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Forked from therealklanni/JSONP_Example.php
Created July 15, 2017 20:55
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Simple public Web API in PHP using JSONP
<?php
/* JSONP_Example.php
* Author: Kevin Lanni
* Description: Demonstrates how to create a simple public Web API using JSONP responses
* This is useful for opening Web APIs for public use without the need for proxying or other SOP work-arounds.
* This example does not demonstrate API keys or any other method of authentication.
*/
// Supply a header to set the proper expectation for the client browser
header('Content-Type: application/json');
// A simple error handler, so we can output the error to the requesting script instead of failing silently
function errHandler($errno, $errstr) {
switch ($errno) {
// You can specify specific response data depending on error type, but for this example we'll only set a default
default:
$result = Array(
"success" => false,
"error" => $errstr,
"params" => $_GET
);
if (isset($_GET["callback"])) {
echo $_GET["callback"] .'('. json_encode($result) .');';
} else {
echo json_encode($result);
}
exit;
break;
}
}
// Set our errHandler function above to be the default error handler for PHP
set_error_handler("errHandler");
//
// Here you would put your PHP code that handles the API requests and builds responses.
//
// What I like to do is set a variable such as "$result" to an assoc array for my JSON data, like so:
$result = array(
"success" => true,
"message" => "You have successfully implemented a simple Web API using JSONP!"
);
// Then I would convert it to JSON using json_encode at the end of the script, when I'm ready to generate the output.
// For error handling, I use trigger_error, which is as simple as:
// if ($some_condition == "unmet") {
// trigger_error("Some condition was not met!", E_USER_ERROR); // Where E_USER_ERROR can be any valid PHP error constant (http://www.php.net/manual/en/errorfunc.constants.php)
// }
// The script would stop executing as soon as the first error is detected, because we exit the script in the error handler. This helps prevent lockups.
// Of course, you may want to handle warnings less strictly and do something else for your warnings. See error handler.
// Uncomment this if-statement to see an error thrown for "Undefined variable: some_condition". Uncomment just the trigger_error statement to see a custom error message.
// Once we're done executing all the necessary code to generate our data, let's convert it to JSON and print it out
if (isset($_GET["callback"])) {
echo $_GET["callback"] .'('. json_encode($result) .');';
} else {
// Just in case we're not making cross domain requests, we can forego the JSONP and just expect regular JSON
echo json_encode($result);
}
?>
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