<?php
/**
 * eGroupWare generalized SQL Storage Object with build in custom field support
 *
 * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
 * @package etemplate
 * @link http://www.egroupware.org
 * @author Ralf Becker <RalfBecker@outdoor-training.de>
 * @copyright 2009 by RalfBecker@outdoor-training.de
 * @version $Id$
 */

/**
 * Generalized SQL Storage Object with build in custom field support
 *
 * This class allows to display, search, order and filter by custom fields simply by replacing so_sql
 * by it and adding custom field widgets to the eTemplates of an applications.
 * It's inspired by the code from Klaus Leithoff, which does the same thing limited to addressbook.
 *
 * The schema of the custom fields table should be like (the lenght of the cf name is nowhere enfored and
 * varies throughout eGW from 40-255, the value column from varchar(255) to longtext!):
 *
 * 'egw_app_extra' => array(
 * 	'fd' => array(
 * 		'prefix_id' => array('type' => 'int','precision' => '4','nullable' => False),
 * 		'prefix_name' => array('type' => 'string','precision' => '64','nullable' => False),
 * 		'prefix_value' => array('type' => 'text'),
 * 	),
 *  'pk' => array('prefix_id','prefix_name'),
 *	'fk' => array(),
 *	'ix' => array(),
 *	'uc' => array()
 * )
 *
 * @package etemplate
 * @subpackage api
 * @author RalfBecker-AT-outdoor-training.de
 * @license http://opensource.org/licenses/gpl-license.php GPL - GNU General Public License
 */
class so_sql_cf extends so_sql
{
	/**
	 * Prefix used by the class
	 */
	const CF_PREFIX = '#';

	/**
	 * name of customefields table
	 *
	 * @var string
	 */
	var $extra_table;

	/**
	 * name of id column, defaults to the regular tables auto id
	 *
	 * @var string
	 */
	var $extra_id = '_id';

	/**
	 * Name of key (cf name) column or just a postfix added to the table prefix
	 *
	 * @var string
	 */
	var $extra_key = '_name';

	/**
	 * Name of value column or just a postfix added to the table prefix
	 *
	 * @var string
	 */
	var $extra_value = '_value';

	var $extra_join;
	var $extra_join_order;
	var $extra_join_filter;

	/**
	 * Does extra table has a unique index (over id and name)
	 *
	 * @var boolean
	 */
	var $extra_has_unique_index;

	/**
	 * Custom fields of $app, read by the constructor
	 *
	 * @var array
	 */
	var $customfields;

	/**
	 * Do we allow AND store multiple values for a cf (1:N) relations
	 *
	 * @var boolean
	 */
	var $allow_multiple_values = false;

	/**
	 * constructor of the class
	 *
	 * Please note the different params compared to so_sql!
	 *
	 * @param string $app application name to load table schemas
	 * @param string $table name of the table to use
	 * @param string $extra_table name of the custom field table
	 * @param string $colum_prefix='' column prefix to automatic remove from the column-name, if the column name starts with it
	 * @param string $extra_key='_name' column name for cf name column (will be prefixed with colum prefix, if starting with _)
	 * @param string $extra_value='_value' column name for cf value column (will be prefixed with colum prefix, if starting with _)
	 * @param string $extra_id='_id' column name for cf id column (will be prefixed with colum prefix, if starting with _)
	 * @param egw_db $db=null database object, if not the one in $GLOBALS['egw']->db should be used, eg. for an other database
	 * @param boolean $no_clone=true can we avoid to clone the db-object, default yes (different from so_sql!)
	 * 	new code using appnames and foreach(select(...,$app) can set it to avoid an extra instance of the db object
	 * @param boolean $allow_multiple_values=false should we allow AND store multiple values (1:N relations)
	 * @param string $timestamp_type=null default null=leave them as is, 'ts'|'integer' use integer unix timestamps, 'object' use egw_time objects
	 */
	function __construct($app,$table,$extra_table,$column_prefix='',
		$extra_key='_name',$extra_value='_value',$extra_id='_id',
		$db=null,$no_clone=true,$allow_multiple_values=false,$timestamp_type=null)
	{
		// calling the so_sql constructor
		parent::__construct($app,$table,$db,$column_prefix,$no_clone,$timestamp_type);

		$this->allow_multiple_values = $allow_multiple_values;
		$this->extra_table = $extra_table;
		if (!$this->extra_id) $this->extra_id = $this->autoinc_id;	// default to auto id of regular table

