Ajax Error Reporting In PHP Not Using JSON - php

Question

So I'm a bit confused.
I need to add an error handler to my AJAX depending on the result from PHP.
I was wondering if there was a way for me to add a variable like $success = error or $success = success in my PHP to trigger the AJAX functions.
I did some reading but everything I read involves JSON.
Here is my PHP with the $success variables where they should be, but I'm not sure where to start with the AJAX.
I'm not asking for a code to be written for me, but just some guidance.
if(isset($_POST['submit'])) {
require($_SERVER['DOCUMENT_ROOT']."/settings/functions.php");
$conn = getConnected("oversizeBoard");
if(empty($_POST['first_name'])) {
$success = "error";
echo "First Name Is Required.";
exit();
}
else {
$first_name = mysqli_real_escape_string($conn, $_POST['first_name']);
}
if(empty($_POST['last_name'])) {
$success = "error";
echo "Last Name Is Required.";
exit();
}
else {
$last_name = mysqli_real_escape_string($conn, $_POST['last_name']);
}
if(empty($_POST['email'])) {
$success = "error";
echo "Email Is Required.";
exit();
}
else {
$email = mysqli_real_escape_string($conn, $_POST['email']);
}
if(!empty($_POST['first_name']) && !empty($_POST['last_name']) && !empty($_POST['email'])) {
$checkEmail = mysqli_query($conn, "SELECT * FROM subscriptions WHERE email='$email'");
if(mysqli_num_rows($checkEmail) > 0){
$success = "error";
echo "You Are Already Subscribed!";
}
else {
if (!mysqli_query($conn,$checkEmail)) {
$subscribeQuery = "INSERT INTO subscriptions (first_name, last_name, email) VALUES ('$first_name', '$last_name', '$email')";
if (mysqli_query($conn, $subscribeQuery)) {
$success = "success";
echo "You Have Successfully Subscribed!";
}
else {
echo "Error: ".mysqli_error($conn);
}
}
}
mysqli_close($conn);
}
}
else {
echo "You Are not Authorized To View This Page.";
}
And the AJAX:
function submitForm() {
$.ajax({type:'POST', url: 'http://example.com/form/postSubscription.php', data:$('#subscription_form').serialize(),
error: function(response) { // if php variable is $success = "error"
notif({
msg: response,
type: "error",
position: "center"
});
},
success: function(response) { // if php variable is $success = "success"
notif({
msg: response,
type: "success",
position: "center"
});
}});
return false;
}
Do I need to use JSON to accomplish this or is there another way?

Answer 1

Rather than using echo "You Have Successfully Subscribed!"; etc, you probably want to create an output object/array up front, and then populate it with the data you want. Like this:
$data['text']= "You Have Successfully Subscribed!";
$data['success'] = "success";
Then you finish up with something like this:
header('Content-Type: application/json');
echo json_encode($data);
make sure you don't do any echo statements prior to the header or you'll get an error. Also, you don't want to do any echo statements other than the json_encode, or your json probably won't be parsed correctly.
On the client side, in your $.ajax, your success would work something like this:
$.ajax({ ...
success: function(response){
if(response.success=="success") {
$('#output').text(response.text);
}
}
});