unable to get POST data in php 'undefined index' error

Question

I am using plain javascript for Ajax request. when sending data by post method php throwing an error.

index.php

<html>

    <header>

        <script>
            function submit(){

                var userName = document.getElementById("username").value;
                var passWord = document.getElementById("password").value;


                var data = "username=" + userName + "&password=" + passWord;

                //send ajax request
                var xmlHttp = new XMLHttpRequest();
                xmlHttp.onreadystatechange = function()
                {
                    if(xmlHttp.readyState == 4 && xmlHttp.status == 200)
                    {
                        console.log(xmlHttp.responseText);
                    }
                }
                xmlHttp.open("post", "validateuser.php");
                xmlHttp.send(data);
            }
        </script>

    </header>

    <body>

            <label>User Name : </label>
            <input type="text" name="username" id="username"/>

            <label>Password : </label>
            <input type="text" name="password" id="password"/>

            <button onClick="submit()"> Login</button>

    </body>

</html>

validateuser.php

<?php

    $userName = $_POST["username"];
    $password = $_POST["password"];

echo $userName . $password;

What does your browser console say? Does it show that it successfully posted to validateuser.php? Does it show the data value as posted? — Sean
– Sean, Commented Feb 3, 2016 at 5:03
its out put php error. sayin  Notice: Undefined index: username in C:\wamp\www\redstone\formsapp\validateuser.php on line 3 and  Notice: Undefined index: password in C:\wamp\www\redstone\formsapp\validateuser.php on line 4 — Azad
– Azad, Commented Feb 3, 2016 at 5:05

score 5 · Accepted Answer · 2016-02-03 07:26:29Z

5

In Javascript ajax for post you need to add following line in your code:

xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

You can check documentation and example W3schools and developer mozilla

And for more reliable code just add following line to your php code

if(isset($_POST['username']) && isset($_POST['password'])){
     //your code
}

edited Feb 3, 2016 at 7:26

answered Feb 3, 2016 at 5:05

user5570620

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1 Comment

Sean Over a year ago

Using jquery's $.ajax() for so long, I forgot about this. Nice catch! +1 (although I would recommend linking to developer.mozilla.org/en-US/docs/AJAX/Getting_Started instead of w3schools)

Nijraj Gelani · Accepted Answer · 2016-02-03 05:08:23Z

1

You need to set the headers on your xmlHttp object. Add the following line before xmlHttp.send(data); line :

xmlHttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");

answered Feb 3, 2016 at 5:08

Nijraj Gelani

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