从GET切换到POST

Question

I have the following Ajax request:

// JavaScript
function myFunc(pid) {
    $.ajax({
        type : "GET",
        url : "testback.php",
        contentType : "application/json; charset=utf-8",
        dataType : "json",
        data : {
            q : "testrequest",
            pid : pid
        },
        success : function(data) {
            console.log(data)
        },
        error : function(jqXHR, status, error) {
            console.log(status, error);
        }
    });
}

// PHP
require_once ("dbconnect.php");
if (isset ( $_GET ['q'] )) {
    if ($_GET ['q'] == "testrequest") {
        $pid = $_GET ['pid'];

        $query = "SELECT * FROM `tab1` WHERE `pid` = " . $pid;

        $json = array ();
        if ($result = $link->query ( $query )) {
            while ( $row = $result->fetch_assoc () ) {
                array_push ( $json, $row );
            }
        }

        header ( "Content-type: application/json; charset=utf-8" );
        die ( json_encode ( $json ) );
        exit ();
    }
    die ();
}

It sends a request to my MySQL database and returns the expected output.

However, I now want to switch to POST, rather than GET.
When I just swap GET with POST:

// JavaScript
function myFunc(pid) {
    $.ajax({
        type : "POST", // POST
        url : "testback.php",
        contentType : "application/json; charset=utf-8",
        dataType : "json",
        data : {
            q : "testrequest",
            pid : pid
        },
        success : function(data) {
            console.log(data)
        },
        error : function(jqXHR, status, error) {
            console.log(status, error);
        }
    });
}

// PHP
require_once ("dbconnect.php");
if (isset ( $_POST ['q'] )) { // POST
    if ($_POST ['q'] == "testrequest") { // POST
        $pid = $_POST ['pid']; // POST

        $query = "SELECT * FROM `tab1` WHERE `pid` = " . $pid;

        $json = array ();
        if ($result = $link->query ( $query )) {
            while ( $row = $result->fetch_assoc () ) {
                array_push ( $json, $row );
            }
        }

        header ( "Content-type: application/json; charset=utf-8" );
        die ( json_encode ( $json ) );
        exit ();
    }
    die ();
}

I get the following error in the console:

parsererror SyntaxError: Unexpected end of JSON input

The request payload is still q=testrequest&pid=1.

What else do I need to change, in order to switch from GET to POST?

Answer 1

In your Ajax function you need to omit the content type as it is already defined in the Ajax Call. Delete the line "contentType : "application/json; charset=utf-8" shown below:

$.ajax({
    type : "GET", // Or POST
    url : "testback.php",
    contentType : "application/json; charset=utf-8", // REMOVE THIS LINE!!
    dataType : "json",
    data : {
        q   : "testrequest",
        pid : pid
    },
    success : function(data) {
        console.log(data)
    },
    error : function(jqXHR, status, error) {
        console.log(status, error);
    }
});

It should work just fine after that! Cheers!