Create an ActiveRecord::Relation in rails 6 with a different table

Question

I am trying to upgrade partitioned gem in order to use partitioning with Rails 6.1 (I am upgrading an existing Rails application).
I have managed to get everything to work, except for one part:
In partitioned gem, in order to query the partitioned table,
they would create a new relation with the "correct" arel_table (i.e - the actual partition table we want to query).

The following syntax worked with Rails 3.2:

    def self.from_partition(*partition_key_values)
      table_alias_name = partition_table_alias_name(*partition_key_values)
      return ActiveRecord::Relation.new(self, self.arel_table_from_key_values(partition_key_values, table_alias_name))
    end

Where self.arel_table_from_key_values(partition_key_values, table_alias_name) is an instance of Arel::Table pointing to the correct table name (partition).

I've updated the syntax to be:

    def self.from_partition(*partition_key_values)
      table_alias_name = partition_table_alias_name(*partition_key_values)
      return ActiveRecord::Relation.new(self, table: self.arel_table_from_key_values(partition_key_values, table_alias_name))
    end

The problem now is that when I try to run commands that worked in Rails 3.2 such as:

ItemLine.from_partition(11,1).find_by_code("1111")

I get errors such as undefined method `find_by_code' for #<ActiveRecord::Relation Or if I try to run

ItemLine.from_partition(11,1).last

I get: undefined local variable or method `implicit_order_column' for #<ActiveRecord::Relation

It seems like I am creating the relation in a wrong way.
What is the best/correct way to create an ActiveRecord::Relation with a different arel table in Rails 6.1?

Thanks!

Answer 1

After digging around in the source code of ActiveRecord,
I was able to solve it in the following way:

def self.from_partition(*partition_key_values)
  table_alias_name = partition_table_alias_name(*partition_key_values)
  table = self.arel_table_from_key_values(partition_key_values, table_alias_name)
  tm = ActiveRecord::TableMetadata.new(self,table)
  predicate_builder = ActiveRecord::PredicateBuilder.new(tm)
  return ActiveRecord::Relation.create(self, table: table, predicate_builder: predicate_builder)
end

I still need to run some tests on this solution, but so far so good! :-)