ult'])){
                return call_user_func_array(self::$_config[$connection_name]['cache_query_result'], array($cache_key, $value, $table_name, $connection_name));
            } elseif (!isset(self::$_query_cache[$connection_name])) {
                self::$_query_cache[$connection_name] = array();
            }
            self::$_query_cache[$connection_name][$cache_key] = $value;
        }

        /**
         * Execute the SELECT query that has been built up by chaining methods
         * on this class. Return an array of rows as associative arrays.
         */
        protected function _run() {
            $query = $this->_build_select();
            $caching_enabled = self::$_config[$this->_connection_name]['caching'];

            if ($caching_enabled) {
                $cache_key = self::_create_cache_key($query, $this->_values, $this->_table_name, $this->_connection_name);
                $cached_result = self::_check_query_cache($cache_key, $this->_table_name, $this->_connection_name);

                if ($cached_result !== false) {
                    $this->_reset_idiorm_state();
                    return $cached_result;
                }
            }

            self::_execute($query, $this->_values, $this->_connection_name);
            $statement = self::get_last_statement();

            $rows = array();
            while ($row = $statement->fetch(PDO::FETCH_ASSOC)) {
                $rows[] = $row;
            }

            if ($caching_enabled) {
                self::_cache_query_result($cache_key, $rows, $this->_table_name, $this->_connection_name);
            }

            $this->_reset_idiorm_state();
            return $rows;
        }

        /**
         * Reset the Idiorm instance state
         */
        private function _reset_idiorm_state() {
            $this->_values = array();
            $this->_result_columns = array('*');
            $this->_using_default_result_columns = true;
        }

        /**
         * Return the raw data wrapped by this ORM
         * instance as an associative array. Column
         * names may optionally be supplied as arguments,
         * if so, only those keys will be returned.
         */
        public function as_array() {
            if (func_num_args() === 0) {
                return $this->_data;
            }
            $args = func_get_args();
            return array_intersect_key($this->_data, array_flip($args));
        }

        /**
         * Return the value of a property of this object (database row)
         * or null if not present.
         *
         * If a column-names array is passed, it will return a associative array
         * with the value of each column or null if it is not present.
         */
        public function get($key) {
            if (is_array($key)) {
                $result = array();
                foreach($key as $column) {
                    $result[$column] = isset($this->_data[$column]) ? $this->_data[$column] : null;
                }
                return $result;
            } else {
                return isset($this->_data[$key]) ? $this->_data[$key] : null;
            }
        }

        /**
         * Return the name of the column in the database table which contains
         * the primary key ID of the row.
         */
        protected function _get_id_column_name() {
            if (!is_null($this->_instance_id_column)) {
                return $this->_instance_id_column;
            }
            if (isset(self::$_config[$this->_connection_name]['id_column_overrides'][$this->_table_name])) {
                return self::$_config[$this->_connection_name]['id_column_overrides'][$this->_table_name];
            }
            return self::$_config[$this->_connection_name]['id_column'];
        }

        /**
         * Get the primary key ID of this object.
         */
        public function id($disallow_null = false) {
            $id = $this->get($this->_get_id_column_name());

            if ($disallow_null) {
                if (is_array($id)) {
                    foreach ($id as $id_part) {
                        if ($id_part === null) {
                            throw new Exception('Primary key ID contains null value(s)');
                        }
                    }
                } else if ($id === null) {
                    throw new Exception('Primary key ID missing from row or is null');
                }
            }

            return $id;
        }

        /**
         * Set a property to a particular value on this object.
         * To set multiple properties at once, pass an associative array
         * as the first parameter and leave out the second parameter.
         * Flags the properties as 'dirty' so they will be saved to the
         * database when save() is called.
         */
        public function set($key, $value = null) {
            return $this->_set_orm_property($key, $value);
        }

        /**
         * Set a property to a particular value on this object.
         * To set multiple properties at once, pass an associative array
         * as the first parameter and leave out the second parameter.
         * Flags the properties as 'dirty' so they will be saved to the
         * database when save() is called.
         * @param string|array $key
         * @param string|null $value
         */
        public function set_expr($key, $value = null) {
            return $this->_set_orm_property($key, $value, true);
        }

        /**
         * Set a property on the ORM object.
         * @param string|array $key
         * @param string|null $value
         * @param bool $raw Whether this value should be treated as raw or not
         */
        protected function _set_orm_property($key, $value = null, $expr = false) {
            if (!is_array($key)) {
                $key = array($key => $value);
            }
            foreach ($key as $field => $value) {
                $this->_data[$field] = $value;
                $this->_dirty_fields[$field] = $value;
                if (false === $expr and isset($this->_expr_fields[$field])) {
                    unset($this->_expr_fields[$field]);
                } else if (true === $expr) {
                    $this->_expr_fields[$field] = true;
                }
            }
            return $this;
        }

