silverstripe-framework/model/ManyManyList.php

<?php

/**
 * Subclass of {@link DataList} representing a many_many relation
 */
class ManyManyList extends RelationList {
	
	protected $joinTable;
	
	protected $localKey;
	
	protected $foreignKey, $foreignID;

	protected $extraFields;

	/**
	 * Create a new ManyManyList object.
	 * 
	 * A ManyManyList object represents a list of DataObject records that correspond to a many-many
	 * relationship.  In addition to, 
	 * 
	 * Generation of the appropriate record set is left up to the caller, using the normal
	 * {@link DataList} methods.  Addition arguments are used to support {@@link add()}
	 * and {@link remove()} methods.
	 * 
	 * @param string $dataClass The class of the DataObjects that this will list.
	 * @param string $joinTable The name of the table whose entries define the content of this many_many relation.
	 * @param string $localKey The key in the join table that maps to the dataClass' PK.
	 * @param string $foreignKey The key in the join table that maps to joined class' PK.
	 * @param string $extraFields A map of field => fieldtype of extra fields on the join table.
	 * 
	 * @example new ManyManyList('Group','Group_Members', 'GroupID', 'MemberID');
	 */
	public function __construct($dataClass, $joinTable, $localKey, $foreignKey, $extraFields = array()) {
		parent::__construct($dataClass);
		$this->joinTable = $joinTable;
		$this->localKey = $localKey;
		$this->foreignKey = $foreignKey;
		$this->extraFields = $extraFields;

		$baseClass = ClassInfo::baseDataClass($dataClass);

		// Join to the many-many join table
		$this->dataQuery->innerJoin($joinTable, "\"$joinTable\".\"$this->localKey\" = \"$baseClass\".\"ID\"");

		// Query the extra fields from the join table
		if($extraFields) $this->dataQuery->selectFromTable($joinTable, array_keys($extraFields));
	}

	/**
	 * Return a filter expression for the foreign ID.
	 */
	protected function foreignIDFilter() {
		// Apply relation filter
		if(is_array($this->foreignID)) {
			return "\"$this->joinTable\".\"$this->foreignKey\" IN ('" . 
				implode("', '", array_map('Convert::raw2sql', $this->foreignID)) . "')";
		} else if($this->foreignID !== null){
			return "\"$this->joinTable\".\"$this->foreignKey\" = '" . 
				Convert::raw2sql($this->foreignID) . "'";
		}
	}

	/**
	 * Add an item to this many_many relationship
	 * Does so by adding an entry to the joinTable.
	 * @param $extraFields A map of additional columns to insert into the joinTable
	 */
	public function add($item, $extraFields = null) {
		if(is_numeric($item)) $itemID = $item;
		else if($item instanceof $this->dataClass) $itemID = $item->ID;
		else throw new InvalidArgumentException("ManyManyList::add() expecting a $this->dataClass object, or ID value", E_USER_ERROR);
		
		// Validate foreignID
		if(!$this->foreignID) {
			throw new Exception("ManyManyList::add() can't be called until a foreign ID is set", E_USER_WARNING);
		}
		
		// Delete old entries, to prevent duplication
		$this->removeById($itemID);

		// Insert new entry/entries
		foreach((array)$this->foreignID as $foreignID) {
			$manipulation = array();
			$manipulation[$this->joinTable]['command'] = 'insert';

			if($extraFields) foreach($extraFields as $k => $v) {
				$manipulation[$this->joinTable]['fields'][$k] = "'" . Convert::raw2sql($v) . "'";
			}

			$manipulation[$this->joinTable]['fields'][$this->localKey] = $itemID;
			$manipulation[$this->joinTable]['fields'][$this->foreignKey] = $foreignID;

			DB::manipulate($manipulation);
		}
	}

	/**
	 * Remove the given item from this list.
	 * Note that for a ManyManyList, the item is never actually deleted, only the join table is affected
	 * @param $itemID The ID of the item to remove.
	 */
	public function remove($item) {
        if(!($item instanceof $this->dataClass)) throw new InvalidArgumentException("ManyManyList::remove() expecting a $this->dataClass object");
        
        return $this->removeByID($item->ID);
	}

	/**
	 * Remove the given item from this list.
	 * Note that for a ManyManyList, the item is never actually deleted, only the join table is affected
	 * @param $itemID The item it
	 */
	public function removeByID($itemID) {
	    if(!is_numeric($itemID)) throw new InvalidArgumentException("ManyManyList::removeById() expecting an ID");

		$query = new SQLQuery("*", array("\"$this->joinTable\""));
		$query->setDelete(true);
		
		if($filter = $this->foreignIDFilter()) {
			$query->setWhere($filter);
		} else {
			user_error("Can't call ManyManyList::remove() until a foreign ID is set", E_USER_WARNING);
		}
		
		$query->addWhere("\"$this->localKey\" = {$itemID}");
		$query->execute();
	}

    /**
     * Remove all items from this many-many join.  To remove a subset of items, filter it first.
     */
    public function removeAll() {
		$query = $this->dataQuery()->query();
		$query->setDelete(true);
		$query->setSelect(array('*'));
		$query->setFrom("\"$this->joinTable\"");
		$query->execute();
    }

	/**
	 * Find the extra field data for a single row of the relationship
	 * join table, given the known child ID.
	 *
	 * @todo Add tests for this / refactor it / something
	 *	
	 * @param string $componentName The name of the component
	 * @param int $childID The ID of the child for the relationship
	 * @return array Map of fieldName => fieldValue
	 */
	public function getExtraData($componentName, $childID) {
		$ownerObj = $this->ownerObj;
		$parentField = $this->ownerClass . 'ID';
		$childField = ($this->childClass == $this->ownerClass) ? 'ChildID' : ($this->childClass . 'ID');
		$result = array();

		if(!isset($componentName)) {
			user_error('ComponentSet::getExtraData() passed a NULL component name', E_USER_ERROR);
		}
		
		if(!is_numeric($childID)) {
			user_error('ComponentSet::getExtraData() passed a non-numeric child ID', E_USER_ERROR);
		}

		// @todo Optimize into a single query instead of one per extra field
		if($this->extraFields) {
			foreach($this->extraFields as $fieldName => $dbFieldSpec) {
				$query = DB::query("SELECT \"$fieldName\" FROM \"$this->tableName\" WHERE \"$parentField\" = {$this->ownerObj->ID} AND \"$childField\" = {$childID}");
				$value = $query->value();
				$result[$fieldName] = $value;
			}
		}
		
		return $result;
	}
}