source: Dev/trunk/classes/AnswerConnector.php @ 152

<?php
// Survey database interface class as intermediate for storing data from the site to the RDF database 
require_once 'rdfConstants.php';
// Include RAP Library to write RDF files
include(RDFAPI_INCLUDE_DIR . "RDFAPI.php");

/**
 * Description of AnswerConnector
 *
 * @author jkraaijeveld
 */
class AnswerConnector implements IConnector{
    protected $model;
        protected $fileName = 'data/answers/answers.rdf';
        protected $db;
    
    /**
     * Constructor for AnswerConnector
     */
    public function __construct() {
        //Ensure the required folder for this connector exists
        if (!is_dir('data/answers/'))
            mkdir('data/answers/');
    }
    
    /**
     * function load()
     * Loads the file into the standard MemModel.
     */
    public function load() {
        //Get the Memory Model from the ModelFactory
        $this->model = ModelFactory::getDefaultModel();
        
        //Ensure the required file exists before loading
        if(file_exists($this->fileName))
            $this->model->load($this->fileName);
    }
    
    /**
     * function save()
     * Saves the MemModel into the given file.
     */
    public function save() {
        $this->model->saveAs($this->fileName,'rdf'); 
    }
    
        /**
         * Function get()
         * Get the answers corresponding to the arguments
         * 'Question' argument is supposed to be the question ID
         * 'Values' has to be an array to make sure multiple answers can be selected.
         */
    public function get($arguments)
        {
                $this->load();
                $keys = array_keys($arguments);
                $uid = "?uid"; $question = "?question_code"; $value     = ""; 
                if(in_array("uid", $keys))
                        $uid = '\''.$arguments["uid"].'\'';
                if(in_array("question", $keys))
                        $question = '\''.$arguments["question"].'\'';
                if(in_array("values", $keys))
                {
                        foreach ($arguments["values"] as $val)
                        {
                                $value = $value . 'predicates:answered \'' . $val . '\' ';
                        }
                }
                //Create the querystring
                $querystring = '
                        PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
                        PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
                        SELECT DISTINCT ?uid, ?question_code
                        WHERE
                        {
                                _answer predicates:resource_type resources:answer;

                                predicates:uid ?uid ;
                                predicates:question_code ?question_code;

                                predicates:uid ' . $uid . '
                                predicates:question_code ' . $question . '      
                                ' . $value . '
                        }';

                //Query the model
                $results = $this->model->sparqlQuery($querystring);     
                //An answer can have multiple values, get all these values for the answer instances found.
                $answers = array();
                if(!empty($results))
                {
            $this->db = new DatabaseInterface();
                        foreach($results as $result)
                        {
                                $values = $this->getValues($result['?uid']->label);
                                $questionResult = $this->db->get("question", array("uid" => $result['?question_code']->label));
                                $answers[] = new Answer($result['?uid']->label, $questionResult[0], $values);
                        }
                }
                return $answers;

        }
        /**
         * Gets the values that belong to the answer
         * specified by the UID
         */
        private function getValues($uid)
        {
                $querystring = '
                        PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
                        PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
                        SELECT DISTINCT ?answered
                        WHERE 
                        {
                                _answer predicates:resource_type resources:answer ;
                                predicates:answered ?answered ;
                                predicates:uid \''. $uid . '\'
                }';
                $values = $this->model->sparqlQuery($querystring);
                $returnArray = array();
                if(!empty($values))
                {
                        foreach($values as $value)
                        {
                                $returnArray[] = $value['?answered']->label;
                        }
                }
                return $returnArray;
        } 

    /**
     * Saves the answer Object to the RDF file.
     * @param type $rToolObject
     */
    public function set($rToolObject)
    {
        $this->load();
        
        $resourceAnswer = new Resource(ANSWER.'/'.$rToolObject->uid);        
        //Remove the old value stored with the given id
        $this->model->subtract($this->model->find($resourceAnswer, null, null));
        
        //Save all the new values
        $resourceAnswerType = new Resource(ANSWER);
        $predicateRType = new Resource(RTYPE);
        $this->model->add(new Statement($resourceAnswer,$predicateRType,$resourceAnswerType));
        
                $answerId = new Literal($rToolObject->uid);
                $predicateId = new Resource(UID);
                $this->model->add(new Statement($resourceAnswer, $predicateId, $answerId));

                $questionId = new Literal($rToolObject->question->uid);
                $predicateQId = new Resource(QCODE);
                $this->model->add(new Statement($resourceAnswer, $predicateQId, $questionId));

                if(isset($rToolObject->values))
                {
                        foreach($rToolObject->values as $value)
                        {
                                $answerValue = new Literal($value);
                                $predicateAnswer = new Resource(ANSWERED);
                                $this->model->add(new Statement($resourceAnswer, $predicateAnswer, $answerValue));
                        }
                }
        $this->save();
    }
}

?>