        /**
         * Check whether the given field has been changed since this
         * object was saved.
         */
        public function is_dirty($key) {
            return array_key_exists($key, $this->_dirty_fields);
        }

        /**
         * Check whether the model was the result of a call to create() or not
         * @return bool
         */
        public function is_new() {
            return $this->_is_new;
        }

        /**
         * Save any fields which have been modified on this object
         * to the database.
         */
        public function save() {
            $query = array();

            // remove any expression fields as they are already baked into the query
            $values = array_values(array_diff_key($this->_dirty_fields, $this->_expr_fields));

            if (!$this->_is_new) { // UPDATE
                // If there are no dirty values, do nothing
                if (empty($values) && empty($this->_expr_fields)) {
                    return true;
                }
                $query = $this->_build_update();
                $id = $this->id(true);
                if (is_array($id)) {
                    $values = array_merge($values, array_values($id));
                } else {
                    $values[] = $id;
                }
            } else { // INSERT
                $query = $this->_build_insert();
            }

            $success = self::_execute($query, $values, $this->_connection_name);
            $caching_auto_clear_enabled = self::$_config[$this->_connection_name]['caching_auto_clear'];
            if($caching_auto_clear_enabled){
                self::clear_cache($this->_table_name, $this->_connection_name);
            }
            // If we've just inserted a new record, set the ID of this object
            if ($this->_is_new) {
                $this->_is_new = false;
                if ($this->count_null_id_columns() != 0) {
                    $db = self::get_db($this->_connection_name);
                    if($db->getAttribute(PDO::ATTR_DRIVER_NAME) == 'pgsql') {
                        // it may return several columns if a compound primary
                        // key is used
                        $row = self::get_last_statement()->fetch(PDO::FETCH_ASSOC);
                        foreach($row as $key => $value) {
                            $this->_data[$key] = $value;
                        }
                    } else {
                        $column = $this->_get_id_column_name();
                        // if the primary key is compound, assign the last inserted id
                        // to the first column
                        if (is_array($column)) {
                            $column = reset($column);
                        }
                        $this->_data[$column] = $db->lastInsertId();
                    }
                }
            }

            $this->_dirty_fields = $this->_expr_fields = array();
            return $success;
        }

        /**
         * Add a WHERE clause for every column that belongs to the primary key
         */
        public function _add_id_column_conditions(&$query) {
            $query[] = "WHERE";
            $keys = is_array($this->_get_id_column_name()) ? $this->_get_id_column_name() : array( $this->_get_id_column_name() );
            $first = true;
            foreach($keys as $key) {
                if ($first) {
                    $first = false;
                }
                else {
                    $query[] = "AND";
                }
                $query[] = $this->_quote_identifier($key);
                $query[] = "= ?";
            }
        }

        /**
         * Build an UPDATE query
         */
        protected function _build_update() {
            $query = array();
            $query[] = "UPDATE {$this->_quote_identifier($this->_table_name)} SET";

            $field_list = array();
            foreach ($this->_dirty_fields as $key => $value) {
                if(!array_key_exists($key, $this->_expr_fields)) {
                    $value = '?';
                }
                $field_list[] = "{$this->_quote_identifier($key)} = $value";
            }
            $query[] = implode(', ', $field_list);
            $this->_add_id_column_conditions($query);
            return implode(' ', $query);
        }

        /**
         * Build an INSERT query
         */
        protected function _build_insert() {
            $query[] = "INSERT INTO";
            $query[] = $this->_quote_identifier($this->_table_name);
            $field_list = array_map(array($this, '_quote_identifier'), array_keys($this->_dirty_fields));
            $query[] = "(" . implode(', ', $field_list) . ")";
            $query[] = "VALUES";

            $placeholders = $this->_create_placeholders($this->_dirty_fields);
            $query[] = "({$placeholders})";

            if (self::get_db($this->_connection_name)->getAttribute(PDO::ATTR_DRIVER_NAME) == 'pgsql') {
                $query[] = 'RETURNING ' . $this->_quote_identifier($this->_get_id_column_name());
            }

            return implode(' ', $query);
        }

        /**
         * Delete this record from the database
         */
        public function delete() {
            $query = array(
                "DELETE FROM",
                $this->_quote_identifier($this->_table_name)
            );
            $this->_add_id_column_conditions($query);
            return self::_execute(implode(' ', $query), is_array($this->id(true)) ? array_values($this->id(true)) : array($this->id(true)), $this->_connection_name);
        }

        /**
         * Delete many records from the database
         */
        public function delete_many() {
            // Build and return the full DELETE statement by concatenating
            // the results of calling each separate builder method.
            $query = $this->_join_if_not_empty(" ", array(
                "DELETE FROM",
                $this->_quote_identifier($this->_table_name),
                $this->_build_where(),
            ));

            return self::_execute($query, $this->_values, $this->_connection_name);
        }

