Use matching current timestamp precision on AR 7.0+

Starting from Active Record 7.0, the precision of timestamp columns
defaults to 6, where it was previously undefined. MySQL requires that
the precision of the CURRENT_TIMESTAMP default value matches the column
type precision, otherwise it throws errors. So, we make that change.

Fixes #159

CHANGELOG.md

@@ -1,3 +1,7 @@
+## HEAD
+
+* Use matching precision for current timestamp default values in Active Record 7.0+ migrations on MySQL (@janko)
+
 ## 1.6.1 (2022-09-19)
 
 * Fix argument error when calling `RodauthMailer` in default configuration (@janko)

lib/generators/rodauth/migration_generator.rb

@@ -110,9 +110,19 @@ def default_primary_key_type
 
           def current_timestamp
             if ActiveRecord.version >= Gem::Version.new("5.0")
-              %(-> { "CURRENT_TIMESTAMP" })
+              %(-> { "#{current_timestamp_literal}" })
             else
-              %(OpenStruct.new(quoted_id: "CURRENT_TIMESTAMP"))
+              %(OpenStruct.new(quoted_id: "#{current_timestamp_literal}"))
+            end
+          end
+
+          # Active Record 7+ sets default precision to 6 for timestamp columns,
+          # so we need to ensure we match this when setting the default value.
+          def current_timestamp_literal
+            if ActiveRecord.version >= Gem::Version.new("7.0") && activerecord_adapter == "mysql2" && ActiveRecord::Base.connection.supports_datetime_with_precision?
+              "CURRENT_TIMESTAMP(6)"
+            else
+              "CURRENT_TIMESTAMP"
             end
           end
         else # Sequel