Computed fields

lib/rasti/db/collection.rb

@@ -14,7 +14,7 @@ def collection_name
         end
 
         def collection_attributes
-          @collection_attributes ||= model.attributes - relations.keys
+          @collection_attributes ||= model.attributes - relations.keys - computed_attributes.keys
         end
 
         def primary_key
@@ -47,6 +47,10 @@ def queries
           @queries ||= Hash::Indifferent.new
         end
 
+        def computed_attributes
+          @computed_attributes ||= Hash::Indifferent.new
+        end
+
         private
 
         def set_collection_name(collection_name)
@@ -91,6 +95,11 @@ def query(name, lambda=nil, &block)
           end
         end
 
+        def computed_attribute(name, &block)
+          raise "Computed Attribute #{name} already exists" if computed_attributes.key? name
+          computed_attributes[name] = block.call
+        end
+
       end
 
       def initialize(environment)

lib/rasti/db/computed_attribute.rb

@@ -0,0 +1,22 @@
+module Rasti
+  module DB
+    class ComputedAttribute
+
+      attr_reader :identifier
+
+      def initialize(identifier, &join)
+        @identifier = identifier
+        @join = join
+      end
+
+      def apply_join(dataset)
+        join ? join.call(dataset) : dataset
+      end
+
+      private
+
+      attr_reader :join
+
+    end
+  end
+end

lib/rasti/db/nql/nodes/attribute.rb

@@ -0,0 +1,37 @@
+module Rasti
+  module DB
+    module NQL
+      module Nodes
+        class Attribute < Treetop::Runtime::SyntaxNode
+
+          def identifier(collection_class)
+            if computed? collection_class
+              collection_class.computed_attributes[column].identifier
+            else
+              tables.empty? ? Sequel[column] : Sequel[tables.join('__').to_sym][column]
+            end
+          end
+
+          def tables
+            _tables.elements.map{ |e| e.table.text_value }
+          end
+
+          def column
+            _column.text_value.to_sym
+          end
+
+          def computed_attributes(collection_class)
+            computed?(collection_class) ? [column] : []
+          end
+
+          private
+
+          def computed?(collection_class)
+            collection_class.computed_attributes.key? column
+          end
+
+        end
+      end
+    end
+  end
+end

lib/rasti/db/nql/nodes/binary_node.rb

@@ -8,6 +8,10 @@ def dependency_tables
             values.flat_map(&:dependency_tables)
           end
 
+          def computed_attributes(collection_class)
+            left.computed_attributes(collection_class) | right.computed_attributes(collection_class)
+          end
+
           def values
             @values ||= values_for(left) + values_for(right)
           end

lib/rasti/db/nql/nodes/comparisons/base.rb

@@ -6,7 +6,11 @@ module Comparisons
           class Base < Treetop::Runtime::SyntaxNode
 
             def dependency_tables
-              field.tables.empty? ? [] : [field.tables.join('.')]
+              attribute.tables.empty? ? [] : [attribute.tables.join('.')]
+            end
+
+            def computed_attributes(collection_class)
+              attribute.computed_attributes(collection_class)
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/equal.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class Equal < Base
 
-            def filter_condition
-              { field.identifier => argument.value }
+            def filter_condition(collection_class)
+              { attribute.identifier(collection_class) => argument.value }
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/greater_than.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class GreaterThan < Base
 
-            def filter_condition
-              field.identifier > argument.value
+            def filter_condition(collection_class)
+              attribute.identifier(collection_class) > argument.value
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/greater_than_or_equal.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class GreaterThanOrEqual < Base
 
-            def filter_condition
-              field.identifier >= argument.value
+            def filter_condition(collection_class)
+              attribute.identifier(collection_class) >= argument.value
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/include.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class Include < Base
 
-            def filter_condition
-              Sequel.ilike(field.identifier, "%#{argument.value}%")
+            def filter_condition(collection_class)
+              Sequel.ilike(attribute.identifier(collection_class), "%#{argument.value}%")
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/less_than.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class LessThan < Base
 
-            def filter_condition
-              field.identifier < argument.value
+            def filter_condition(collection_class)
+              attribute.identifier(collection_class) < argument.value
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/less_than_or_equal.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class LessThanOrEqual < Base
 
-            def filter_condition
-              field.identifier <= argument.value
+            def filter_condition(collection_class)
+              attribute.identifier(collection_class) <= argument.value
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/like.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class Like < Base
 
-            def filter_condition
-              Sequel.ilike(field.identifier, argument.value)
+            def filter_condition(collection_class)
+              Sequel.ilike(attribute.identifier(collection_class), argument.value)
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/not_equal.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class NotEqual < Base
 
-            def filter_condition
-              Sequel.negate(field.identifier => argument.value)
+            def filter_condition(collection_class)
+              Sequel.negate(attribute.identifier(collection_class) => argument.value)
             end
 
           end

lib/rasti/db/nql/nodes/comparisons/not_include.rb

@@ -5,8 +5,8 @@ module Nodes
         module Comparisons
           class NotInclude < Base
 
-            def filter_condition
-              ~ Sequel.ilike(field.identifier, "%#{argument.value}%")
+            def filter_condition(collection_class)
+              ~ Sequel.ilike(attribute.identifier(collection_class), "%#{argument.value}%")
             end
 
           end

lib/rasti/db/nql/nodes/conjunction.rb

@@ -4,8 +4,8 @@ module NQL
       module Nodes
         class Conjunction < BinaryNode
 
-          def filter_condition
-            Sequel.&(*values.map(&:filter_condition))
+          def filter_condition(collection_class)
+            Sequel.&(*values.map { |value| value.filter_condition(collection_class) } )
           end
 
         end

lib/rasti/db/nql/nodes/disjunction.rb

@@ -4,8 +4,8 @@ module NQL
       module Nodes
         class Disjunction < BinaryNode
 
-          def filter_condition
-            Sequel.|(*values.map(&:filter_condition))
+          def filter_condition(collection_class)
+            Sequel.|(*values.map { |value| value.filter_condition(collection_class) } )
           end
 
         end

lib/rasti/db/nql/nodes/parenthesis_sentence.rb

@@ -8,8 +8,12 @@ def dependency_tables
             sentence.dependency_tables
           end
 
-          def filter_condition
-            sentence.filter_condition
+          def computed_attributes(collection_class)
+            sentence.computed_attributes(collection_class)
+          end
+
+          def filter_condition(collection_class)
+            sentence.filter_condition collection_class
           end
 
         end

lib/rasti/db/nql/nodes/sentence.rb

@@ -8,8 +8,12 @@ def dependency_tables
             proposition.dependency_tables
           end
 
-          def filter_condition
-            proposition.filter_condition
+          def computed_attributes(collection_class)
+            proposition.computed_attributes collection_class
+          end
+
+          def filter_condition(collection_class)
+            proposition.filter_condition collection_class
           end
 
         end