From 378eb1484d9a01369174a7c2f606dbc90aa1bd86 Mon Sep 17 00:00:00 2001
From: Nicholas Jakobsen <nicholas.jakobsen@gmail.com>
Date: Thu, 22 May 2025 22:15:01 -0700
Subject: [PATCH] fix: Support time zone when serializing DateTimes

Previously a DateTime being serialized would ignore the timezone, effectively assuming the timezone of the value was the same as the column.

Instead, the timezone is now taken into account so the time can be given in any timezone and it will be converted to the timezone of the column.
---
 lib/click_house/type/date_time64_type.rb     |  8 ++++++--
 lib/click_house/type/date_time_type.rb       |  8 ++++++--
 spec/click_house/type/date_time64_spec.rb    | 17 +++++++++++++++--
 spec/click_house/type/date_time_type_spec.rb | 10 ++++++++++
 4 files changed, 37 insertions(+), 6 deletions(-)

diff --git a/lib/click_house/type/date_time64_type.rb b/lib/click_house/type/date_time64_type.rb
index dc802c8..fb9bdbd 100644
--- a/lib/click_house/type/date_time64_type.rb
+++ b/lib/click_house/type/date_time64_type.rb
@@ -32,8 +32,12 @@ def cast(value, precision = 0, tz = nil)
         end
       end
 
-      def serialize(value, precision = 3, _tz = nil)
-        value.strftime(SERIALIZE_FORMATS.fetch(precision))
+      def serialize(value, precision = 3, tz = nil)
+        if tz
+          value.in_time_zone(Time.find_zone(tz)).strftime(SERIALIZE_FORMATS.fetch(precision))
+        else
+          value.strftime(SERIALIZE_FORMATS.fetch(precision))
+        end
       end
     end
   end
diff --git a/lib/click_house/type/date_time_type.rb b/lib/click_house/type/date_time_type.rb
index e40767e..c9c429d 100644
--- a/lib/click_house/type/date_time_type.rb
+++ b/lib/click_house/type/date_time_type.rb
@@ -13,8 +13,12 @@ def cast(value, tz = nil)
         end
       end
 
-      def serialize(value, *)
-        value.strftime(FORMAT)
+      def serialize(value, tz = nil)
+        if tz
+          value.in_time_zone(Time.find_zone(tz)).strftime(FORMAT)
+        else
+          value.strftime(FORMAT)
+        end
       end
     end
   end
diff --git a/spec/click_house/type/date_time64_spec.rb b/spec/click_house/type/date_time64_spec.rb
index 8904873..ddb3ea8 100644
--- a/spec/click_house/type/date_time64_spec.rb
+++ b/spec/click_house/type/date_time64_spec.rb
@@ -1,5 +1,5 @@
 RSpec.describe ClickHouse::Type::DateTime64Type do
-  let(:precisions) do 
+  let(:precisions) do
     (0..9).to_a
   end
 
@@ -9,11 +9,24 @@
     end
 
     it 'works' do
-      precisions.each do |precision|        
+      precisions.each do |precision|
         tail = "." + "0" * precision if precision > 0
         expect(subject.serialize(time, precision)).to eq("2019-01-01 09:05:06#{tail}")
       end
     end
+
+    context 'when zone exists' do
+      let(:time) do
+        Time.new(2019, 1, 1, 9, 5, 6, Time.find_zone('UTC'))
+      end
+
+      it 'works' do
+        precisions.each do |precision|
+          tail = "." + "0" * precision if precision > 0
+          expect(subject.serialize(time, precision, 'Europe/Kyiv')).to eq("2019-01-01 11:05:06#{tail}")
+        end
+      end
+    end
   end
 
   describe '#cast' do
diff --git a/spec/click_house/type/date_time_type_spec.rb b/spec/click_house/type/date_time_type_spec.rb
index 78a5700..76b8c61 100644
--- a/spec/click_house/type/date_time_type_spec.rb
+++ b/spec/click_house/type/date_time_type_spec.rb
@@ -7,6 +7,16 @@
     it 'works' do
       expect(subject.serialize(time)).to eq('2019-01-01 09:05:06')
     end
+
+    context 'when zone exists' do
+      let(:time) do
+        Time.new(2019, 1, 1, 9, 5, 6, Time.find_zone('UTC'))
+      end
+
+      it 'works' do
+        expect(subject.serialize(time, 'Europe/Kyiv')).to eq('2019-01-01 11:05:06')
+      end
+    end
   end
 
   describe '#cast' do