init

lib/smql_to_ar/query_builder.rb

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+# SmqlToAR - Builds AR-querys: Converts SMQL to ActiveRecord
+# Copyright (C) 2011 Denis Knauf
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+class SmqlToAR
+	#######################################################################################
+	# Baut die Queries zusammen.
+	class QueryBuilder
+		# Erzeugt einen eindeutigen Identikator "cX", wobei X iteriert wird.
+		class Vid
+			attr_reader :vid
+			def initialize( vid)  @vid = vid  end
+			def to_s() ":c#{@vid}" end
+			def to_sym() "c#{@vid}".to_sym end
+			alias sym to_sym
+			def to_i()  @vid  end
+		end
+
+		attr_reader :table_alias, :model, :table_model, :base_table, :_where, :_select, :_wobs, :_joins
+		attr_accessor :logger
+		@@logger = SmqlToAR.logger
+
+		def initialize model
+			@logger = @@logger
+			@table_alias = Hash.new do |h, k|
+				k = Array.wrap k
+				h[k] = "smql,#{k.join(',')}"
+			end
+			@_vid, @_where, @_wobs, @model, @quoter = 0, [], {}, model, model.connection
+			@base_table = [model.table_name.to_sym]
+			@table_alias[ @base_table] = @base_table.first
+			t = quote_table_name @table_alias[ @base_table]
+			@_select, @_joins, @_joined, @_includes, @_order = ["DISTINCT #{t}.*"], "", [], [], []
+			@table_model = {@base_table => @model}
+		end
+
+		def vid()  Vid.new( @_vid+=1)  end
+
+		# Jede via where uebergebene Condition wird geodert und alle zusammen werden geundet.
+		# "Konjunktive Normalform".  Allerdings duerfen Conditions auch Komplexe Abfragen enthalten.
+		# Ex: builder.where( 'a = a', 'b = c').where( 'c = d', 'e = e').where( 'x = y').where( '( m = n AND o = p )', 'f = g')
+		#        #=> WHERE ( a = a OR b = c ) AND ( c = d OR e = e ) AND x = y ( ( m = n AND o = p ) OR f = g )
+		def where *cond
+			@_where.push cond
+			self
+		end
+
+		def wobs vals
+			@_wobs.update vals
+			self
+		end
+
+		def quote_column_name name
+			@quoter.quote_column_name( name).gsub /"\."/, ','
+		end
+
+		def quote_table_name name
+			@quoter.quote_table_name( name).gsub /"\."/, ','
+		end
+
+		def column table, name
+			"#{quote_table_name table.kind_of?(String) ? table : @table_alias[table]}.#{quote_column_name name}"
+		end
+
+		def build_join orig, pretable, table, prekey, key
+			" JOIN #{quote_table_name orig.to_sym} AS #{quote_table_name table} ON #{column pretable, prekey} = #{column table, key} "
+		end
+
+		def join table, model
+			return self  if @_joined.include? table # Already joined
+			pretable = table[0...-1]
+			@table_model[ table] = model
+			premodel = @table_model[ pretable]
+			t = @table_alias[ table]
+			pt = quote_table_name @table_alias[ table[ 0...-1]]
+			refl = premodel.reflections[table.last]
+			case refl.macro
+			when :has_many
+				@_joins += build_join model.table_name, pretable, t, premodel.primary_key, refl.primary_key_name
+			when :belongs_to
+				@_joins += build_join model.table_name, pretable, t, refl.primary_key_name, premodel.primary_key
+			when :has_and_belongs_to_many
+				jointable = [','] + table
+				@_joins += build_join refl.options[:join_table], pretable, @table_alias[jointable], premodel.primary_key, refl.primary_key_name
+				@_joins += build_join model.table_name, jointable, t, refl.association_foreign_key, refl.association_primary_key
+			else raise BuilderError, "Unkown reflection macro: #{refl.macro.inspect}"
+			end
+			@_joined.push table
+			self
+		end
+
+		def includes table
+			@_includes.push table
+			self
+		end
+
+		def select col
+			@_select.push quote_column_name( @table_alias[col])
+			self
+		end
+
+		def order table, col, o
+			@_order.push "#{column table, col} #{:DESC == o ? :DESC : :ASC}"
+		end
+
+		class Dummy
+			def method_missing m, *a, &e
+				#p :dummy => m, :pars => a, :block => e
+				self
+			end
+		end
+
+		def build_ar
+			where_str = @_where.collect do |w|
+				w = Array.wrap w
+				1 == w.length ? w.first : "( #{w.join( ' OR ')} )"
+			end.join ' AND '
+			incls = {}
+			@_includes.each do |inc|
+				b = incls
+				inc[1..-1].collect {|rel| b = b[rel] ||= {} }
+			end
+			@logger.debug incls: incls, joins: @_joins
+			@model = @model.
+				select( @_select.join( ', ')).
+				joins( @_joins).
+				where( where_str, @_wobs).
+				order( @_order.join( ', ')).
+				includes( incls)
+		end
+
+		def fix_calculate
+			def @model.calculate operation, column_name, options = nil
+				options = options.try(:dup) || {}
+				options[:distinct] = true  unless options.except(:distinct).present?
+				column_name = klass.primary_key  unless column_name.present?
+				super operation, column_name, options
+			end
+			self
+		end
+
+		def to_ar
+			build_ar
+			fix_calculate
+			@model
+		end
+	end
+end