source: Dev/branches/jos-branch/classes/models/AnswerSet.php @ 215

<?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");

/**
 * AnswerSet is a collection of answers corresponding to a Session
 *
 */
class AnswerSet extends ResearchToolObject{
        public static $filename = 'data/answers/answersets.rdf';

        public $survey;
        public $respondent;
        public $answers;

        /**
         * Constructor for an AnswerSet object
         * @param type $uid
         * @param type $survey
         * @param type $respondent
         * @param type $answers
         */
        public function __construct($uid=null, $survey=null, $respondent=null, $answers=null)
        {
                if(!isset($uid))
                {
                        $uid = md5(uniqid(rand(), true));
                }
                $this->uid = $uid;
                $this->survey = $survey;
                $this->respondent = $respondent;
                $this->answers = $answers;
        }

        /**
         * function evaluate()
         * evaluates the references of survey, respondent and answers.
         */
        public function evaluate()
        {
                if(is_string($this->survey))
                {
                        $result = Survey::get(array("uid" => $this->survey));
                        if(!isset($result[0]))
                                return false;
                        $this->survey = $result[0];
                }
                if(is_string($this->respondent))
                {
                        $result = Respondent::get(array("uid" => $this->respondent));
                        if(!isset($result[0]))
                                return false;
                        $this->respondent = $result[0];
                }
                if(!empty($this->answers) && is_string($this->answers[0]))
                {
                        $newanswers = array();
                        foreach($this->answers as $answer)
                        {
                                $result = Answer::get(array("uid" => $answer));
                                if(!isset($result[0]))
                                        return false;
                                $newanswers[] = $result[0];
                        }
                        $this->answers = $newanswers;
                }
                return true;
        }


        /**
         * function save()
         * Saves the current object into the database.
         */
        public function save()
        {
                //If evaluation fails, some references are incorrect.
                //We shouldn't save in this case. Instead - let the user know. This function returns false if the evaluation has failed.
                //TODO: Decide how to fix invalid references graciously.
                if(!$this->evaluate()) 
                        return false;
                //Ensure the required folder exists.
                if(!is_dir('data/answers/'))
                        mkdir('data/answers/');

                $model = ResearchToolObject::load(AnswerSet::$filename);


                $resourceAnswerSet = new Resource(ANSWERSET . '/' . $this->uid);
                //Remove the old value stored with the given id
                $model->subtract($model->find($resourceAnswerSet, null, null));

                //Set the new values
                $resourceAnswerSetType = new Resource(ANSWERSET);
                $predicateRType = new Resource(RTYPE);
                $model->add(new Statement($resourceAnswerSet, $predicateRType, $resourceAnswerSetType));

                $answerSetId = new Literal($this->uid);
                $predicateId = new Resource(UID);
                $model->add(new Statement($resourceAnswerSet, $predicateId, $answerSetId));

                $surveyId = new Literal($this->survey->uid);
                $predicateSurvey = new Resource(FOR_SURVEY);
                $model->add(new Statement($resourceAnswerSet, $predicateSurvey, $surveyId));

                $respondentId = new Literal($this->respondent->uid);
                $predicateRespondent = new Resource(BY_RESPONDENT);
                $model->add(new Statement($resourceAnswerSet, $predicateRespondent, $respondentId));
                
                if(isset($this->answers))
                {
                        foreach($this->answers as $answer)
                        {
                                $answerId = new Literal($answer->uid);
                                $predicateAnswer = new Resource(GIVEN_ANSWER);
                                $model->add(new Statement($resourceAnswerSet, $predicateAnswer, $answerId));
                        }
                }
                $model->saveAs(AnswerSet::$filename, 'rdf');
                return true;
        }

        /**
         * function get()
         * @param type $arguments : An array having one ore more of the following elements:
         * 'uid', 'survey', 'respondent', 'answers'.
         */
        public static function get($arguments)
        {
                $model = ResearchToolObject::load(AnswerSet::$filename);

                //Build the query string
                $querystring = '
                        PREFIX predicates: <' . SURVEYTOOL_PREDICATES_NAMESPACE . '>
                        PREFIX resources: <' . SURVEYTOOL_RESOURCES_NAMESPACE . '>
                        SELECT DISTINCT ?uid, ?for_survey, ?by_respondent
                        WHERE
                        {
                                _answerset      predicates:resource_type        resources:answerset ;
                                predicates:uid ?uid ;
                                predicates:for_survey ?for_survey ;
                                predicates:by_respondent ?by_respondent ;
                                ' . ResearchToolObject::createArguments($arguments) . '
                        }';
                //Query the model
                $results = $model->sparqlQuery($querystring);
                $answerSets = array();
                if(!empty($results))
                {
                        foreach($results as $result)
                        {
                                $survey = $result['?for_survey']->label;
                                $respondent = $result['?by_respondent']->label;
                                $answers =      AnswerSet::getAnswers($model, $result['?uid']->label);
                                $answerSets[] = new AnswerSet($result['?uid']->label, $survey, $respondent, $answers);
                        }
                }
                return $answerSets;
        }

        /**
         * function getAnswers()
         * @param type $uid : the uid for which the answers should be retrieved.
         */
        private static function getAnswers($model, $uid)
        {
                $result = $model->findRegex("[(".$uid.")]", "[(given_answer)]", null);
                $iterator = $result->getStatementIterator();
                $answers = array();
                while($iterator->hasNext())
                {
                        $element = $iterator->next();
                        $answers[] = $element->getLabelObject();
                }
                return $answers;
        }
}