Make sure we reset the connection_specification_name on

remove_connection

When calling `remove_connection` on a model, we delete the pool so we also
need to reset the `connection_specification_name` so it will fallback to
the parent.
This was the current behavior before rails 5, which will fallback to the
parent connection pool.

[fixes #24959]

Special thanks to @jrafanie for working with me on this fix.

1 files changed, 8 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/connection_handling.rb b/activerecord/lib/active_record/connection_handling.rb
index a628ee4dbd..0a69ad2c0e 100644
--- a/activerecord/lib/active_record/connection_handling.rb
+++ b/activerecord/lib/active_record/connection_handling.rb
@@ -95,7 +95,7 @@ module ActiveRecord
 
     # Return the specification name from the current class or its parent.
     def connection_specification_name
-      unless defined?(@connection_specification_name)
+      if !defined?(@connection_specification_name) || @connection_specification_name.nil?
         @connection_specification_name = self == Base ? "primary" : superclass.connection_specification_name
       end
       @connection_specification_name
@@ -133,6 +133,13 @@ module ActiveRecord
     end
 
     def remove_connection(name = connection_specification_name)
+      # if removing a connection that have a pool, we reset the
+      # connection_specification_name so it will use the parent
+      # pool.
+      if connection_handler.retrieve_connection_pool(name)
+        self.connection_specification_name = nil
+      end
+
       connection_handler.remove_connection(name)
     end