Take an Array of ActiveRecord::Relation objects, extract their WHERE clauses and join them via a SQL OR operator. Allows you to conditionally build the relations based on business rules.

gistfile1.rb

def merge_where_clause_with_or(relations)
  relations.map { |relation| relation.arel.where_clauses }.join(' OR ')
end

# Usage
model.where(merge_where_clause_with_or(array_of_relations))