		// if names from columns of extra table are only postfixes (starting with _), prepend column prefix
		if (!($prefix=$column_prefix))
		{
			list($prefix) = explode('_',$this->autoinc_id);
		}
		elseif(substr($prefix,-1) == '_')
		{
			$prefix = substr($prefix,0,-1);	// remove trailing underscore from column prefix parameter
		}
		foreach(array('extra_id','extra_key','extra_value') as $col)
		{
			$this->$col = $col_name = $$col;
			if ($col_name[0] == '_') $this->$col = $prefix . $$col;
		}
		// some sanity checks, maybe they should be active only for development
		if (!($extra_defs = $this->db->get_table_definitions($app,$extra_table)))
		{
			throw new egw_exception_wrong_parameter("extra table $extra_table is NOT defined!");
		}
		foreach(array('extra_id','extra_key','extra_value') as $col)
		{
			if (!$this->$col || !isset($extra_defs['fd'][$this->$col]))
			{
				throw new egw_exception_wrong_parameter("$col column $extra_table.{$this->$col} is NOT defined!");
			}
		}
		// check if our extra table has a unique index (if not we have to delete the old values, as replacing does not work!)
		$this->extra_has_unique_index = $extra_defs['pk'] || $extra_defs['uc'];

		// setting up our extra joins, now we know table and column names
		$this->extra_join = " LEFT JOIN $extra_table ON $table.$this->autoinc_id=$extra_table.$this->extra_id";
		$this->extra_join_order = " LEFT JOIN $extra_table extra_order ON $table.$this->autoinc_id=extra_order.$this->extra_id";
		$this->extra_join_filter = " JOIN $extra_table extra_filter ON $table.$this->autoinc_id=extra_filter.$this->extra_id";

		$this->customfields = config::get_customfields($app);
	}

	/**
	 * Read all customfields of the given id's
	 *
	 * @param int|array $ids one ore more id's
	 * @param array $field_names=null custom fields to read, default all
	 * @return array id => $this->cf_field(name) => value
	 */
	function read_customfields($ids,$field_names=null)
	{
		if (is_null($field_names)) $field_names = array_keys($this->customfields);

		foreach((array)$ids as $key => $id)
		{
			if (!(int)$id && is_array($ids)) unset($ids[$key]);
		}
		if (!$ids || !$field_names) return array();	// nothing to do

		$entries = array();
		foreach($this->db->select($this->extra_table,'*',array(
			$this->extra_id => $ids,
			$this->extra_key => $field_names,
		),__LINE__,__FILE__,false,'',$this->app) as $row)
		{
			$entry =& $entries[$row[$this->extra_id]];
			$field = $this->get_cf_field($row[$this->extra_key]);

			if ($this->allow_multiple_values && $this->is_multiple($row[$this->extra_key]))
			{
				$entry[$field][] = $row[$this->extra_value];
			}
			else
			{
				$entry[$field] = $row[$this->extra_value];
			}
		}
		return $entries;
	}

	/**
	* saves custom field data
	*
	* @param array $data data to save (cf's have to be prefixed with self::CF_PREFIX = #)
	* @return bool false on success, errornumber on failure
	*/
	function save_customfields($data)
	{
		foreach ((array)$this->customfields as $name => $options)
		{
			if (!isset($data[$field = $this->get_cf_field($name)])) continue;

			$where = array(
				$this->extra_id    => $data[$this->autoinc_id],
				$this->extra_key   => $name,
			);
			$is_multiple = $this->is_multiple($name);

			// we explicitly need to delete fields, if value is empty or field allows multiple values or we have no unique index
			if(empty($data[$field]) || $is_multiple || !$this->extra_has_unique_index)
			{
				$this->db->delete($this->extra_table,$where,__LINE__,__FILE__,$this->app);
				if (empty($data[$field])) continue;	// nothing else to do for empty values
			}
			foreach($is_multiple && !is_array($data[$field]) ? explode(',',$data[$field]) : (array)$data[$field] as $value)
			{
				if (!$this->db->insert($this->extra_table,array($this->extra_value => $value),$where,__LINE__,__FILE__,$this->app))
				{
					return $this->db->Errno;
				}
			}
		}
		return false;	// no error
	}

