Module: Lore::Table_Selector

Defined in:
lib/lore/table_selector.rb

Overview

:nodoc:

Constant Summary collapse

@@logger = 
Lore.logger

Class Method Summary collapse

Class Method Details

.build_joined_query(accessor, query_string = '', joined_tables = []) ⇒ Object

Extracted, recursive method for building the JOIN-part of a SELECT query.



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# File 'lib/lore/table_selector.rb', line 16

def self.build_joined_query(accessor, query_string='', joined_tables=[])

  top_table        = accessor.table_name
  is_a_hierarchy   = accessor.get_joins()
  own_primary_keys = accessor.get_primary_keys()
  own_foreign_keys = accessor.get_foreign_keys()

  joined_accessors = (accessor.get_is_a_klasses).dup
  joined_accessors.update(accessor.get_aggregate_klasses)

  # predefine
  own_p_keys     = Hash.new
  foreign_p_keys = Hash.new
  on_string      = String.new
  field_counter  = 0

  is_a_hierarchy.each_pair { |foreign_table, foreign_base_tables|
    # JOIN base.table ON ( 
    if !(joined_tables.include?(foreign_table)) then

         foreign_p_keys = own_primary_keys[foreign_table]
         
         own_p_keys = own_foreign_keys[foreign_table]

         if !own_p_keys.nil? then
           
           joined_tables << foreign_table
           query_string << "\n JOIN #{foreign_table} on ("
           
           field_counter = 0
           on_string = ''
           foreign_p_keys.uniq.each { |foreign_field|
             
             # base.table.foreign_field = 
             on_string << "#{foreign_table}.#{foreign_field} = #{top_table}.#{own_p_keys[field_counter]}"
             # this.table.own_field
             
             if field_counter > 0 then   query_string << ", #{on_string}"
             else                        query_string << on_string
             end
             
             field_counter += 1
           } 
           
           query_string << ')'

         end
         
         # sub-joins of joined table:   
         query_string = build_joined_query(joined_accessors["#{top_table}.#{own_p_keys.first}"], 
                                           query_string, 
                                           joined_tables)
       end
  }
  return query_string
end