source: Dev/trunk/rdfapi/sparql/SparqlEngineDb/ResultRenderer/JSON.php @ 12

<?php
require_once RDFAPI_INCLUDE_DIR . 'sparql/SparqlEngineDb/ResultRenderer.php';

/**
*   Sparql DB JSON Renderer. Roughly follows http://www.w3.org/2001/sw/DataAccess/json-sparql/;
*
*   @author Christoph Rieß
*   @license http://www.gnu.org/licenses/lgpl.html LGPL
*
*   @package sparql
*/
class SparqlEngineDb_ResultRenderer_JSON implements SparqlEngineDb_ResultRenderer
{

    /**
    *   Converts the database results into JSON Format
    *
    *   @param array $arRecordSets  Array of (possibly several) SQL query results.
    *   @param Query $query     SPARQL query object
    *   @param SparqlEngineDb $engine   Sparql Engine to query the database
    *   @return mixed   HTML code
    */
    public function convertFromDbResults($arRecordSets, Query $query, SparqlEngineDb $engine) {
        
        $this->query = $query;
        $this->sg    = $engine->getSqlGenerator();
        $strResultForm = $query->getResultForm();
        
        foreach ($this->getResultVars() as $var)
                $ResultVarsTemp[] = substr($var,1);
        
        switch ($strResultForm) {
            case 'select':
            case 'select distinct':
                $results = $this->createFromRecords($arRecordSets, $strResultForm);
                                $strCode = json_encode(array(
                                'head' => array('vars'=>$ResultVarsTemp),
                                'results'=>array('bindings'=>$results))
                                );
                                //$strCode = str_replace(',{',','.PHP_EOL.'{',$strCode);
                break;
                        case 'construct':
            case 'describe':
                throw new Exception(
                    'Construct and describe are not supported by the'
                    . ' JSON renderer'
                );

            case 'count':
            case 'ask':
                if (count($arRecordSets) > 1) {
                    throw new Exception(
                        'More than one result set for a '
                        . $strResultForm . ' query not supported by JSON Renderer'
                    );
                }

                $nCount = 0;
                $dbRecordSet = reset($arRecordSets);
                foreach ($dbRecordSet as $row) {
                    $nCount += intval($row['count']);
                    break;
                }

                if ($strResultForm == 'ask') {
                    $strcode = json_encode(array('boolean' => ($nCount > 0)));
                } else {
                    $strcode = json_encode(array('int' => $nCount ));
                }
                break;
            default:
                throw new Exception('Error');
        }
        
        return $strCode;
        

    }
    /**
     * Method to create from record with specific resultform (not used yet)
     *
     * @param array $arRecordSets  Array of (possibly several) SQL query results.
     * @param unknown_type $strResultForm
     * @return array ready for json conversion
     */
        protected function createFromRecords($arRecordSets, $strResultForm) {
                
                $arVarAssignments = $this->sg->arVarAssignments;
                $code = '';
                $arResultVars = $this ->getResultVars();
                $results = array();
                foreach ($arRecordSets[0] as $value) {
                        $node = array();
                        foreach ($arResultVars as $ResultVar) {
                                $nodeType = $value[$arVarAssignments[$ResultVar][0].'.'.$arVarAssignments[$ResultVar]['sql_is']];
                                if ($nodeType == 'r') {
                                        $node[substr($ResultVar,1)] = array('type'=> 'uri','value'=>$value[$arVarAssignments[$ResultVar][0].'.'.$arVarAssignments[$ResultVar]['sql_value']]);
                                        
                                }
                                
                                if ($value[$arVarAssignments[$ResultVar][0].'.'.$arVarAssignments[$ResultVar]['sql_is']] == 'l') {
                                        $literalType = $value[$arVarAssignments[$ResultVar][0] . 
                                                '.' . $arVarAssignments[$ResultVar]['sql_type']];
                                        $literalLang = $value[$arVarAssignments[$ResultVar][0] . 
                                                '.' . $arVarAssignments[$ResultVar]['sql_lang']];
                                        $literalValue = $value[$arVarAssignments[$ResultVar][0] . 
                                                '.' . $arVarAssignments[$ResultVar]['sql_value']];
                                        $node[substr($ResultVar,1)] = $this->getLiteral($literalValue,$literalLang,$literalType);
                                }
                                
                                if ($nodeType === 'b') {
                                        $literalValue = $value[$arVarAssignments[$ResultVar][0].'.'.$arVarAssignments[$ResultVar]['sql_value']];
                                        $node[substr($ResultVar,1)] = array ('type'=>'bnode' ,'value'=>$value[$arVarAssignments[$ResultVar][0].'.'.$arVarAssignments[$ResultVar]['sql_value']]);
                                }
                        }
                        $results[]=$node;
                        
                        
                }
                return $results;

        }
        
        /**
         * COnverting Literals to array ready for json
         *
         * @param unknown_type $value
         * @param unknown_type $lang
         * @param unknown_type $type
         * @return unknown
         */
        private function getLiteral($value, $lang , $type) {
                
                $ret = array();
                
                $type = 'literal';
                
                if ($value != 'literal') {
                        $ret['value'] = $value;
                }
                
                if ($lang != '') {
                        $ret['lang'] = $lang;
                }
                
                if ($type != '') {
                        $ret['type'] = $type; 
                }
                
                return $ret;
        }
        
        /**
         * Giving array of used Vars also resolves the all-quantifier *
         *
         * @return array of vars as strings
         */
        protected function getResultVars() {
                $arResultVars = $this->query->getResultVars();
                if (in_array('*', $arResultVars)) {
                        $arResultVars   = array_keys($this->sg->arVarAssignments);
                } else {
                        $arResultVars = array();
                        foreach ($this->query->getResultVars() as $Var) {
                                $arResultVars[] = (string) $Var;
                        }
                }
                
                return $arResultVars;
        }

}

?>