I remember I blogged about Laravel back in 2016 (time flies!), and reading them again, I am surprised that what I thought back in 2016 still applies today.

Today I am going to talk about some black magic I’ve encountered writing a test blog project. The bit that filling out the blog form and validating the data. Normally, when a form is posted to an URL, the controller validates the form data and throws validation exceptions if form is not validated, then the controller can redirect the browser back to the form along some error data to be displayed on the form. In Laravel, the redirecting back to the form is automatically done for you and somehow the view magically has the ‘errors’ variable in context.

Don’t assign different value types to the same variable

Let’s see what dynamic type in the simplest form in Python:

variable_a = True
if variable_a:
    variable_a = 'Result'

While this is perfectly legitimate, but it’s perfectly unacceptable, the rule of thumb is, you never assign a different type of value to a already defined variable.

variable_a = True
if variable_a:
    result = 'Result'

This way, when someone reads your code, one can safely assume result is always a ‘String’ type, seriously this will help a lot.

Don’t return different types of value in a function

Consider the following example, one would need to understand your condition in order to determine the type of result, also makes it difficult to consume this function.

def work():
    result = None
    variable_a = True
    if variable_a:
        result = 'Result'
    else
        result = 123

Define your class members at the top of the class

While this is perfectly legitimate:

class A(object):
    def work(self):
        self.member = 'abc'

But it’s difficult to work out what class members at a glance, please define them.

class A(object):
    def __init__(self):
        self.member = None

    def work(self):
        self.member = 'abc'

Now you know this class has a class member without reading the work function.

Exception is first class citizen

try:
    a = 1 / 0
except:
    print 'Caught'

Prints ‘Caught’

Let’s look at PHP:

try{ 
    $a = 1 / 0; 
}catch (Exception $e){ 
    print "Caught"; 
} 
I cannot believe by default this still gives me PHP Warning:  Division by zero

Better functions

Imagine you can write functions like this

def marry(man, woman):
    ...

marry('John', 'Julie')
marry(woman='Julie', man='John')

def party(*args):
    for person in args:
      print person

party('John')
party('John', 'Ben', ...)

def save(name, *kwargs):
    data = {'name': name}
    data.update(kwargs)
    write_to_db(data)

save('John')
save('John', gender='male', birthday='01/01/1970')

Short-lived vs Long-lived

Almost all PHP scripts are short-lived, including most frameworks, which means to serve a request, your PHP application will run from start to finish. However, Python can run as processes to serve requests, for example, A Django application runs as a process, so initiation code only runs once, serve a request, then wait for the next request to serve.

Imports Properly

Since 5.3, PHP introduced namespace, since they used .”dot” for concatenation, so they had to use the \”slash”, looks like this

namespace NZ\NET\LIN\Test

And use like this

use NZ\NET\LIN\Test

But it doesn’t actually import the Test class! Unless you use __autoload!

After setting up the quickstart project, I feel the project structure is quite different to Django. In Django a lot of code are organised in “app” domain, but it seems to me that multi-app is not something out-of-the-box in Laravel: https://laracasts.com/discuss/channels/general-discussion/laravel-5-multi-app-or-modular-applications

Instead, it seems the apps in Django is more similar to the “Service Providers” in Laravel.

ORM

While working on the quickstart project in Laravel, it seems to me that Eloquent doesn’t generate initial migratios based on model definition.

In Django, you define the model, then by running “makemigration” CLI command, it will generate initial migration files to create the database table for that model.

According to the quickstart project, it seems to be things work the other way around, you will have to manually create the migration files by running

php artisan make:migration create_tasks_table --create=tasks

And then create the model class by running

php artisan make:model Task

I did a google search “Laravel for Django developers” and got pretty much nothing useful, sure, who would have move back to PHP from Python? I think this only happens in New Zealand.

