Add dataset filter methods

Author: Ivan Tyurin

lib/sequel/plugins/enum_values.rb

@@ -35,19 +35,21 @@ def self.configure(model, options = {})
 				model.instance_exec do
 					@enum_values_caching = options.fetch(:caching, @enum_values_caching)
 
-					predicate_methods = options.fetch(:predicate_methods, false)
+					initialize_predicate_methods options.fetch(:predicate_methods, false)
 
-					transform_predicate_methods_to_enum_fields(predicate_methods)
-						.each do |field|
-							all_enum_fields[field][:enum_values].each do |enum_value|
-								define_predicate_method field, enum_value
-							end
-						end
+					@predicate_methods.each do |field|
+						all_enum_fields[field][:enum_values]
+							.each { |enum_value| define_predicate_method field, enum_value }
+					end
+
+					create_enum_subsets if @dataset
 				end
 			end
 
 			## Module for class methods
 			module ClassMethods
+				Plugins.after_set_dataset(self, :create_enum_subsets)
+
 				## Get enum values for specific field
 				## @param field [Symbol] name of enum field
 				## @return [Array<String>] values of enum
@@ -68,15 +70,16 @@ def enum_values(field)
 
 				private
 
-				def transform_predicate_methods_to_enum_fields(predicate_methods)
-					case predicate_methods
-					when TrueClass
-						all_enum_fields.keys
-					when FalseClass
-						[]
-					else
-						Array(predicate_methods)
-					end
+				def initialize_predicate_methods(predicate_methods_option)
+					@predicate_methods =
+						case predicate_methods_option
+						when TrueClass
+							all_enum_fields.keys
+						when FalseClass
+							[]
+						else
+							Array(predicate_methods_option)
+						end
 				end
 
 				def define_predicate_method(field, enum_value)
@@ -101,6 +104,27 @@ def raise_field_nonexistent(field)
 						"'#{table_name}' table does not have '#{field}' column"
 					)
 				end
+
+				## Creates dataset methods for filtering
+				## @return [Dataset]
+				## @example Get dataset with filter for `status` field of `Item` model
+				##   Item.created =>
+				##     "SELECT * FROM \"items\" WHERE (\"status\" = 'created')"
+				def create_enum_subsets
+					return if @predicate_methods.empty?
+
+					fields =
+						all_enum_fields
+							.select { |field, _options| @predicate_methods.include?(field) }
+
+					return if fields.empty?
+
+					dataset_module do
+						fields.each do |field, options|
+							options[:enum_values].each { |value| where value, field => value }
+						end
+					end
+				end
 			end
 		end
 	end

spec/sequel/plugins/enum_values_spec.rb

@@ -229,6 +229,62 @@
 			end
 		end
 	end
+
+	describe 'Sequel::Model.enum_filter' do
+		subject(:enum_filter) { item_class.public_send(enum_value).sql }
+
+		let(:predicate_methods) { true }
+
+		let(:item_class) do
+			Class.new(Sequel::Model(:items)).tap do |klass|
+				klass.plugin :enum_values, predicate_methods: predicate_methods
+			end
+		end
+
+		def filter_sql(column, value)
+			"SELECT * FROM \"items\" WHERE (\"#{column}\" = '#{value}')"
+		end
+
+		context 'with existing :type field' do
+			let(:field) { :type }
+
+			context 'with existing field value' do
+				let(:enum_value) { type_enum_values.first }
+
+				it { is_expected.to eq filter_sql(field, enum_value) }
+			end
+
+			context 'with nonexistent field value' do
+				let(:enum_value) { 'nonexistent' }
+
+				it { expect { enum_filter }.to raise_error(NoMethodError) }
+			end
+		end
+
+		context 'with existing :status field' do
+			let(:field) { :status }
+
+			context 'with existing field value' do
+				let(:enum_value) { status_enum_values.first }
+
+				it { is_expected.to eq filter_sql(field, enum_value) }
+			end
+
+			context 'with nonexistent field value' do
+				let(:enum_value) { 'nonexistent' }
+
+				it { expect { enum_filter }.to raise_error(NoMethodError) }
+			end
+		end
+
+		context 'with not included to predicate methods enum field' do
+			let(:predicate_methods) { :status }
+			let(:field) { :type }
+			let(:enum_value) { type_enum_values.first }
+
+			it { expect { enum_filter }.to raise_error(NoMethodError) }
+		end
+	end
 end
 
 # connection.drop_table :items