	/**
	 * merges in new values from the given new data-array
	 *
	 * reimplemented to also merge the customfields
	 *
	 * @param $new array in form col => new_value with values to set
	 */
	function data_merge($new)
	{
		parent::data_merge($new);

		if ($this->customfields)
		{
			foreach($this->customfields as $name => $data)
			{
				if (isset($new[$field = $this->get_cf_field($name)]))
				{
					$this->data[$field] = $new[$field];
				}
			}
		}
	}

	/**
	 * reads row matched by key and puts all cols in the data array
	 *
	 * reimplented to also read the custom fields
	 *
	 * @param array $keys array with keys in form internalName => value, may be a scalar value if only one key
	 * @param string|array $extra_cols string or array of strings to be added to the SELECT, eg. "count(*) as num"
	 * @param string $join sql to do a join, added as is after the table-name, eg. ", table2 WHERE x=y" or
	 * @return array|boolean data if row could be retrived else False
	 */
	function read($keys,$extra_cols='',$join='')
	{
		if (!parent::read($keys,$extra_cols,$join))
		{
			return false;
		}
		if (($id = (int)$this->data[$this->autoinc_id]) && $this->customfields &&
			($cfs = $this->read_customfields($id)))
		{
			$this->data = array_merge($this->data,$cfs[$id]);
		}
		return $this->data;
	}

	/**
	 * saves the content of data to the db
	 *
	 * reimplented to also save the custom fields
	 *
	 * @param array $keys if given $keys are copied to data before saveing => allows a save as
	 * @param string|array $extra_where=null extra where clause, eg. to check an etag, returns true if no affected rows!
	 * @return int|boolean 0 on success, or errno != 0 on error, or true if $extra_where is given and no rows affected
	 */
	function save($keys=null,$extra_where=null)
	{
		if (is_array($keys) && count($keys) && !isset($keys[0]))	// allow to use an etag, eg array('etag=etag+1')
		{
			$this->data_merge($keys);
			$keys = null;
		}
		$ret = parent::save($keys,$extra_where);

		if ($ret == 0 && $this->customfields)
		{
			$this->save_customfields($this->data);
		}
		return $ret;
	}

	/**
	 * deletes row representing keys in internal data or the supplied $keys if != null
	 *
	 * reimplented to also delete the custom fields
	 *
	 * @param array|int $keys=null if given array with col => value pairs to characterise the rows to delete, or integer autoinc id
	 * @param boolean $only_return_ids=false return $ids of delete call to db object, but not run it (can be used by extending classes!)
	 * @return int|array affected rows, should be 1 if ok, 0 if an error or array with id's if $only_return_ids
	 */
	function delete($keys=null,$only_return_ids=false)
	{
		if ($this->customfields || $only_return_ids)
		{
			$query = parent::delete($keys,true);
			// check if query contains more then the id's
			if (!isset($query[$this->autoinc_id]) || count($query) != 1)
			{
				foreach($this->db->select($this->table_name,$this->autoinc_id,$query,__LINE__,__FILE__,false,'',$this->app) as $row)
				{
					$ids[] = $row[$this->autoinc_id];
				}
				if (!$ids) return 0;	// no rows affected
			}
			else
			{
				$ids = (array)$query[$this->autoinc_id];
			}
			if ($only_return_ids) return $ids;
			$this->db->delete($this->extra_table,array($this->extra_id => $ids),__LINE__,__FILE__);
		}
		return parent::delete($keys);
	}

	/**
	 * query rows for the nextmatch widget
	 *
	 * Reimplemented to also read the custom fields (if enabled via $query['selectcols']).
	 *
	 * Please note: the name of the nextmatch-customfields has to be 'customfields'!
	 *
	 * @param array $query with keys 'start', 'search', 'order', 'sort', 'col_filter'
	 *	For other keys like 'filter', 'cat_id' you have to reimplement this method in a derived class.
	 * @param array &$rows returned rows/competitions
	 * @param array &$readonlys eg. to disable buttons based on acl, not use here, maybe in a derived class
	 * @param string $join='' sql to do a join, added as is after the table-name, eg. ", table2 WHERE x=y" or
	 *	"LEFT JOIN table2 ON (x=y)", Note: there's no quoting done on $join!
	 * @param boolean $need_full_no_count=false If true an unlimited query is run to determine the total number of rows, default false
	 * @param mixed $only_keys=false, see search
	 * @param string|array $extra_cols=array()
	 * @return int total number of rows
	 */
	function get_rows($query,&$rows,&$readonlys,$join='',$need_full_no_count=false,$only_keys=false,$extra_cols=array())
	{
		parent::get_rows($query,$rows,$readonlys,$join,$need_full_no_count,$only_keys,$extra_cols);

