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Inside this article we will see the concept to define global constant in codeigniter 4. Global constant simply means variables which we can access anywhere inside application at any point. Value for constants is fixed for lifetime. We can’t alter values for those.
List of all available global constants in CodeIgniter 4, Click here for article.
Here we will discuss to create global constant step by step and how to use in codeigniter 4 application.
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Let’s get started.
CodeIgniter 4 Installation
To create a CodeIgniter 4 setup run this given command into your shell or terminal. Please make sure composer should be installed.
$ composer create-project codeigniter4/appstarter codeigniter-4
Assuming you have successfully installed application into your local system.
When we install CodeIgniter 4, we will have env file at root. To use the environment variables means using variables at global scope we need to do env to .env
Either we can do via renaming file as simple as that. Also we can do by terminal command.
Open project in terminal
$ cp env .env
Above command will create a copy of env file to .env file.
Now we are ready to use environment variables.
Enable Development Mode
CodeIgniter starts up in production mode by default. You need to make it in development mode to see any error if you are working with application.
Open .env file from root.
# CI_ENVIRONMENT = production // Do it to CI_ENVIRONMENT = development
Now application is in development mode.
What is a Global Constant?
Global constants are also termed as core constants of application. It simply means theses –
- Variables which can accessed through out application means globally available to use.
- Values of constants can’t be altered upto it’s lifetime.
- We can define constant using PHP function define()
Define Global Constant in Application
Global constants can be define in two ways inside Codeigniter 4 application. These are the following ways –
- By using .env file
- By using Constants.php file
Global Constant using .env (environment) file
Open .env file from application root. To define global constants, simply define like this
... MY_CONSTANT="This is a global constant defined in .env file" ...
How To Use?
To call inside application files, use getenv() function of codeigniter 4.
<?php echo getenv('MY_CONSTANT') ?> OR <?= getenv('MY_CONSTANT') ?> OR <?= env('MY_CONSTANT') ?>
Global Constant Using Constants.php File
Open Constants.php file from /app/Config folder. Here, to define global constants we use php function define()
Add this line at footer of file –
... defined('MY_CONSTANT') || define('MY_CONSTANT', 'This is a global constant defined in Constants.php file'); ...
defined(‘MY_CONSTANT’) It is checking first that constant is already exists or not. If not then using define() it is creating.
How To Use?
To call inside application files, use like this.
<?php echo MY_CONSTANT; ?> OR <?= MY_CONSTANT ?>
We hope this article helped you to learn about How To Define Global Constant in CodeIgniter 4 Tutorial in a very detailed way.
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