# Extensions
# Why?
In the real world, everybody needs more than saving and listing records. Everybody needs more complicated logic in their code. AdonisX provides you a basic structure of an API. It provides you basic CRUD actions with where dynamic query options. But when you need custom logic, you will not be alone. AdonisX provides you some points to extend your HTTP requests and manipulate them.
There are two different ways to add your business logic;
- Events
- Actions
You may use Events and Actions to add your business logic.
# Events
Events are AdonisJS' features and you can read its documentation in here. It is very simple to use. First, you define an event to listen;
// start/event.js
Event.on('new::user', 'User.registered')
Then you create a file which is called User.js under the app/Listeners directory like this;
// app/Listeners/User.js
const User = exports = module.exports = {}
User.register = async (params) => {
// Your business logic.
}
After these definitions, whenever you fire the event, your register method will be triggered.
Event.fire('new::user')
AdonisX uses this structure. It fires constant events when an event has appeared. For example, if you want to handle the user's request before pagination, you should define an event like this;
Event.on('onBeforePaginateUser', 'User.onBeforePaginate')
AdonisX automatically fires onBeforePaginate event before the pagination in MainController. You can use the following list to understand which events will be triggered by AdonisX;
| EventName{Model} | Variables |
|---|---|
| onBeforeCreate{User} | request, params, data |
| onBeforeUpdate{User} | request, params, item |
| onBeforeDelete{User} | request, params, query |
| onBeforePaginate{User} | request, params, query |
| onBeforeShow{User} | request, params, query |
| onAfterCreate{User} | request, params, data, item |
| onAfterUpdate{User} | request, params, item |
| onAfterDelete{User} | request, params, item |
| onAfterPaginate{User} | request, params, result |
| onAfterShow{User} | request, params, item |
# Actions
The main difference between Actions and Events is; events are asynchronous. It means that if you are using an action and handle the request, the HTTP request cycle waits for you to do your task. But in events, when you handle the event, the HTTP requests cycle keeps working and returns a response. So, if you want to send an e-mail to the user, you should use Events. On the other hand, if you want to be involved in the query or any business logic in the HTTP request cycle, you should use Actions.
Using Actions is very easy. The only thing you do, you should create an Action file for your model under the directory app/Actions.
// app/Actions/UserActions.js
module.exports = {
async onBeforePaginate ({ request, params, query }) {
// Implement your business logic in here.
}
}
If you create an action file like this, every time before pagination of User.js model, this method will be triggered. The only thing you should care about is using the same naming structure for model and action file;
| Model | Actions |
|---|---|
| User.js | UserActions.js |
| Users.js | UsersActions.js |
| UserPost.js | UserPostActions.js |
Actions are loaded in the initialization process at *once. So your action methods should be stateless.
You can handle every action on models. Please look at the following tables;
| ActionName | Variables |
|---|---|
| onBeforeCreate | request, params, data |
| onBeforeUpdateQuery | request, params, query |
| onBeforeUpdate | request, params, item |
| onBeforeDelete | request, params, query |
| onBeforePaginate | request, params, query |
| onBeforeShow | request, params, query |
| onAfterCreate | request, params, data, item |
| onAfterUpdateQuery | request, params, item |
| onAfterUpdate | request, params, item |
| onAfterDelete | request, params, item |
| onAfterPaginate | request, params, result |
| onAfterShow | request, params, item |
# Variables
There are some variables which you can use in a trigger or event function;
← Queries