Arel: Implemented DB-aware NULL-safe comparison (#34451)

* Arel: Implemented DB-aware NULL-safe comparison

* Fixed where clause inversion for NULL-safe comparison

* Renaming "null_safe_eq" to "is_not_distinct_from", "null_safe_not_eq" to "is_distinct_from"

[Dmytro Shteflyuk + Rafael Mendonça França]

9 files changed, 354 insertions, 1 deletions

diff --git a/activerecord/test/cases/arel/visitors/ibm_db_test.rb b/activerecord/test/cases/arel/visitors/ibm_db_test.rb
index 7163cb34d3..2ddbec3266 100644
--- a/activerecord/test/cases/arel/visitors/ibm_db_test.rb
+++ b/activerecord/test/cases/arel/visitors/ibm_db_test.rb
@@ -29,6 +29,45 @@ module Arel
         sql = compile(stmt)
         sql.must_be_like "UPDATE \"users\" WHERE \"users\".\"id\" IN (SELECT \"users\".\"id\" FROM \"users\" FETCH FIRST 1 ROWS ONLY)"
       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
diff --git a/activerecord/test/cases/arel/visitors/informix_test.rb b/activerecord/test/cases/arel/visitors/informix_test.rb
index b0b031cca3..b6c2dd6ae7 100644
--- a/activerecord/test/cases/arel/visitors/informix_test.rb
+++ b/activerecord/test/cases/arel/visitors/informix_test.rb
@@ -54,6 +54,45 @@ module Arel
         sql = compile(stmt)
         sql.must_be_like 'SELECT FROM "posts" INNER JOIN "comments"'
       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 %{
+            CASE WHEN "users"."name" = 'Aaron Patterson' OR ("users"."name" IS NULL AND 'Aaron Patterson' IS NULL) THEN 0 ELSE 1 END = 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 %{
+            CASE WHEN "users"."first_name" = "users"."last_name" OR ("users"."first_name" IS NULL AND "users"."last_name" IS NULL) THEN 0 ELSE 1 END = 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 %{
+            CASE WHEN "users"."first_name" = "users"."last_name" OR ("users"."first_name" IS NULL AND "users"."last_name" IS NULL) THEN 0 ELSE 1 END = 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
diff --git a/activerecord/test/cases/arel/visitors/mssql_test.rb b/activerecord/test/cases/arel/visitors/mssql_test.rb
index 340376c3d6..74f34b4dad 100644
--- a/activerecord/test/cases/arel/visitors/mssql_test.rb
+++ b/activerecord/test/cases/arel/visitors/mssql_test.rb
@@ -94,6 +94,45 @@ module Arel
         sql = compile(stmt)
         sql.must_be_like "SELECT COUNT(1) as count_id FROM (SELECT _t.* FROM (SELECT ROW_NUMBER() OVER (ORDER BY ) as _row_num) as _t WHERE _row_num BETWEEN 1 AND 10) AS subquery"
       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 %{
+            EXISTS (VALUES ("users"."name") INTERSECT VALUES ('Aaron Patterson'))
+          }
+        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 %{
+            EXISTS (VALUES ("users"."first_name") INTERSECT VALUES ("users"."last_name"))
+          }
+        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 %{
+            NOT EXISTS (VALUES ("users"."first_name") INTERSECT VALUES ("users"."last_name"))
+          }
+        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
diff --git a/activerecord/test/cases/arel/visitors/mysql_test.rb b/activerecord/test/cases/arel/visitors/mysql_test.rb
index dae98b0583..5f37587957 100644
--- a/activerecord/test/cases/arel/visitors/mysql_test.rb
+++ b/activerecord/test/cases/arel/visitors/mysql_test.rb
@@ -65,6 +65,45 @@ module Arel
           }
         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 %{
+            "users"."name" <=> 'Aaron Patterson'
+          }
+        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 %{
+            "users"."first_name" <=> "users"."last_name"
+          }
+        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" <=> 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 %{
+            NOT "users"."first_name" <=> "users"."last_name"
+          }
+        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 %{ NOT "users"."name" <=> NULL }
+        end
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/arel/visitors/oracle12_test.rb b/activerecord/test/cases/arel/visitors/oracle12_test.rb
index 83a2ee36ca..4ce5cab4db 100644
--- a/activerecord/test/cases/arel/visitors/oracle12_test.rb
+++ b/activerecord/test/cases/arel/visitors/oracle12_test.rb
@@ -56,6 +56,45 @@ module Arel
           }
         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
diff --git a/activerecord/test/cases/arel/visitors/oracle_test.rb b/activerecord/test/cases/arel/visitors/oracle_test.rb
index e1dfe40cf9..893edc7f74 100644
--- a/activerecord/test/cases/arel/visitors/oracle_test.rb
+++ b/activerecord/test/cases/arel/visitors/oracle_test.rb
@@ -192,6 +192,45 @@ module Arel
           }
         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
diff --git a/activerecord/test/cases/arel/visitors/postgres_test.rb b/activerecord/test/cases/arel/visitors/postgres_test.rb
index f7f2c76b6f..0f9efb20b4 100644
--- a/activerecord/test/cases/arel/visitors/postgres_test.rb
+++ b/activerecord/test/cases/arel/visitors/postgres_test.rb
@@ -276,6 +276,45 @@ module Arel
           }
         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 %{
+            "users"."name" IS NOT DISTINCT FROM 'Aaron Patterson'
+          }
+        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 %{
+            "users"."first_name" IS NOT DISTINCT FROM "users"."last_name"
+          }
+        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 NOT DISTINCT FROM 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 %{
+            "users"."first_name" IS DISTINCT FROM "users"."last_name"
+          }
+        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 DISTINCT FROM NULL }
+        end
+      end
     end
   end
 end
diff --git a/activerecord/test/cases/arel/visitors/sqlite_test.rb b/activerecord/test/cases/arel/visitors/sqlite_test.rb
index 6650b6ff3a..ee4e07a675 100644
--- a/activerecord/test/cases/arel/visitors/sqlite_test.rb
+++ b/activerecord/test/cases/arel/visitors/sqlite_test.rb
@@ -6,7 +6,11 @@ module Arel
   module Visitors
     class SqliteTest < Arel::Spec
       before do
-        @visitor = SQLite.new Table.engine.connection_pool
+        @visitor = SQLite.new Table.engine.connection
+      end
+
+      def compile(node)
+        @visitor.accept(node, Collectors::SQLString.new).value
       end
 