In the coming series, I will share my journey of learning Laravel, while comparing to Django, hopefully it will help out other Django developers like myself.

function get_range_dates($start, $end){
  $days = array();
  $start_tmp = explode("-",$start);
  $end_tmp = explode("-",$end);
  $start_time = mktime(1,1,1, $start_tmp[1], $start_tmp[2], $start_tmp[0]);
  $end_time = mktime(1,1,1, $end_tmp[1], $end_tmp[2], $end_tmp[0]);       
  while($start_time <= $end_time){           
    $days[] = date("Y-m-d", $start_time);
    $start_time += 86400;
  }
  return $days;
}

//calling the function
get_range_dates('2011-02-01', '2011-03-08');

Result:

Array ( [0] => 2011-02-01 [1] => 2011-02-02 [2] => 2011-02-03 [3] => 2011-02-04 [4] => 2011-02-05 [5] => 2011-02-06 [6] => 2011-02-07 [7] => 2011-02-08 [8] => 2011-02-09 [9] => 2011-02-10 [10] => 2011-02-11 [11] => 2011-02-12 [12] => 2011-02-13 [13] => 2011-02-14 [14] => 2011-02-15 [15] => 2011-02-16 [16] => 2011-02-17 [17] => 2011-02-18 [18] => 2011-02-19 [19] => 2011-02-20 [20] => 2011-02-21 [21] => 2011-02-22 [22] => 2011-02-23 [23] => 2011-02-24 [24] => 2011-02-25 [25] => 2011-02-26 [26] => 2011-02-27 [27] => 2011-02-28 [28] => 2011-03-01 [29] => 2011-03-02 [30] => 2011-03-03 [31] => 2011-03-04 [32] => 2011-03-05 [33] => 2011-03-06 [34] => 2011-03-07 [35] => 2011-03-08 )



Just a quick tutorial on drawing the server load bar chart in php:

serverload.php

function get_server_load($windows = 0)
{
    $os = strtolower(PHP_OS);
    if (strpos($os, "win") === false)
    {
        if (file_exists("/proc/loadavg"))
        {
            $load = file_get_contents("/proc/loadavg");
            $load = explode(' ', $load);
            return $load;
        }
        elseif (function_exists("shell_exec"))
        {
            $load = explode(' ', `uptime`);
            return $load;
        }
        else
        {
            return "";
        }
    }
}
list($one, $two, $three) = get_server_load();
//bar width
$width = 300;
//bar height
$height = 20;
$real_load = $one / 2;
$img_handle = imagecreate ($width, $height);
$box_color = imagecolorallocate ($img_handle, 255, 255, 255);
$bar_color = imagecolorallocate ($img_handle, 0, 195, 255);
$text_color = imagecolorallocate ($img_handle, 0, 0, 0);
$real_load = $real_load > 1 ? 1 : $real_load;
imagerectangle ( $img_handle , 0 , 0 , $width, $height, $box_color);
imagefilledrectangle ( $img_handle , 0 , 0 , (int)$width*$real_load, $height, $bar_color);
imagestring($img_handle, 5, $width/2-15, $height/2-7, ($real_load*100).'%', $text_color);
header ("Content-type: image/png");
imagepng ($img_handle);

html

<img src="serverload.php" style="border:1px solid black;"/>

User Home Page

Auto Include Index

Table Math

Modal Popup

ACL Made Easy

$b = array();
$a = array(array(1,2,3,4),array(5,6,7,8),array(9,0,1,2),array(3,4,5,6));

while(count($a)>0)
{
    $b[count($a[0])-1][] = array_shift($a[0]);
    if (count($a[0])==0)
    {
         array_shift($a);
    }
}

//use the Abraham's oAuth library
require_once 'twitteroauth/twitteroauth.php';

//replace the followng string
$key = 'key_string';
$secret = 'secret_string';
$oauth_token = 'auth_token_string';
$oauth_token_secret = 'auth_token_secret_string';

//the connection to twitter API
$connection = new TwitterOAuth($key, $secret, $oauth_token, $oauth_token_secret);

$params = array('count'=>200); // this is optional, gets 200 tweets
$tweets = $connection->get("statuses/replies", $params);

//see the object layout
print_r($tweets);