Use the query lock hint when joining tables

Author: Aidan Haran

CHANGELOG.md

@@ -1,5 +1,9 @@
 ## v5.1.5
 
+#### Added
+
+* Use lock hint when joining table in query.
+
 #### Fixed
 
 * Memoize `@@version` queries. Fixes #632

lib/arel/visitors/sqlserver.rb

@@ -95,17 +95,29 @@ def visit_Arel_Nodes_JoinSource o, collector
           collector = visit_Arel_Nodes_SelectStatement_SQLServer_Lock collector
         end
         if o.right.any?
-          collector << " " if o.left
+          collector << SPACE if o.left
           collector = inject_join o.right, collector, ' '
         end
         collector
       end
 
+      def visit_Arel_Nodes_InnerJoin o, collector
+        collector << "INNER JOIN "
+        collector = visit o.left, collector
+        collector = visit_Arel_Nodes_SelectStatement_SQLServer_Lock collector, space: true
+        if o.right
+          collector << SPACE
+          visit(o.right, collector)
+        else
+          collector
+        end
+      end
+
       def visit_Arel_Nodes_OuterJoin o, collector
         collector << "LEFT OUTER JOIN "
         collector = visit o.left, collector
         collector = visit_Arel_Nodes_SelectStatement_SQLServer_Lock collector, space: true
-        collector << " "
+        collector << SPACE
         visit o.right, collector
       end
 

test/cases/pessimistic_locking_test_sqlserver.rb

@@ -52,6 +52,34 @@ class PessimisticLockingTestSQLServer < ActiveRecord::TestCase
       end
     end
 
+    describe 'joining tables' do
+
+      it 'joined tables use updlock by default' do
+        assert_sql %r|SELECT \[people\]\.\* FROM \[people\] WITH\(UPDLOCK\) INNER JOIN \[readers\] WITH\(UPDLOCK\)\s+ON \[readers\]\.\[person_id\] = \[people\]\.\[id\]| do
+          Person.lock(true).joins(:readers).load
+        end
+      end
+
+      it 'joined tables can use custom lock directive' do
+        assert_sql %r|SELECT \[people\]\.\* FROM \[people\] WITH\(NOLOCK\) INNER JOIN \[readers\] WITH\(NOLOCK\)\s+ON \[readers\]\.\[person_id\] = \[people\]\.\[id\]| do
+          Person.lock('WITH(NOLOCK)').joins(:readers).load
+        end
+      end
+
+      it 'left joined tables use updlock by default' do
+        assert_sql %r|SELECT \[people\]\.\* FROM \[people\] WITH\(UPDLOCK\) LEFT OUTER JOIN \[readers\] WITH\(UPDLOCK\)\s+ON \[readers\]\.\[person_id\] = \[people\]\.\[id\]| do
+          Person.lock(true).left_joins(:readers).load
+        end
+      end
+
+      it 'left joined tables can use custom lock directive' do
+        assert_sql %r|SELECT \[people\]\.\* FROM \[people\] WITH\(NOLOCK\) LEFT OUTER JOIN \[readers\] WITH\(NOLOCK\)\s+ON \[readers\]\.\[person_id\] = \[people\]\.\[id\]| do
+          Person.lock('WITH(NOLOCK)').left_joins(:readers).load
+        end
+      end
+
+    end
+
   end
 
   describe 'For paginated finds' do