Programming Archives

April 17, 2019April 30, 2019

How To Install Django on Ubuntu 18.04 LTS – Step by Step

Django is a popular Python framework for writing web applications. Web frameworks like Django provide a set of tools which helps the developer to write the application faster as the framework takes care of the internal structure, thus the developer needs to take care of the application development only. Django is free and open source software.

This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo’ to the commands to get root privileges. I will show you through the step by step installation Django on an Ubuntu 18.04 (Bionic Beaver) server.

Install Django on Ubuntu 18.04

Step 1. First, make sure that all your system packages are up-to-date

sudo apt-get update
sudo apt-get upgrade

Step 2. Installing Python 3 and venv.

Now you can install pip using the following command:

sudo apt install python3-venv

Next, Creating Virtual Environment:

mkdir my_django_app
cd my_django_app

Once inside the directory, run the following command to create your new virtual environment:

python3 -m venv venv

To start using this virtual environment, you need to activate it by running the activate script:

source venv/bin/activate

Step 4. Installing Djanggo with pip install

Once the pip is installed, run the following command to install Django:

sudo pip install django

To verify the Django version, run:

python -m django --version

Step 5. Create a sample Django project.

Now that the Django framework has been installed, you can to give it a test drive by creating a sample project:

cd ~
django-admin startproject mysite

The command above will create a directory myproject in your working directory ~, and store all necessary files within.

Run the commands below in sequence to get your application started. Follow the instructions on screen to provide the superuser’s credentials:

cd myidproject/
python3 manage.py migrate
python3 manage.py createsuperuser
python3 manage.py runserver

Step 6. Accessing Django.

Django will be available on HTTP port 8080 by default. Open your favorite browser and navigate to http://yourdomain.com:8000 or http://server-ip:8000/admin

Congratulation’s! You have successfully installed Django. Thanks for using this tutorial for installing Django web framework on Ubuntu 18.04 Bionic Beaver server. For additional help or useful information, we recommend you to check the official Django web site.

July 30, 2018April 2, 2019

How to fix Potential for Information Disclosure in CakePHP

The default application skeleton contained a beforeRender() method on the AppController that could potentially lead to unwanted information disclosure in your application. The unsafe default code was present between 3.1.0 and 3.5.0 of the application skeleton.

Risks

The default beforeRender hook would automatically serialize all view variables into JSON/XML if the _serialize view variable was not defined by the controller action. Controller methods that define the _serialize variable would behave correctly and only expose the named variables.

This behavior is triggered by the AppController and ErrorController loading RequestHandlerComponent, which configures the View class to be used based on the client’s Accept header. Then code in AppController::beforeRender() would enable all view variables to be serialized if no variables were explicitly listed.

The default controllers generated by bake set the _serialize view variable. This helps limit the impact, but could still lead to unwanted information exposure if entity classes are not correctly configured.

How to fix

You can fix the potential for information disclosure by modifying your application code. Unfortunately we cannot resolve this problem for you through a patch release of CakePHP or its appplication skeleton.

If you don’t have ErrorController in your src/Controller directory (CakePHP <= 3.3)

If you are using CakePHP 3.3.0 or greater and do not have an ErrorController in your application, you should download an ErrorController and put it into your src/Controller directory.

If you don’t use JSON/XML response based on client requests

Remove $this->loadComponent(‘RequestHandler’) from the initialize() method of your AppController and ErrorController.
Remove $this->set(‘_serialize’, true); from the beforeRender() of your AppController.

If you use JSON/XML response based on client requests

Remove $this->set(‘_serialize’, true); from the beforeRender() of your AppController.
Remove $this->set(‘_serialize’, [ (variable names) ]) from all controller actions, that should not return JSON/XML.
Add $this->set(‘_serialize’, [ (variable names) ]) explicitly to some actions of your controllers, which you want to return JSON/XML.

While we have no reports of information disclosure in the wild, this issue was found by Kurita Takashi and we felt this was important to disclose.

Read From Official CakePHP blog

July 10, 2017April 27, 2019

How to Learn Tutorial in CakePHP

CakePHP is an open-source framework for PHP. It is intended to make developing, deploying and maintaining applications much easier. CakePHP is based on an MVC-like architecture that is both powerful and easy to grasp. Models, Views, and Controllers guarantee a strict but natural separation of business logic from data and presentation layers.

