Laravel Log Database Queries Based On Environment Variable

Jun 6, 2017 laravel php

This post is more than 18 months old. Since technology changes too rapidly, this content may be out of date (but that's not always the case). Please remember to verify any technical or programming information with the current release.

A nice feature of Laravel is the ability to add a listener to the DB object’s events (or SQL queries). I’ve seen some people add this, then comment it out when it’s done, then un-comment it if they need it again. I don’t like that - I don’t want commented code in my files (also that’s why we have version control).

Instead, let’s set an environment variable (using DotEnv), populate a Config option, and use that to invoke the listening.

First, add the following lines to your AppServiceProvider::boot() method:

if (Config::get('app.log_queries')) {
  DB::listen(function ($event) {
    Log::debug('app.log_queries log', [
      'sql' => $event->sql, 
      'bindings' => $event->bindings
    ]);
  });
}

If we have a configuration option named app.log_queries and it is truthy, we will define our database listener. Basically, it writes to the debug log every SQL statement and all of its bindings (or values).

Next, add the following line to your config/app.php file:

'log_queries' => env('LOG_QUERIES', false),

This set’s the value of the config option app.log_queries to whatever is in your environment, or false if it’s not set.

Finally, whenever you want to enable your local logging of database queries, you can add the following line to your local .env file:

LOG_QUERIES=true

If you don’t want to log them, then either remove the line or change the value to false - this makes it so that the only code you’re changing on the fly is your own copy of your environment (and not introducing changes, comments, etc - to the code base.)