can not Send data to php file using ajax

Question

I have this php file graph.php

$host = $_POST['hostname'];
echo $type=$_POST['type_char'];
include('rrdtools.inc.php');
include('graphs/'.$type.'.inc.php');

and I trying to send data to this file using this ajax code

var type_char='fortigate_cpu';//$('#graph').val();
var hostname='10.10.0.144';//$(this).attr('id');
//$('#device_host').val(id);

$.ajax({
    type: 'POST',
    url: 'SNMP/graph.php',
    data: { hostname:hostname,type_char:type_char },
    success: function(data) {
        alert(data);
        // show the response
        $("#grph").attr("src", 'SNMP/graph.php');
        console.log(data);
    }
});

the result when I send data to that file is

fortigate_cpu as a value of type_char variable when I opened error.log file in apache logs I have this message

include(): Failed opening 'graphs/.inc.php' for inclusion (include_path='.:/usr/share/php')

as you see the value of fortigate not included in include function even if the char_type variable is send by ajax and printed in page include file must be as this

include( 'graphs/fortigate_cpu.inc.php')  

why type not included in the include session even if the variable is received from ajax

Answer 1

As was mentioned by other users in the comments, maybe your issue is that you are setting type to a different value after including rrdtools.inc.php .

Try randomizing ( changing the name), of the type variable:

$host = $_POST['hostname'];
echo $type123456=$_POST['type_char'];
include('rrdtools.inc.php');
include('graphs/'.$type123456.'.inc.php');

It's the only thing I can think of, since both I (and others) have tested your code. (both front-end and back-end).

PS: Include using post param is a bad practice.