Audience

This tutorial is meant for web developers and students who would like to learn how to develop websites using CakePHP. It will provide a good understanding of how to use this framework.

Prerequisites

Before you proceed with this tutorial, we assume that you have knowledge of HTML, Core PHP, and Advance PHP. We have used CakePHP version 3.2.7 in all the examples.

July 10, 2017April 2, 2019

How to view records from Database in CakePHP

To view records in CakePHP and To monitor records of database, we need to get hold of a table using the TableRegistry class. We can fetch the instance out of registry using get() method. The get() method will take the name of the database table as argument. Now, this new instance is used to find records from database using find() method. This method will return all records from the requested table.

Example

Make changes in the config/routes.php file as shown in the following code.

config/routes.php

<?php
   use Cake\Core\Plugin;
   use Cake\Routing\RouteBuilder;
   use Cake\Routing\Router;

   Router::defaultRouteClass('DashedRoute');
   Router::scope('/', function (RouteBuilder $routes) {
      $routes->connect('/users', ['controller' => 'Users', 'action' => 'index']);
      $routes->fallbacks('DashedRoute');
   });
   Plugin::routes();

Create a UsersController.php file at src/Controller/UsersController.php. Copy the following code in the controller file.

src/controller/UsersController.php

<?php
   namespace App\Controller;
   use App\Controller\AppController;
   use Cake\ORM\TableRegistry;
   use Cake\Datasource\ConnectionManager;

   class UsersController extends AppController{
      public function index(){
         $users = TableRegistry::get('users');
         $query = $users->find();
         $this->set('results',$query);
      }
   }
?>

Create a directory Users at src/Template, ignore if already created, and under that directory create a View file called index.ctp. Copy the following code in that file.

src/Template/Users/index.ctp

<a href = "add">Add User</a>
<table>
   <tr>
      <td>ID</td>
      <td>Username</td>
      <td>Password</td>
      <td>Edit</td>
      <td>Delete</td>
   </tr>

   <?php
      foreach ($results as $row):
         echo "<tr><td>".$row->id."</td>";
         echo "<td>".$row->username."</td>";
         echo "<td>".$row->password."</td>";
         echo "<td><a href = '".$this->Url->build
         (["controller" => "Users","action"=>"edit",$row->id])."'>Edit</a></td>";
         
         echo "<td><a href = '".$this->Url->build
         (["controller" => "Users","action"=> "delete",$row->id])."'>Delete</a></td></tr>";
      endforeach;
   ?>
</table>

Execute the above example by visiting the following URL.

http://localhost:85/CakePHP/users

Output

Upon execution, the above URL will give you the following output.

click here to read more cakePHP official website

How to fix Potential for Information Disclosure in CakePHP

July 10, 2017April 27, 2019

How to View Elements in CakePHP

Certain parts of the web pages are repeated on multiple web pages but at different locations. CakePHP can help us reuse these repeated parts. These reusable parts are called Elements − help box, extra menu etc. An element is basically a mini-view. We can also pass variables in elements.

Cake\View\View::element(string $elementPath, array $data, array $options =[])

There are three arguments to the above function −

The first argument is the name of the template file in the /src/Template/Element/ folder.
The second argument is the array of data to be made available to the rendered view.
The third argument is for the array of options. e.g. cache.

Out of the 3 arguments, the first one is compulsory while, the rest are optional.

Example

Create an element file at src/Template/Element directory called helloworld.ctp. Copy the following code in that file.

src/Template/Element/helloworld.ctp

<p>Hello World</p>

Create a folder Elems at src/Template and under that directory create a View file called index.ctp. Copy the following code in that file.

src/Template/Elems/index.ctp

Element Example: <?php echo $this→element('helloworld'); ?>

Make Changes in the config/routes.php file as shown in the following program.

config/routes.php

<?php
   use Cake\Core\Plugin;
   use Cake\Routing\RouteBuilder;
   use Cake\Routing\Router;

