[m6w6/pq-gateway] / lib / pq / Gateway / Table / Relations.php

<?php

namespace pq\Gateway\Table;

use \pq\Gateway\Table;

const RELATION_SQL = <<<SQL
select
         case att1.attname
         when att2.attname
                then att1.attname
                else substring(att1.attname from '^.*(?=_'||att2.attname||'$)')
         end          as "id"
        ,cl1.relname  as "foreignTable"
        ,att1.attname as "foreignColumn"
        ,cl2.relname  as "referencedTable"
        ,att2.attname as "referencedColumn"
from
     pg_constraint co
    ,pg_class      cl1
    ,pg_class      cl2
    ,pg_attribute  att1
    ,pg_attribute  att2
where
        (       cl1.relname = \$1
        or      cl2.relname = \$1)
and co.confrelid != 0
and co.conrelid   = cl1.oid
and co.conkey[1]  = att1.attnum and cl1.oid = att1.attrelid
and co.confrelid  = cl2.oid
and co.confkey[1] = att2.attnum and cl2.oid = att2.attrelid
order by 
         cl1.relname
        ,att1.attnum
SQL;

/**
 * A foreighn key implementation
 */
class Relations
{
        /**
         * @var array
         */
        protected $references;
        
        function __construct(Table $table) {
                $cache = $table->getMetadataCache();
                if (!($this->references = $cache->get("$table#relations"))) {
                        $table->getQueryExecutor()->execute(
                                new \pq\Query\Writer(RELATION_SQL, array($table->getName())),
                                function($result) use($table, $cache) {
                                        $this->references = $result->map(array(0,1), array(1,2,3,4), \pq\Result::FETCH_OBJECT);
                                        $cache->set("$table#relations", $this->references);
                                }
                        );
                }
        }
        
        function __isset($r) {
                return isset($this->references->$r);
        }
        
        function __get($r) {
                return $this->references->$r;
        }
        
        function __set($r, $v) {
                $this->references->$r = $v;
        }
        
        function __unset($r){
                unset($this->references->$r);
        }
}