        // --------------------- //
        // ---  ArrayAccess  --- //
        // --------------------- //

        public function offsetExists($key): bool {
            return array_key_exists($key, $this->_data);
        }

        #[\ReturnTypeWillChange] // Need to use annotation since mixed was added in 8.0
        public function offsetGet($key) {
            return $this->get($key);
        }

        public function offsetSet($key, $value): void {
            if(is_null($key)) {
                throw new InvalidArgumentException('You must specify a key/array index.');
            }
            $this->set($key, $value);
        }

        public function offsetUnset($key): void {
            unset($this->_data[$key]);
            unset($this->_dirty_fields[$key]);
        }

        // --------------------- //
        // --- MAGIC METHODS --- //
        // --------------------- //
        public function __get($key) {
            return $this->offsetGet($key);
        }

        public function __set($key, $value) {
            $this->offsetSet($key, $value);
        }

        public function __unset($key) {
            $this->offsetUnset($key);
        }


        public function __isset($key) {
            return $this->offsetExists($key);
        }

        /**
         * Magic method to capture calls to undefined class methods.
         * In this case we are attempting to convert camel case formatted
         * methods into underscore formatted methods.
         *
         * This allows us to call ORM methods using camel case and remain
         * backwards compatible.
         *
         * @param  string   $name
         * @param  array    $arguments
         * @return ORM
         */
        public function __call($name, $arguments)
        {
            $method = strtolower(preg_replace('/([a-z])([A-Z])/', '$1_$2', $name));

            if (method_exists($this, $method)) {
                return call_user_func_array(array($this, $method), $arguments);
            } else {
                throw new IdiormMethodMissingException("Method $name() does not exist in class " . get_class($this));
            }
        }

        /**
         * Magic method to capture calls to undefined static class methods.
         * In this case we are attempting to convert camel case formatted
         * methods into underscore formatted methods.
         *
         * This allows us to call ORM methods using camel case and remain
         * backwards compatible.
         *
         * @param  string   $name
         * @param  array    $arguments
         * @return ORM
         */
        public static function __callStatic($name, $arguments)
        {
            $method = strtolower(preg_replace('/([a-z])([A-Z])/', '$1_$2', $name));

            return call_user_func_array(array('MailPoetVendor\Idiorm\ORM', $method), $arguments);
        }
    }

    /**
     * A class to handle str_replace operations that involve quoted strings
     * @example IdiormString::str_replace_outside_quotes('?', '%s', 'columnA = "Hello?" AND columnB = ?');
     * @example IdiormString::value('columnA = "Hello?" AND columnB = ?')->replace_outside_quotes('?', '%s');
     * @author Jeff Roberson <ridgerunner@fluxbb.org>
     * @author Simon Holywell <treffynnon@php.net>
     * @link http://stackoverflow.com/a/13370709/461813 StackOverflow answer
     */
    class IdiormString {
        protected $subject;
        protected $search;
        protected $replace;

        /**
         * Get an easy to use instance of the class
         * @param string $subject
         * @return \self
         */
        public static function value($subject) {
            return new self($subject);
        }

        /**
         * Shortcut method: Replace all occurrences of the search string with the replacement
         * string where they appear outside quotes.
         * @param string $search
         * @param string $replace
         * @param string $subject
         * @return string
         */
        public static function str_replace_outside_quotes($search, $replace, $subject) {
            return self::value($subject)->replace_outside_quotes($search, $replace);
        }

        /**
         * Set the base string object
         * @param string $subject
         */
        public function __construct($subject) {
            $this->subject = (string) $subject;
        }

        /**
         * Replace all occurrences of the search string with the replacement
         * string where they appear outside quotes
         * @param string $search
         * @param string $replace
         * @return string
         */
        public function replace_outside_quotes($search, $replace) {
            $this->search = $search;
            $this->replace = $replace;
            return $this->_str_replace_outside_quotes();
        }