   Router::defaultRouteClass('DashedRoute');
   Router::scope('/', function (RouteBuilder $routes) {
      $routes->connect('/elementexample',['controller'=>'Elems','action'=>'index']);
      $routes->fallbacks('DashedRoute');
   });
   Plugin::routes();

Create an ElemsController.php file at src/Controller/ElemsController.php. Copy the following code in the controller file.

src/Controller/ElemsController.php

<?php
   namespace App\Controller;
   use App\Controller\AppController; 
   use Cake\ORM\TableRegistry;
   use Cake\Datasource\ConnectionManager;

   class ElemsController extends AppController{
      public function index(){
      }
   }
?>

Execute the above example by visiting the following URL.

http://localhost:85/CakePHP/element-example

Output

Upon execution, the above URL will give you the following output.

July 10, 2017April 27, 2019

How to View Events, Callbacks in CakePHP

There are several callbacks/events that we can use with View Events. These events are helpful to perform several tasks before something happens or after something happens. The following is a list of callbacks that can be used with CakePHP.

S.No	Event Function & Description
1	Helper::beforeRender(Event $event, $viewFile) The beforeRender method is called after the controller’s beforeRender method but before the controller renders view and layout. This receives the file being rendered as an argument.
2	Helper::beforeRenderFile(Event $event, $viewFile) This method is called before each view file is rendered. This includes elements, views, parent views and layouts.
3	Helper::afterRenderFile(Event $event, $viewFile, $content) This method is called after each View file is rendered. This includes elements, views,parent views and layouts. A callback can modify and return $content to change how the rendered content will be displayed in the browser.
4	Helper::afterRender(Event $event, $viewFile) This method is called after the view has been rendered but before the layout rendering has started.
5	Helper::beforeLayout(Event $event, $layoutFile) This method is called before the layout rendering starts. This receives the layout filename as an argument.
6	Helper::afterLayout(Event $event, $layoutFile) This method is called after the layout rendering is complete. This receives the layout filename as an argument.

July 10, 2017April 27, 2019

How to Working with Views in CakePHP

The letter “V” in the MVC is for Views. Views are responsible for sending output to user based on request. View Classes is a powerful way to speed up the development process.

View Templates

The View Templates file of CakePHP has default extension .ctp (CakePHP Template). These templates get data from controller and then render the output so that it can be displayed properly to the user. We can use variables, various control structures in template.

Template files are stored in src/Template/, in a directory named after the controller that uses the files, and named after the action it corresponds to. For example, the View file for the Products controller’s “view()” action, would normally be found in src/Template/Products/view.ctp.

In short, the name of the controller (ProductsController) is same as the name of the folder (Products) but without the word Controller and name of action/method (view()) of the controller (ProductsController) is same as the name of the View file(view.ctp).

View Variables

View variables are variables which get the value from controller. We can use as many variables in view templates as we want. We can use the set() method to pass values to variables in views. These set variables will be available in both the view and the layout your action renders. The following is the syntax of the set() method.

Syntax

Cake\View\View::set(string $var, mixed $value)

This method takes two arguments − the name of the variable and its value.

Example

Make Changes in the config/routes.php file as shown in the following program.

config/routes.php

<?php
   use Cake\Core\Plugin;
   use Cake\Routing\RouteBuilder;
   use Cake\Routing\Router;

   Router::defaultRouteClass('DashedRoute');
   Router::scope('/', function (RouteBuilder $routes) {
      $routes->connect('template',['controller'=>'Products','action'=>'view']);
      $routes->fallbacks('DashedRoute');
   });
   Plugin::routes();

Create a ProductsController.php file at src/Controller/ProductsController.php. Copy the following code in the controller file.

src/Controller/ProductsController.php

<?php
   namespace App\Controller;
   use App\Controller\AppController;
   
   class ProductsController extends AppController{
      public function view(){
         $this->set('Product_Name','XYZ');
      }
   }
?>

Create a directory Products at src/Template and under that folder create a View file called view.ctp. Copy the following code in that file.

src/Template/Products/view.ctp

Value of variable is: <?php echo $Product_Name; ?>

Execute the above example by visiting the following URL.

http://localhost:85/CakePHP/template

Output

The above URL will produce the following output.