Why are echo messages showing in my JSON response and how to I prevent them from being echoed out to the browser console? [closed]

Question

I have the following PHP code:

<?php
header("Access-Control-Allow-Origin: *");

include_once('../includes/mysql_connect.php');
include_once('../db/tables/search.php');

// SAVE TO DB
$search = new search($mysql);
//$search->drop();
//$search->create();
$search->save(array("shop" => "test store", "searchterm" => $_POST['search']));


// LOG TO FILE
$file = fopen('search-data.txt', 'a+');
$result = fwrite($file, "\nsearch query data: " . print_r($_POST['search'], true) );    

// SEND RESPONSE
$response = array('response' => 'received', 'data' => $_POST['search'] );
echo json_encode($response);

When I look on the browser console I see this:

<br>INSERT QUERY SUCCESSFUL: insert_id=69{"response":"received","data":"product"}

The "INSERT QUERY SUCCESSFUL" is coming from my DB class which does the INSERT and echos out various messages. How can I show only the JSON response in the last two lines of code and not these echoed out messages? I want to keep these messages in my DB class for the moment. I wouldn't have expected anything else other than the data in the response array to be displayed in the console.

Answer 1

Don't use echo as a logging mechanism. It's specifically for sending content to the browser. If you want to log things, you need to log them to a file or via error_log, not via echo.

I wouldn't have expected anything else other than the data in the response array to be displayed in the console.

This is completely incorrect, and there is absolutely no reason to expect this. $response is just a random variable, no different from any other variable. PHP doesn't know that you wanted one invocation of echo to behave differently than your other ones, just because of the name of the variable you passed to it. Everything you echo goes to the browser, by design. You could try to work around this with output buffers, but don't. Don't use echo for logging, this is fundamentally at odds with how PHP works.