associative fix for #156

[Surt]

#156

What I did is:

• new methods to define the result as associative or not (non_associative, associative, reset_associative
• on the constructor I set the flag to the defined in config self::$_config[$this->_connection_name]['find_many_primary_id_as_key']
• on find_many check :
  • if there is a primary key on the result instance (we assume primary key is unique)
  • if we look for an associative result set or not. (defined by the new config param and the new methods (non_associative, associative, reset_associative)

So, the config dictates the behaviour to return or not associative keys. That behaviour could be changed during fluent query. If there isn't a primary key define it fallbacks to non associative result set.

[Surt]

With this commits is easy to fix the has_many_through
see below:

[Surt]

We must change in https://github.com/j4mie/paris/blob/master/paris.php#L128

   /**
         * Create instances of each row in the result and map
         * them to an associative array with the primary IDs as
         * the array keys.
         * @param array $rows
         * @return array
         */
        protected function _instances_with_id_as_key($rows) {
            $size = count($rows);
            $instances = array();
             for ($i = 0; $i < $size; $i++) {
                $row = $this->_create_instance_from_row($rows[$i]);
                $row = $this->_create_model_instance(row);
                $key = (isset($row->{$this->_instance_id_column}) && $this->_associative_results) ? $row->{$this->_instance_id_column} : $i;
                $instances[$key] = $row;
            }
            return $instances;
        }

And the last change, in Model, https://github.com/j4mie/paris/blob/master/paris.php#L388

       ->where("{$join_table_name}.{$key_to_base_table}", $this->$base_table_id_column)
       ->non_associative();

Until this patchs, Paris is broken on has_many_through, returning just 1 instance of multiple objects with the same id (the objects are pushed on the same key)

[treffynnon]

See issue #133