Fixed error around DST for group_by_week and day_start with PostgreSQL

ankane · Feb 8, 2020 · a786b2d · a786b2d
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 4.3.1 (unreleased)
+
+- Fixed error around DST for `group_by_week` and `day_start` with PostgreSQL
+
 ## 4.3.0 (2019-12-26)
 
 - Fixed error with empty results in Ruby 2.7

diff --git a/LICENSE.txt b/LICENSE.txt
@@ -1,4 +1,4 @@
-Copyright (c) 2013-2019 Andrew Kane
+Copyright (c) 2013-2020 Andrew Kane
 
 MIT License
 

diff --git a/lib/groupdate/relation_builder.rb b/lib/groupdate/relation_builder.rb
@@ -79,11 +79,8 @@ def group_clause
           when :month_of_year
             ["EXTRACT(MONTH from #{column}::timestamptz AT TIME ZONE ? - INTERVAL '#{day_start} second')::integer", time_zone]
           when :week # start on Sunday, not PostgreSQL default Monday
-
-            # TODO apply time zone conversions before day subtraction?
-            # ["DATE_TRUNC('week', #{column}::timestamptz AT TIME ZONE ? - INTERVAL '#{week_start} day' - INTERVAL '#{day_start} second') AT TIME ZONE ? + INTERVAL '#{week_start} day' + INTERVAL '#{day_start} second'", time_zone, time_zone]
-
-            ["(DATE_TRUNC('week', (#{column}::timestamptz - INTERVAL '#{week_start} day' - INTERVAL '#{day_start} second') AT TIME ZONE ?) + INTERVAL '#{week_start} day' + INTERVAL '#{day_start} second') AT TIME ZONE ?", time_zone, time_zone]
+            # TODO just subtract number of days from day of week like MySQL?
+            ["DATE_TRUNC('week', #{column}::timestamptz AT TIME ZONE ? - INTERVAL '#{day_start} second' - INTERVAL '#{week_start} day') AT TIME ZONE ? + INTERVAL '#{week_start} day' + INTERVAL '#{day_start} second'", time_zone, time_zone]
           else
             ["DATE_TRUNC(?, #{column}::timestamptz AT TIME ZONE ? - INTERVAL '#{day_start} second') AT TIME ZONE ? + INTERVAL '#{day_start} second'", period, time_zone, time_zone]
           end

diff --git a/test/basic_test.rb b/test/basic_test.rb
@@ -79,19 +79,25 @@ def test_week_middle_of_week_with_time_zone_frequently
     # before and after DST weeks
     weeks = ["2013-03-03", "2013-03-10", "2013-03-17", "2013-10-27", "2013-11-03", "2013-11-10"]
     weekdays = [:sun, :mon, :tue, :wed, :thu, :fri, :sat]
-
-    weekdays.each_with_index do |week_start, i|
-      weeks.each do |week|
-        start_at = pt.parse(week) + i.days
-        time = start_at.dup
-        end_at = time + 1.week
-        while time < end_at
-          # prevent mysql error
-          if time.utc.to_s != "2013-03-10 02:00:00 UTC"
-            assert_result_date :week, start_at.strftime("%Y-%m-%d"), time.utc.to_s, true, week_start: week_start
-            User.delete_all
+    hours = [0, 1, 2, 3, 21, 22]
+
+    hours.each do |hour|
+      puts hour
+      weekdays.each_with_index do |week_start, i|
+        puts week_start
+        weeks.each do |week|
+          puts week
+          start_at = (pt.parse(week) + i.days).change(hour: hour)
+          time = start_at.dup
+          end_at = (time + 1.week).change(hour: hour)
+          while time < end_at
+            # prevent mysql error
+            if time.utc.to_s != "2013-03-10 02:00:00 UTC"
+              assert_result_date :week, start_at.strftime("%Y-%m-%d"), time.utc.to_s, true, week_start: week_start, day_start: hour
+              User.delete_all
+            end
+            time += 1.hour
           end
-          time += 1.hour
         end
       end
     end