common/models/resources/ModelHierarchy.php
public static function findChild( $parentId, $parentType, $childId ) {

		return self::find()->where( 'parentId=:pid AND parentType=:type AND childId=:cid', [ ':pid' => $parentId, ':type' => $parentType, ':cid' => $childId ] )->one();
	}
public static function findChild( $parentId, $parentType, $childId ) {

		return self::find()->where( 'parentId=:pid AND parentType=:type AND childId=:cid', [ ':pid' => $parentId, ':type' => $parentType, ':cid' => $childId ] )->one();
	}
public static function findChild ( $ parentId , $ parentType , $ childId ) { return self :: find ( ) -> where ( 'parentId=:pid AND parentType=:type AND childId=:cid' , [ ':pid' => $ parentId , ':type' => $ parentType , ':cid' => $ childId ] ) -> one ( ) ; }
Find and return the child using parent id, parent type and child id.

@param integer $parentId
@param string $parentType
@param integer $childId
@return ModelHierarchy
Find and return the child using parent id parent type and child id .