show all
Defined in:
lib/rgeo/geo_json/coder.rb

Overview

This object encapsulates encoding and decoding settings (principally the RGeo::Feature::Factory and the RGeo::GeoJSON::EntityFactory to be used) so that you can encode and decode without specifying those settings every time.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Coder

Create a new coder settings object. The geo factory is passed as a required argument.

Options include:

:geo_factory

Specifies the geo factory to use to create geometry objects. Defaults to the preferred cartesian factory.

:entity_factory

Specifies an entity factory, which lets you override the types of GeoJSON entities that are created. It defaults to the default RGeo::GeoJSON::EntityFactory, which generates objects of type RGeo::GeoJSON::Feature or RGeo::GeoJSON::FeatureCollection. See RGeo::GeoJSON::EntityFactory for more information.



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# File 'lib/rgeo/geo_json/coder.rb', line 24

def initialize(opts = {})
  @geo_factory = opts[:geo_factory] || RGeo::Cartesian.preferred_factory
  @entity_factory = opts[:entity_factory] || EntityFactory.instance
  @num_coordinates = 2
  @num_coordinates += 1 if @geo_factory.property(:has_z_coordinate)
  @num_coordinates += 1 if @geo_factory.property(:has_m_coordinate)
end

Instance Attribute Details

#entity_factory ⇒ Object (readonly)

Returns the RGeo::GeoJSON::EntityFactory used to generate GeoJSON wrapper entities.



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# File 'lib/rgeo/geo_json/coder.rb', line 95

def entity_factory
  @entity_factory
end

#geo_factory ⇒ Object (readonly)

Returns the RGeo::Feature::Factory used to generate geometry objects.



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# File 'lib/rgeo/geo_json/coder.rb', line 90

def geo_factory
  @geo_factory
end

Instance Method Details

#decode(input) ⇒ Object

Decode an object from GeoJSON. The input may be a JSON hash, a String, or an IO object from which to read the JSON string. If an error occurs, nil is returned.



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# File 'lib/rgeo/geo_json/coder.rb', line 61

def decode(input)
  if input.is_a?(IO)
    input = input.read rescue nil
  end
  if input.is_a?(String)
    input = MultiJson.load(input)
  end
  return unless input.is_a?(Hash)

  case input["type"]
  when "FeatureCollection"
    features = input["features"]
    features = [] unless features.is_a?(Array)
    decoded_features = []
    features.each do |f|
      if f["type"] == "Feature"
        decoded_features << decode_feature(f)
      end
    end
    @entity_factory.feature_collection(decoded_features)
  when "Feature"
    decode_feature(input)
  else
    decode_geometry(input)
  end
end

#encode(object) ⇒ Object

Encode the given object as GeoJSON. The object may be one of the geometry objects specified in RGeo::Feature, or an appropriate GeoJSON wrapper entity supported by this coder’s entity factory.

This method returns a JSON object (i.e. a hash). In order to generate a string suitable for transmitting to a service, you will need to JSON-encode it. This is usually accomplished by calling to_json on the hash object, if you have the appropriate JSON library installed.

Returns nil if nil is passed in as the object.



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# File 'lib/rgeo/geo_json/coder.rb', line 43

def encode(object)
  if @entity_factory.is_feature_collection?(object)
    {
      "type" => "FeatureCollection",
      "features" => @entity_factory.map_feature_collection(object) { |f| encode_feature(f) },
    }
  elsif @entity_factory.is_feature?(object)
    encode_feature(object)
  elsif object.nil?
    nil
  else
    encode_geometry(object)
  end
end