		$selectcols = $query['selectcols'] ? explode(',',$query['selectcols']) : array();

		if ($rows && $this->customfields && (!$selectcols || in_array('customfields',$selectcols)))
		{
			$id2keys = array();
			foreach($rows as $key => $row)
			{
				$id2keys[$row[$this->autoinc_id]] = $key;
			}
			// check if only certain cf's to show
			foreach($selectcols as $col)
			{
				if ($this->is_cf($col)) $fields[] = $this->get_cf_name($col);
			}
			if (($cfs = $this->read_customfields(array_keys($id2keys),$fields)))
			{
				foreach($cfs as $id => $data)
				{
					$rows[$id2keys[$id]] = array_merge($rows[$id2keys[$id]],$data);
				}
			}
		}
		return $this->total;
	}

	/**
	 * searches db for rows matching searchcriteria
	 *
	 * Reimplemented to search, order and filter by custom fields
	 *
	 * @param array|string $criteria array of key and data cols, OR string with search pattern (incl. * or ? as wildcards)
	 * @param boolean|string/array $only_keys=true True returns only keys, False returns all cols. or
	 *	comma seperated list or array of columns to return
	 * @param string $order_by='' fieldnames + {ASC|DESC} separated by colons ',', can also contain a GROUP BY (if it contains ORDER BY)
	 * @param string|array $extra_cols='' string or array of strings to be added to the SELECT, eg. "count(*) as num"
	 * @param string $wildcard='' appended befor and after each criteria
	 * @param boolean $empty=false False=empty criteria are ignored in query, True=empty have to be empty in row
	 * @param string $op='AND' defaults to 'AND', can be set to 'OR' too, then criteria's are OR'ed together
	 * @param mixed $start=false if != false, return only maxmatch rows begining with start, or array($start,$num), or 'UNION' for a part of a union query
	 * @param array $filter=null if set (!=null) col-data pairs, to be and-ed (!) into the query without wildcards
	 * @param string $join='' sql to do a join, added as is after the table-name, eg. "JOIN table2 ON x=y" or
	 *	"LEFT JOIN table2 ON (x=y AND z=o)", Note: there's no quoting done on $join, you are responsible for it!!!
	 * @param boolean $need_full_no_count=false If true an unlimited query is run to determine the total number of rows, default false
	 * @return array|NULL array of matching rows (the row is an array of the cols) or NULL
	 */
	function &search($criteria,$only_keys=True,$order_by='',$extra_cols='',$wildcard='',$empty=False,$op='AND',$start=false,$filter=null,$join='',$need_full_no_count=false)
	{
		if ($only_keys === false)
		{
			$only_keys = $this->table_name.'.*';
		}
		// if string given as criteria --> search in all (or $this->columns_to_search) columns including custom fields
		if ($criteria && is_string($criteria))
		{
			$criteria = $this->search2criteria($criteria,$wildcard,$op);
		}
		if ($criteria && is_array($criteria))
		{
			$join .= $this->extra_join;

