Solving conflicted joins and include find options

Take this example:

User.all(:conditions => "orders.total > 100 and line_items.state = 'open'", :joins => {:orders => :line_items}, :include => :orders)

You get the same join being added twice. Plus, I may not want to eager load line items also. Why not skip any joins that have already been added? Now you can cherry pick which associations to eager load without getting an SQL error. I accomplished this by modifying the add_joins! function to the following:

def add_joins
scope = scope(:find) if :auto == scope
            merged_joins = scope && scope[:joins] && joins ? merge_joins(scope[:joins], joins) : (joins || scope && scope[:joins])
            case merged_joins
            when Symbol, Hash, Array
              if array_of_strings?(merged_joins)
                merged_joins.each { |merged_join| sql << " #{merged_join} " unless sql.include?(merged_join) }
              else
                join_dependency = ActiveRecord::Associations::ClassMethods::InnerJoinDependency.new(self, merged_joins, nil)
                join_dependency.join_associations.each do |assoc|
                  join_sql = assoc.association_join
                  sql << " #{join_sql} " unless sql.include?(join_sql)
                end
              end
            when String
              sql << " #{merged_joins} " if merged_joins && !sql.include?(merged_joins)
            end
end

This just makes more sense and allows the include option to be used as a way to eager load associations instead of a way to create joins, if that makes sense.