Merge Arel visitors

lib/active_record/connection_adapters/oracle_enhanced_adapter.rb

@@ -30,6 +30,8 @@
 # contribution.
 # portions Copyright 2005 Graham Jenkins
 
+require "arel/visitors/oracle"
+require "arel/visitors/oracle12"
 require "active_record/connection_adapters"
 require "active_record/connection_adapters/abstract_adapter"
 require "active_record/connection_adapters/statement_pool"

lib/arel/visitors/oracle.rb

@@ -0,0 +1,158 @@
+# frozen_string_literal: true
+
+module Arel # :nodoc: all
+  module Visitors
+    class Oracle < Arel::Visitors::ToSql
+      private
+        def visit_Arel_Nodes_SelectStatement(o, collector)
+          o = order_hacks(o)
+
+          # if need to select first records without ORDER BY and GROUP BY and without DISTINCT
+          # then can use simple ROWNUM in WHERE clause
+          if o.limit && o.orders.empty? && o.cores.first.groups.empty? && !o.offset && !o.cores.first.set_quantifier.class.to_s.match?(/Distinct/)
+            o.cores.last.wheres.push Nodes::LessThanOrEqual.new(
+              Nodes::SqlLiteral.new("ROWNUM"), o.limit.expr
+            )
+            return super
+          end
+
+          if o.limit && o.offset
+            o        = o.dup
+            limit    = o.limit.expr
+            offset   = o.offset
+            o.offset = nil
+            collector << "
+                SELECT * FROM (
+                  SELECT raw_sql_.*, rownum raw_rnum_
+                  FROM ("
+
+            collector = super(o, collector)
+
+            if offset.expr.is_a? Nodes::BindParam
+              collector << ") raw_sql_ WHERE rownum <= ("
+              collector = visit offset.expr, collector
+              collector << " + "
+              collector = visit limit, collector
+              collector << ") ) WHERE raw_rnum_ > "
+              collector = visit offset.expr, collector
+              return collector
+            else
+              collector << ") raw_sql_
+                  WHERE rownum <= #{offset.expr.to_i + limit}
+                )
+                WHERE "
+              return visit(offset, collector)
+            end
+          end
+
+          if o.limit
+            o       = o.dup
+            limit   = o.limit.expr
+            collector << "SELECT * FROM ("
+            collector = super(o, collector)
+            collector << ") WHERE ROWNUM <= "
+            return visit limit, collector
+          end
+
+          if o.offset
+            o        = o.dup
+            offset   = o.offset
+            o.offset = nil
+            collector << "SELECT * FROM (
+                  SELECT raw_sql_.*, rownum raw_rnum_
+                  FROM ("
+            collector = super(o, collector)
+            collector << ") raw_sql_
+                )
+                WHERE "
+            return visit offset, collector
+          end
+
+          super
+        end
+
+        def visit_Arel_Nodes_Limit(o, collector)
+          collector
+        end
+
+        def visit_Arel_Nodes_Offset(o, collector)
+          collector << "raw_rnum_ > "
+          visit o.expr, collector
+        end
+
+        def visit_Arel_Nodes_Except(o, collector)
+          collector << "( "
+          collector = infix_value o, collector, " MINUS "
+          collector << " )"
+        end
+
+        def visit_Arel_Nodes_UpdateStatement(o, collector)
+          # Oracle does not allow ORDER BY/LIMIT in UPDATEs.
+          if o.orders.any? && o.limit.nil?
+            # However, there is no harm in silently eating the ORDER BY clause if no LIMIT has been provided,
+            # otherwise let the user deal with the error
+            o = o.dup
+            o.orders = []
+          end
+
+          super
+        end
+
+        ###
+        # Hacks for the order clauses specific to Oracle
+        def order_hacks(o)
+          return o if o.orders.empty?
+          return o unless o.cores.any? do |core|
+            core.projections.any? do |projection|
+              /FIRST_VALUE/ === projection
+            end
+          end
+          # Previous version with join and split broke ORDER BY clause
+          # if it contained functions with several arguments (separated by ',').
+          #
+          # orders   = o.orders.map { |x| visit x }.join(', ').split(',')
+          orders   = o.orders.map do |x|
+            string = visit(x, Arel::Collectors::SQLString.new).value
+            if string.include?(",")
+              split_order_string(string)
+            else
+              string
+            end
+          end.flatten
+          o.orders = []
+          orders.each_with_index do |order, i|
+            o.orders <<
+              Nodes::SqlLiteral.new("alias_#{i}__#{' DESC' if /\bdesc$/i.match?(order)}")
+          end
+          o
+        end
+
+        # Split string by commas but count opening and closing brackets
+        # and ignore commas inside brackets.
+        def split_order_string(string)
+          array = []
+          i = 0
+          string.split(",").each do |part|
+            if array[i]
+              array[i] << "," << part
+            else
+              # to ensure that array[i] will be String and not Arel::Nodes::SqlLiteral
+              array[i] = part.to_s
+            end
+            i += 1 if array[i].count("(") == array[i].count(")")
+          end
+          array
+        end
+
+        def visit_Arel_Nodes_BindParam(o, collector)
+          collector.add_bind(o.value) { |i| ":a#{i}" }
+        end
+
+        def is_distinct_from(o, collector)
+          collector << "DECODE("
+          collector = visit [o.left, o.right, 0, 1], collector
+          collector << ")"
+        end
+    end
+  end
+end