			// check if we search in the custom fields
			if (isset($criteria[$this->extra_value]))
			{
				if (($negate = $criteria[$this->extra_value][0] === '!'))
				{
					$criteria[$this->extra_value] = substr($criteria[$this->extra_value],1);
				}
				$criteria[] = $this->extra_table.'.'.$this->extra_value . ' ' .($negate ? 'NOT ' : '').
					$this->db->capabilities[egw_db::CAPABILITY_CASE_INSENSITIV_LIKE]. ' ' .
					$this->db->quote($wildcard.$criteria[$this->extra_value].$wildcard);
				unset($criteria[$this->extra_value]);
			}
			// replace ambiguous auto-id with (an exact match of) table_name.autoid
			if (isset($criteria[$this->autoinc_id]))
			{
				if ($criteria[$this->autoinc_id])
				{
					$criteria[] = $this->db->expression($this->table_name,$this->table_name.'.',
						array($this->autoinc_id => $criteria[$this->autoinc_id]));
				}
				unset($criteria[$this->autoinc_id]);
			}
			// replace ambiguous column with (an exact match of) table_name.column
			foreach($criteria as $name => $val)
			{
				$extra_columns = $this->db->get_table_definitions($app, $this->extra_table);
				if(is_string($name) && $extra_columns['fd'][array_search($name, $this->db_cols)])
				{
					$criteria[] = $this->db->expression($this->table_name,$this->table_name.'.',array(
						array_search($name, $this->db_cols) => $val,
					));
					unset($criteria[$name]);
				}
				elseif (is_string($name) && $this->is_cf($name))
				{
					if ($op != 'AND')
					{
						$name = substr($name, 1);
						if (($negate = $criteria[$name][0] === '!'))
						{
							$val = substr($val,1);
						}
						$cfcriteria[] = '(' . $this->extra_table.'.'.$this->extra_value . ' ' .($negate ? 'NOT ' : '').
							$this->db->capabilities[egw_db::CAPABILITY_CASE_INSENSITIV_LIKE]. ' ' .
							$this->db->quote($wildcard.$val.$wildcard) . ' AND ' .
							$this->extra_table.'.'.$this->extra_key . ' = ' . $this->db->quote($name) .
							')';
						unset($criteria[self::CF_PREFIX.$name]);
					}
					else
					{
						// criteria operator is AND we remap the criteria to be transformed to filters
						$filter[$name] = $val;
						unset($criteria[$name]);
					}
				}
			}
			if ($cfcriteria && $op =='OR') $criteria[] = implode(' OR ',$cfcriteria);
		}
		if($only_keys === true) {
			// Expand to keys here, so table_name can be prepended below
			$only_keys = array_values($this->db_key_cols);
		}
		// replace ambiguous column with (an exact match of) table_name.column
		if(is_array($only_keys))
		{
			foreach($only_keys as $key => &$col)
			{
				if(is_numeric($key) && in_array($col, $this->db_cols))
				{
					$col = $this->table_name .'.'.array_search($col, $this->db_cols).' AS '.$col;
				}
			}
		}

		// check if we order by a custom field --> join cf table for given cf and order by it's value
		if (strpos($order_by,self::CF_PREFIX) !== false &&
			preg_match('/'.self::CF_PREFIX.'([^ ]+) (asc|desc)/i',$order_by,$matches))
		{
			$order_by = str_replace($matches[0],'extra_order.'.$this->extra_value.' IS NULL,extra_order.'.$this->extra_value.' '.$matches[2],$order_by);
			$join .= $this->extra_join_order.' AND extra_order.'.$this->extra_key.'='.$this->db->quote($matches[1]);
		}

		// check if we filter by a custom field
		if (is_array($filter))
		{
			foreach($filter as $name => $val)
			{
				// replace ambiguous auto-id with (an exact match of) table_name.autoid
				if (is_string($name) && $name == $this->autoinc_id)
				{
					if ((int)$filter[$this->autoinc_id])
					{
						$filter[] = $this->db->expression($this->table_name,$this->table_name.'.',array(
							$this->autoinc_id => $filter[$this->autoinc_id],
						));
					}
					unset($filter[$this->autoinc_id]);
				}
				// replace ambiguous column with (an exact match of) table_name.column
				elseif (is_string($name) && $val!=null && in_array($name, $this->db_cols))
				{
					$extra_columns = $this->db->get_table_definitions($app, $this->extra_table);
					if($extra_columns['fd'][array_search($name, $this->db_cols)]) {
						$filter[] = $this->db->expression($this->table_name,$this->table_name.'.',array(
							array_search($name, $this->db_cols) => $val,
						));
						unset($filter[$name]);
					}
				}
				elseif (is_string($name) && $this->is_cf($name))
				{
					if (!empty($val))	// empty -> dont filter
					{
						if ($val[0] === '!')	// negative filter
						{
							$sql_filter = 'extra_filter.'.$this->extra_value.'!='.$this->db->quote(substr($val,1));
						}
						else	// using egw_db::expression to allow to use array() with possible values or NULL
						{
							if($this->customfields[$this->get_cf_name($name)]['type'] == 'select' &&
								$this->customfields[$this->get_cf_name($name)]['rows'] > 1)
							{
								// Multi-select - any entry with the filter value selected matches
								$sql_filter = str_replace($this->extra_value,'extra_filter.'.
									$this->extra_value,$this->db->expression($this->extra_table,array(
										$this->db->concat("','",$this->extra_value,"','").' '.$this->db->capabilities[egw_db::CAPABILITY_CASE_INSENSITIV_LIKE].' '.$this->db->quote('%,'.$val.',%')
									))
								);
							}
							else
							{
								$sql_filter = str_replace($this->extra_value,'extra_filter.'.
									$this->extra_value,$this->db->expression($this->extra_table,array($this->extra_value => $val)));
							}
						}
						// need to use a LEFT JOIN for negative search or to allow NULL values
						$need_left_join = $val[0] === '!' || strpos($sql_filter,'IS NULL') !== false ? ' LEFT ' : '';
						$join .= str_replace('extra_filter','extra_filter'.$extra_filter,$need_left_join.$this->extra_join_filter.
							' AND extra_filter.'.$this->extra_key.'='.$this->db->quote($this->get_cf_name($name)).
							' AND '.$sql_filter);
						++$extra_filter;
					}
					unset($filter[$name]);
				}
				elseif(is_int($name) && $this->is_cf($val))	// lettersearch: #cfname LIKE 's%'
				{
					list($cf) = explode(' ',$val);
					$join .= str_replace('extra_filter','extra_filter'.$extra_filter,$this->extra_join_filter.
						' AND extra_filter.'.$this->extra_key.'='.$this->db->quote($this->get_cf_name($cf)).
						' AND '.str_replace($cf,'extra_filter.'.$this->extra_value,$val));
					++$extra_filter;
					unset($filter[$name]);
				}
			}
		}
		if (!empty($join) && !is_array($only_keys)) $only_keys = 'DISTINCT '.$only_keys;	// otherwise join returns rows more then once

