Move array database type casting to the Array type

The case where we have a column object, but don't have a type cast
method involves type casting the default value when changing the schema.
We get one of the column definition structs instead. That is a case that
I'm trying to remove overall, but in the short term, we can achieve the
same behavior without needing to pass the adapter to the array type by
creating a fake type that proxies to the adapter.

1 files changed, 30 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb b/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb
index 4e7d472d97..b686e1e5ad 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/oid/array.rb
@@ -22,6 +22,14 @@ module ActiveRecord
             type_cast_array(value, :type_cast_from_user)
           end
 
+          def type_cast_for_database(value)
+            if value.is_a?(::Array)
+              cast_value_for_database(value)
+            else
+              super
+            end
+          end
+
           # Loads pg_array_parser if available. String parsing can be
           # performed quicker by a native extension, which will not create
           # a large amount of Ruby objects that will need to be garbage
@@ -43,6 +51,28 @@ module ActiveRecord
               @subtype.public_send(method, value)
             end
           end
+
+          def cast_value_for_database(value)
+            if value.is_a?(::Array)
+              casted_values = value.map { |item| cast_value_for_database(item) }
+              "{#{casted_values.join(',')}}"
+            else
+              quote_and_escape(subtype.type_cast_for_database(value))
+            end
+          end
+
+          ARRAY_ESCAPE = "\\" * 2 * 2 # escape the backslash twice for PG arrays
+
+          def quote_and_escape(value)
+            case value
+            when ::String
+              value = value.gsub(/\\/, ARRAY_ESCAPE)
+              value.gsub!(/"/,"\\\"")
+              %("#{value}")
+            when nil then "NULL"
+            else value
+            end
+          end
         end
       end
     end