lib/arel/visitors/oracle12.rb

@@ -0,0 +1,65 @@
+# frozen_string_literal: true
+
+module Arel # :nodoc: all
+  module Visitors
+    class Oracle12 < Arel::Visitors::ToSql
+      private
+        def visit_Arel_Nodes_SelectStatement(o, collector)
+          # Oracle does not allow LIMIT clause with select for update
+          if o.limit && o.lock
+            raise ArgumentError, <<~MSG
+              Combination of limit and lock is not supported. Because generated SQL statements
+              `SELECT FOR UPDATE and FETCH FIRST n ROWS` generates ORA-02014.
+            MSG
+          end
+          super
+        end
+
+        def visit_Arel_Nodes_SelectOptions(o, collector)
+          collector = maybe_visit o.offset, collector
+          collector = maybe_visit o.limit, collector
+          maybe_visit o.lock, collector
+        end
+
+        def visit_Arel_Nodes_Limit(o, collector)
+          collector << "FETCH FIRST "
+          collector = visit o.expr, collector
+          collector << " ROWS ONLY"
+        end
+
+        def visit_Arel_Nodes_Offset(o, collector)
+          collector << "OFFSET "
+          visit o.expr, collector
+          collector << " ROWS"
+        end
+
+        def visit_Arel_Nodes_Except(o, collector)
+          collector << "( "
+          collector = infix_value o, collector, " MINUS "
+          collector << " )"
+        end
+
+        def visit_Arel_Nodes_UpdateStatement(o, collector)
+          # Oracle does not allow ORDER BY/LIMIT in UPDATEs.
+          if o.orders.any? && o.limit.nil?
+            # However, there is no harm in silently eating the ORDER BY clause if no LIMIT has been provided,
+            # otherwise let the user deal with the error
+            o = o.dup
+            o.orders = []
+          end
+
+          super
+        end
+
+        def visit_Arel_Nodes_BindParam(o, collector)
+          collector.add_bind(o.value) { |i| ":a#{i}" }
+        end
+
+        def is_distinct_from(o, collector)
+          collector << "DECODE("
+          collector = visit [o.left, o.right, 0, 1], collector
+          collector << ")"
+        end
+    end
+  end
+end

test/cases/arel/visitors/oracle12_test.rb

@@ -0,0 +1,100 @@
+# frozen_string_literal: true
+
+require_relative "../helper"
+
+module Arel
+  module Visitors
+    class Oracle12Test < Arel::Spec
+      before do
+        @visitor = Oracle12.new Table.engine.connection
+        @table = Table.new(:users)
+      end
+
+      def compile(node)
+        @visitor.accept(node, Collectors::SQLString.new).value
+      end
+
+      it "modified except to be minus" do
+        left = Nodes::SqlLiteral.new("SELECT * FROM users WHERE age > 10")
+        right = Nodes::SqlLiteral.new("SELECT * FROM users WHERE age > 20")
+        sql = compile Nodes::Except.new(left, right)
+        sql.must_be_like %{
+          ( SELECT * FROM users WHERE age > 10 MINUS SELECT * FROM users WHERE age > 20 )
+        }
+      end
+
+      it "generates select options offset then limit" do
+        stmt = Nodes::SelectStatement.new
+        stmt.offset = Nodes::Offset.new(1)
+        stmt.limit = Nodes::Limit.new(10)
+        sql = compile(stmt)
+        sql.must_be_like "SELECT OFFSET 1 ROWS FETCH FIRST 10 ROWS ONLY"
+      end
+
+      describe "locking" do
+        it "generates ArgumentError if limit and lock are used" do
+          stmt = Nodes::SelectStatement.new
+          stmt.limit = Nodes::Limit.new(10)
+          stmt.lock = Nodes::Lock.new(Arel.sql("FOR UPDATE"))
+          assert_raises ArgumentError do
+            compile(stmt)
+          end
+        end
+
+        it "defaults to FOR UPDATE when locking" do
+          node = Nodes::Lock.new(Arel.sql("FOR UPDATE"))
+          compile(node).must_be_like "FOR UPDATE"
+        end
+      end
+
+      describe "Nodes::BindParam" do
+        it "increments each bind param" do
+          query = @table[:name].eq(Arel::Nodes::BindParam.new(1))
+            .and(@table[:id].eq(Arel::Nodes::BindParam.new(1)))
+          compile(query).must_be_like %{
+            "users"."name" = :a1 AND "users"."id" = :a2
+          }
+        end
+      end
+
+      describe "Nodes::IsNotDistinctFrom" do
+        it "should construct a valid generic SQL statement" do
+          test = Table.new(:users)[:name].is_not_distinct_from "Aaron Patterson"
+          compile(test).must_be_like %{
+            DECODE("users"."name", 'Aaron Patterson', 0, 1) = 0
+          }
+        end
+
+        it "should handle column names on both sides" do
+          test = Table.new(:users)[:first_name].is_not_distinct_from Table.new(:users)[:last_name]
+          compile(test).must_be_like %{
+            DECODE("users"."first_name", "users"."last_name", 0, 1) = 0
+          }
+        end
+
+        it "should handle nil" do
+          @table = Table.new(:users)
+          val = Nodes.build_quoted(nil, @table[:active])
+          sql = compile Nodes::IsNotDistinctFrom.new(@table[:name], val)
+          sql.must_be_like %{ "users"."name" IS NULL }
+        end
+      end
+
+      describe "Nodes::IsDistinctFrom" do
+        it "should handle column names on both sides" do
+          test = Table.new(:users)[:first_name].is_distinct_from Table.new(:users)[:last_name]
+          compile(test).must_be_like %{
+            DECODE("users"."first_name", "users"."last_name", 0, 1) = 1
+          }
+        end
+
+        it "should handle nil" do
+          @table = Table.new(:users)
+          val = Nodes.build_quoted(nil, @table[:active])
+          sql = compile Nodes::IsDistinctFrom.new(@table[:name], val)
+          sql.must_be_like %{ "users"."name" IS NOT NULL }
+        end
+      end
+    end
+  end
+end