returning variables from AJAX / php file - php

Question

I am using AJAX and trying to return variables that I got after querying the database in the modcomp.php file, I am then trying to input those values back into my main site to put into input boxes. Below is what I have tried but it is not working. Is this because I am getting variables in PHP and then bringing them back to use in JS / jQuery? Doing a few searches it looks like JSON might be the answer but looking at JSON I havent seen an example of how I could run code to query the database and then put that info in JSON format to pull back? My goal is to eventually pull back all 10 variables.
$.ajax({
method: "POST",
url: "modcomp.php",
data: {item: $(this).val()}
success: function(data) {
$('#itemnumber').val($itemnumber);
$('#cost').val($cost);
}
});
The modcomp.php file
<?php
if(array_key_exists("item", $_POST)) {
include("connection.php");
$query="SELECT * FROM components WHERE itemname = '".mysqli_real_escape_string($link,$_POST['item'])."' LIMIT 1";
if ($result=mysqli_query($link,$query)) {
$row=mysqli_fetch_array($result);
$id=$row[0];
$itemnumber=$row[1];
$itemname=$row[2];
$cost=$row[3];
$company=$row[4];
$contact=$row[5];
$address1=$row[6];
$address2=$row[7];
$phone=$row[8];
$part=$row[9];
//print_r ($id." ".$itemnumber." ".$itemname." ".$cost." ".$company." ".$contact." ".$address1." ".$address2." ".$phone." ".$part);
} else {
print_r("Issue with query");
}
}
?>

Answer 1

The easiest way to do that is just set your jquery.ajax to expect a json as return:
$.ajax({
method: "POST",
dataType: "JSON",
/** others attributes **/
After, convert your return to a json and print it (just it, nothing more) at php script:
//a better approach is return the column name (fetch_assoc)
echo json_encode($row);
Now, your return can be used as json:
success: function(data) {
data.column_name
}

Answer 2

json_encode is the answer
<?php
if(array_key_exists("item", $_POST)) {
include("connection.php");
$query="SELECT * FROM components WHERE itemname = '".mysqli_real_escape_string($link,$_POST['item'])."' LIMIT 1";
if ($result=mysqli_query($link,$query)) {
$row=mysqli_fetch_array($result);
$array = ();
$array['id']=$row[0];
$array['itemnumber']=$row[1];
$array['itemname']=$row[2];
.
.
$array['part']=$row[9];
$array['status'] = true;
echo json_encode($array);
} else {
echo json_encode(array(status => false , msg => "Issue with query");
}
}
Then in your js code use json as
$.ajax({
method: "POST",
url: "modcomp.php",
data: {item: $(this).val()}
success: function(data) {
data = JSON.parse(data); // to parse json string to object
if(data.status){
$('#itemnumber').val(data.itemnumber);
$('#cost').val(data.cost);
}
}
});

Answer 3

you should return your value from your php file as
<?php
if(array_key_exists("item", $_POST)) {
include("connection.php");
$query="SELECT * FROM components WHERE itemname = '".mysqli_real_escape_string($link,$_POST['item'])."' LIMIT 1";
if ($result=mysqli_query($link,$query)) {
$row=mysqli_fetch_array($result);
return json_encode($row,true);
} else {
return json_encode("Some error occured");
}
}
don't use print_r() function to return data from your php file
And set the datatype in ajax as JSON to parse the json data to be returned as
$.ajax({
method: "POST",
url: "modcomp.php",
datatype:'json',
data: {item: $(this).val()}
success: function(data) {
$('#itemnumber').val(data.itemnumber);
$('#cost').val(data.cost);
}
});
Now you are able to use your json data using the dot(.) operator like
$('#cost').val(data.cost);