// ------------------------------------------------------------------
// Throws Update Errors.
// In this case, the model is implemented using an MySQL database.
// If survey_id is absent from the database, exit with failure.
$matching_row = DB::queryFirstRow("SELECT * FROM credentials_stu WHERE survey_id = %i0", $survey_id);
if (is_null($matching_row)) {
die(bake_with_debug($return_value, 'Given survey_id does not yet exist in the model.'));
}
// Update survey_tag.
if ($change_survey_tag) {
// If new_survey_tag is already associated with a different survey id, exit with failure.
// Note that if previous duplicates exist, this will always fail.
$query = "SELECT * FROM credentials_stu WHERE survey_tag = %s AND survey_id <> %i";
$other_matching_survey_ids = DB::queryOneColumn('survey_id', $query, $new_survey_tag, $survey_id);
if (!empty($other_matching_survey_ids)) {
die(bake_with_debug($return_value, 'Duplicate survey_tag.'));
}
DB::query("UPDATE credentials_stu SET survey_tag = %s1 WHERE survey_id = %i0", $survey_id, $new_survey_tag);
}
// Update survey_start_date and survey_end_date.
if ($change_survey_time) {
// All integers are valid Unix timestamps.
$new_survey_start_datetime = (new DateTime())->setTimestamp($new_survey_start);
$new_survey_end_datetime = (new DateTime())->setTimestamp($new_survey_end);
var_dump($new_survey_start_datetime, $new_survey_end_datetime);
DB::query("UPDATE credentials_stu SET start_date = %t1, end_date = %t2 WHERE survey_id=%i0", $survey_id, $new_survey_start_datetime, $new_survey_end_datetime);
}
// ------------------------------------------------------------------
// Script exit with success.
// ------------------------------------------------------------------
$return_value->data->success = TRUE;
// Issues: Timezone is not considered yet; as of now, system manipulates pure UTC.
// ------------------------------------------------------------------
// Initialize return value to the failure message state.
$return_value = json_decode('{"debug": null, "data": {"survey_id": null, "success": false} }');
// Change debug member of return value, then get string rep of return value.
//TODO: move to a utilities file.
function bake_with_debug($mutable_return_value, $debug_string)
{
$mutable_return_value->debug = $debug_string;
return json_encode($mutable_return_value);
}
// ------------------------------------------------------------------
// Defines $server, $user, $pass, $dbname, and $port.
include 'connectionData.txt';
// Connect to SQL database.
$conn = mysqli_connect($server, $user, $pass, $dbname, $port) or die(bake_with_debug($return_value, 'Error connecting to MySQL server.'));
// ------------------------------------------------------------------
// Read _POST parameter.
$survey_tag = $_POST['survey_tag'];
// Fetch survey_id, and start and end times for survey with given survey_tag.
$query = "SELECT survey_id, start_date, end_date FROM credentials_stu WHERE survey_tag = '{$survey_tag}'";
// (The mysqli way of querying the database.)
if ($stmt = $conn->prepare($query)) {
$stmt->execute();
$stmt->bind_result($survey_id, $start_date, $end_date);
// Populate variables with query results, as bound above.
$stmt->fetch();
// Check if the SQL results are nonempty--i.e., user entered a valid survey_tag.
if (!is_null($survey_id)) {
// Credentials ok.
$return_value->data->survey_id = $survey_id;