       it "defaults limit to -1" do
@@ -27,6 +31,45 @@ module Arel
         node = Nodes::False.new()
         assert_equal "0", @visitor.accept(node, Collectors::SQLString.new).value
       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 %{
+            "users"."name" IS 'Aaron Patterson'
+          }
+        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 %{
+            "users"."first_name" IS "users"."last_name"
+          }
+        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 %{
+            "users"."first_name" IS NOT "users"."last_name"
+          }
+        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
diff --git a/activerecord/test/cases/arel/visitors/to_sql_test.rb b/activerecord/test/cases/arel/visitors/to_sql_test.rb
index 680c26a9ab..4bfa799a96 100644
--- a/activerecord/test/cases/arel/visitors/to_sql_test.rb
+++ b/activerecord/test/cases/arel/visitors/to_sql_test.rb
@@ -155,6 +155,43 @@ module Arel
         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 %{
+            CASE WHEN "users"."name" = 'Aaron Patterson' OR ("users"."name" IS NULL AND 'Aaron Patterson' IS NULL) THEN 0 ELSE 1 END = 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 %{
+            CASE WHEN "users"."first_name" = "users"."last_name" OR ("users"."first_name" IS NULL AND "users"."last_name" IS NULL) THEN 0 ELSE 1 END = 0
+          }
+        end
+
+        it "should handle nil" do
+          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 %{
+            CASE WHEN "users"."first_name" = "users"."last_name" OR ("users"."first_name" IS NULL AND "users"."last_name" IS NULL) THEN 0 ELSE 1 END = 1
+          }
+        end
+
+        it "should handle nil" do
+          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
+
       it "should visit string subclass" do
         [
           Class.new(String).new(":'("),