Return errors from PHP run via. AJAX?

Question

Is there a way to get PHP to return an AJAX error code if the PHP script fails somewhere? I was following a tutorial and typed this in to my PHP:

$return[\'error\         


        

Answer 1

For simple transfer of data from PHP to AJAX, Json encoding or key value pairs are not always necessary. It can be simply done using string handling.

A sample code explaining this functionality is below.

    $query = "SELECT email FROM login WHERE email = '". mysqli_real_escape_string($conn,$email) ."' AND password = '". mysqli_real_escape_string($conn,$pass) ."'" ;

    $result = mysqli_query($conn,$query);
    $row=mysqli_fetch_row($result);

    $row_cnt = mysqli_num_rows($result);
    $s_email = $row[0];

    if ($row_cnt == 1) {
        $response="success";
    } else {
    $response = "Invalid Credentials";
    }

    $conn->close();

    $_SESSION["email"]= $s_email;
    echo $response;

This code shows how a 'success' response is sent back to ajax calling the php code. Further in ajax the following could be done to retrieve the response.

    $.ajax({ type : 'POST',
          data : {email: $('#email').val(), password: $('#pass').val()},
          url  : 'login.php',              
          success: function (data) {
            if(data == 'success'){  //the value echoed from php can be stored in the data variable of ajax
                window.location.assign('upload.php');
            }
            else{
                alert(data);
            }
          },
          error: function ( xhr ) {
            alert("error");
        }
    });

The above concept can be extended to return MULTIPLE VALUES also. This method allows simple tranfer of data from PHP to AJAX in a string format.

We have to follow a simple step of echoing everything we need to send as a response from the php to ajax, seperated by a unique seperator.

    echo $response.#;
    echo $email.#;
    echo $password.#;
    echo "Hello".#;
    echo "World";

Then the variable data in ajax could be simply retrieved as in the above example and a simple function like,

    var res = data.split("#");

data, being the variable within ajax. The res array can then be used within js for whatever purpose we need.