Fatal error: Uncaught Error: Call to undefined function get_option()

Question

I want to solve this problem as I am sending ajax request from on plugin page to another file verifyapi.php but it gives me error like below.

Fatal error: Uncaught Error: Call to undefined function get_option() in verifyapi.php

But when adding below line

require_once('../../../../../wp-config.php');

on top of verifyapi.php it works fine but I don't want it as WordPress don't allow you to add any WordPress core file in your function so is there any other way to do it.

Here is the js code of admin-ui.php page which sends data to verifyapi.php and then get a response back from it.

function savedata()
{
  var keyflag=document.getElementById("key_box_flag").value;
  if(keyflag=1)
  {
    var key=document.getElementById("key_box").value;
  jQuery.ajax({
   url:"<?php echo plugins_url( '/', __FILE__ ); ?>verifyapi.php",
   type:"POST",
   async:true,
   data:{"key":key,
       "save":1 },
   success: function(data)
   {
    location.reload();
   }

  });

  }
  else {

  }
}

Answer 1

Instead of doing this, simply write your own function inside the verifyapi.php and then include it in your plugin's main file, by using this:

require_once('verifyapi.php');

This way, you have access to WordPress's function inside your verifyapi.php file.

Now, inside your verifyapi.php file, create an Ajax handler (however I would recommend using a REST endpoint) :

add_action('wp_ajax_your_', 'handler_function');
add_action('wp_ajax_nopriv_your_handler_name', 'handler_function');
function photogram_ajax_handler() {
    // Your verification here
}

So far so good. One last step is to change the URL to admin-ajax.php. To do so, use this:

   ...
   url:"<?php echo site_url('/wp-admin/admin-ajax.php'); ?>",
   ...

All set.