function wl_ajax_sparql()
{
header('Access-Control-Allow-Origin: *');
// Get the query slug.
$slug = $_GET['slug'];
// Get the output format: csv or geojson.
$format = empty($_GET['format']) ? 'csv' : $_GET['format'];
// TODO: define an output format.
$output = 'csv';
$accept = 'text/csv';
// Get the query.
$query = wl_sparql_replace_params(wl_sparql_get_query_by_slug($slug), $_GET);
$dataset = wl_sparql_get_query_dataset_by_slug($slug);
// Print out the query if the debug flag is set.
if (isset($_GET['_debug']) && 1 == $_GET['_debug']) {
wp_die($query);
}
if (empty($query)) {
wp_die("Cannot find a SPARQL query [ slug :: {$slug} ]");
}
$url = wl_configuration_get_query_select_url($output, $dataset) . urlencode($query);
// Prepare the request.
$args = array('method' => 'GET', 'headers' => array('Accept' => $accept));
// Send the request. Raise actions before and after the request is being sent.
do_action('wl_sparql_pre_request', $url, $args, $query);
// Send the request via caching if the module is available.
$response = function_exists('wl_caching_remote_request') ? wl_caching_remote_request($url, $args) : wp_remote_post($url, $args);
do_action('wl_sparql_post_request', $url, $args, $query, $response);
// If an error has been raised, return the error.
if (is_wp_error($response) || 200 !== (int) $response['response']['code']) {
echo "wl_execute_sparql_query ================================\n";
if (is_wp_error($response)) {
var_dump($response);
} else {
echo " request : \n";
var_dump($args);
echo " response: \n";
var_dump($response);
echo " response body: \n";
echo $response['body'];
}
echo "=======================================================\n";
return false;
}
// Output the data according to the chosen format.
switch ($format) {
case 'geojson':
wl_csv_to_geojson($response['body']);
break;
case 'json':
wl_csv_to_json($response['body']);
break;
default:
echo $response['body'];
}
wp_die();
}
/**
* Execute the provided query against the SPARQL SELECT Redlink end-point and return the response.
*
* @param string $query A SPARQL query.
* @param string $accept The mime type for the response format (default = 'text/csv').
*
* @return WP_Response|WP_Error A WP_Response instance in successful otherwise a WP_Error.
*/
function rl_sparql_select($query)
{
// Prepare the SPARQL statement by prepending the default namespaces.
$sparql = rl_sparql_prefixes() . "\n" . $query;
// Get the SPARQL SELECT URL.
$url = wl_configuration_get_query_select_url('csv') . urlencode($sparql);
// Prepare the request.
$args = unserialize(WL_REDLINK_API_HTTP_OPTIONS);
// Send the request.
wl_write_log("SPARQL Select [ sparql :: {$sparql} ][ url :: {$url} ][ args :: " . var_export($args, true) . " ]");
return wp_remote_get($url, $args);
}