        /**
         * Validate an input string and perform a replace on all ocurrences
         * of $this->search with $this->replace
         * @author Jeff Roberson <ridgerunner@fluxbb.org>
         * @link http://stackoverflow.com/a/13370709/461813 StackOverflow answer
         * @return string
         */
        protected function _str_replace_outside_quotes(){
            $re_valid = '/
                # Validate string having embedded quoted substrings.
                ^                           # Anchor to start of string.
                (?:                         # Zero or more string chunks.
                  "[^"\\\\]*(?:\\\\.[^"\\\\]*)*"  # Either a double quoted chunk,
                | \'[^\'\\\\]*(?:\\\\.[^\'\\\\]*)*\'  # or a single quoted chunk,
                | [^\'"\\\\]+               # or an unquoted chunk (no escapes).
                )*                          # Zero or more string chunks.
                \z                          # Anchor to end of string.
                /sx';
            if (!preg_match($re_valid, $this->subject)) {
                throw new IdiormStringException("Subject string is not valid in the replace_outside_quotes context.");
            }
            $re_parse = '/
                # Match one chunk of a valid string having embedded quoted substrings.
                  (                         # Either $1: Quoted chunk.
                    "[^"\\\\]*(?:\\\\.[^"\\\\]*)*"  # Either a double quoted chunk,
                  | \'[^\'\\\\]*(?:\\\\.[^\'\\\\]*)*\'  # or a single quoted chunk.
                  )                         # End $1: Quoted chunk.
                | ([^\'"\\\\]+)             # or $2: an unquoted chunk (no escapes).
                /sx';
            return preg_replace_callback($re_parse, array($this, '_str_replace_outside_quotes_cb'), $this->subject);
        }

        /**
         * Process each matching chunk from preg_replace_callback replacing
         * each occurrence of $this->search with $this->replace
         * @author Jeff Roberson <ridgerunner@fluxbb.org>
         * @link http://stackoverflow.com/a/13370709/461813 StackOverflow answer
         * @param array $matches
         * @return string
         */
        protected function _str_replace_outside_quotes_cb($matches) {
            // Return quoted string chunks (in group $1) unaltered.
            if ($matches[1]) return $matches[1];
            // Process only unquoted chunks (in group $2).
            return preg_replace('/'. preg_quote($this->search, '/') .'/',
                $this->replace, $matches[2]);
        }
    }

    /**
     * A result set class for working with collections of model instances
     * @author Simon Holywell <treffynnon@php.net>
     * @method null setResults(array $results)
     * @method array getResults()
     */
    class IdiormResultSet implements Countable, IteratorAggregate, ArrayAccess {
        /**
         * The current result set as an array
         * @var array
         */
        protected $_results = array();

        /**
         * Optionally set the contents of the result set by passing in array
         * @param array $results
         */
        public function __construct(array $results = array()) {
            $this->set_results($results);
        }

        /**
         * Set the contents of the result set by passing in array
         * @param array $results
         */
        public function set_results(array $results) {
            $this->_results = $results;
        }

        /**
         * Get the current result set as an array
         * @return array
         */
        public function get_results() {
            return $this->_results;
        }

        /**
         * Get the current result set as an array
         * @return array
         */
        public function as_array() {
            return $this->get_results();
        }

        /**
         * Get the number of records in the result set
         * @return int
         */
        public function count(): int {
            return count($this->_results);
        }

        /**
         * Get an iterator for this object. In this case it supports foreaching
         * over the result set.
         * @return \ArrayIterator
         */
        public function getIterator(): \Traversable {
            return new ArrayIterator($this->_results);
        }

        /**
         * ArrayAccess
         * @param int|string $offset
         * @return bool
         */
        public function offsetExists($offset): bool {
            return isset($this->_results[$offset]);
        }

        /**
         * ArrayAccess
         * @param int|string $offset
         * @return mixed
         */
        #[\ReturnTypeWillChange] // Can't use mixed return typehint since it was added in 8.0
        public function offsetGet($offset) {
            return $this->_results[$offset];
        }

        /**
         * ArrayAccess
         * @param int|string $offset
         * @param mixed $value
         */
        public function offsetSet($offset, $value): void {
            $this->_results[$offset] = $value;
        }

        /**
         * ArrayAccess
         * @param int|string $offset
         */
        public function offsetUnset($offset): void {
            unset($this->_results[$offset]);
        }

        /**
         * Serializable
         * @return string
         */
        public function serialize() {
            return serialize($this->_results);
        }

        public function __serialize() {
          return $this->serialize();
        }

        /**
         * Serializable
         * @param string $serialized
         * @return array
         */
        public function unserialize($serialized) {
            return unserialize($serialized);
        }

        public function __unserialize($serialized) {
          return $this->unserialize($serialized);
        }

        /**
         * Call a method on all models in a result set. This allows for method
         * chaining such as setting a property on all models in a result set or
         * any other batch operation across models.
         * @example ORM::for_table('Widget')->find_many()->set('field', 'value')->save();
         * @param string $method
         * @param array $params
         * @return IdiormResultSet
         */
        public function __call($method, $params = array()) {
            foreach($this->_results as $model) {
                if (method_exists($model, $method)) {
                    call_user_func_array(array($model, $method), $params);
                } else {
                    throw new IdiormMethodMissingException("Method $method() does not exist in class " . get_class($this));
                }
            }
            return $this;
        }
    }

    /**
     * A placeholder for exceptions eminating from the IdiormString class
     */
    class IdiormStringException extends Exception {}

    class IdiormMethodMissingException extends Exception {}