		return parent::search($criteria,$only_keys,$order_by,$extra_cols,$wildcard,$empty,$op,$start,$filter,$join,$need_full_no_count);
	}

	/**
	 * Return criteria array for a given search pattern
	 * Reimplemented to search custom fields
	 *
	 * @param string $pattern search pattern incl. * or ? as wildcard, if no wildcards used we append and prepend one!
	 * @param string &$wildcard='' on return wildcard char to use, if pattern does not already contain wildcards!
	 * @param string &$op='AND' on return boolean operation to use, if pattern does not start with ! we use OR else AND
	 * @param string $extra_col=null extra column to search
	 * @param array $search_cols=array() List of columns to search.  If not provided, all columns in $this->db_cols will be considered
	 * @return array or column => value pairs
	 */
	public function search2criteria($pattern,&$wildcard='',&$op='AND',$extra_col=null, $search_cols = array())
	{
		// This function can get called multiple times.  Make sure it doesn't re-process.
		if (empty($pattern) || is_array($pattern)) return $pattern;
		if(strpos($pattern, 'CAST(COALESCE(') !== false)
		{
			return $pattern;
		}

		$pattern = trim($pattern);
		$filter = array();
		if(!$search_cols)
		{
			$search_cols = $this->get_default_search_columns();
		}

		// Add in custom field column, if it is not already there
		if(!in_array($this->extra_table.'.'.$this->extra_value, $search_cols))
		{
			$search_cols[] = $this->extra_table.'.'.$this->extra_value;
		}

		// Let parent deal with the normal stuff
		$criteria = parent::search2criteria($pattern, $wildcard, $op, $extra_col, $search_cols);

		return $criteria;
	}

	/**
	 * Function to test if $field is a custom field: check for the prefix
	 *
	 * @param string $field
	 * @return boolean true if $name is a custom field, false otherwise
	 */
	function is_cf($field)
	{
		return $field[0] == self::CF_PREFIX;
	}

	/**
	 * Get name part from a custom field: remove the prefix
	 *
	 * @param string $field
	 * @return string name without prefix
	 */
	function get_cf_name($field)
	{
		return substr($field,1);
	}

	/**
	 * Get the field-name from the name of a custom field: prepend the prefix
	 *
	 * @param string $name
	 * @return string prefix-name
	 */
	function get_cf_field($name)
	{
		return self::CF_PREFIX.$name;
	}

	/**
	 * Check if cf is stored as 1:N relation in DB and array in memory
	 *
	 * @param string $name
	 * @return string
	 */
	function is_multiple($name)
	{
		return $this->allow_multiple_values && in_array($this->customfields[$name]['type'],array('select','select-account')) &&
			$this->customfields[$name]['rows'] > 1;
	}

	/**
	 * Prevent someone calling the old php4 so_sql constructor
	 */
	function so_sql()
	{
		throw new egw_exception_assertion_failed('use __construct()!');
	}
}