-
Notifications
You must be signed in to change notification settings - Fork 1.1k
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
docs: migrate missing pages from loopback.io
- Loading branch information
Showing
18 changed files
with
978 additions
and
248 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,238 @@ | ||
--- | ||
lang: en | ||
title: 'Booting an Application' | ||
keywords: LoopBack 4.0, LoopBack 4 | ||
tags: | ||
sidebar: lb4_sidebar | ||
permalink: /doc/en/lb4/Booting-an-Application.html | ||
summary: | ||
--- | ||
|
||
## What does Booting an Application mean? | ||
|
||
A typical LoopBack application is made up of many artifacts in different files, | ||
organized in different folders. **Booting an Application** means: | ||
|
||
* Discovering artifacts automatically based on a convention (a specific folder | ||
containing files with a given suffix) | ||
* Processing those artifacts (this usually means automatically binding them to the Application's Context) | ||
|
||
`@loopback/boot` provides a Bootstrapper that uses Booters to automatically | ||
discover and bind artifacts, all packaged in an easy-to-use Mixin. | ||
|
||
### What is an artifact? | ||
|
||
An artifact is any LoopBack construct usually defined in code as a Class. LoopBack | ||
constructs include Controllers, Repositories, Models, etc. | ||
|
||
## Usage | ||
|
||
### @loopback/cli | ||
|
||
New projects generated using `@loopback/cli` or `lb4` are automatically enabled | ||
to use `@loopback/boot` for booting the Application using the conventions | ||
followed by the CLI. | ||
|
||
### Adding to existing project | ||
|
||
See [Using the BootMixin](#using-the-bootmixin) to add Boot to your Project manually. | ||
|
||
--- | ||
|
||
The rest of this page describes the inner workings of `@loopback/boot` for advanced use | ||
cases, manual usage or using `@loopback/boot` as a standalone package (with custom | ||
booters). | ||
|
||
## BootMixin | ||
|
||
Boot functionality can be added to a LoopBack 4 Application by mixing it with the | ||
`BootMixin`. The Mixin adds the `BootComponent` to your Application as well as | ||
convenience methods such as `app.boot()` and `app.booters()`. The Mixin also allows | ||
Components to set the property `booters` as an Array of `Booters`. They will be bound | ||
to the Application and called by the `Bootstrapper`. | ||
|
||
Since this is a convention-based Bootstrapper, it is important to set a `projectRoot`, | ||
as all other artifact paths will be resolved relative to this path. | ||
|
||
_Tip_: `application.ts` will likely be at the root of your project, so its path can be | ||
used to set the `projectRoot` by using the `__dirname` variable. _(See example below)_ | ||
|
||
### Using the BootMixin | ||
|
||
`Booter` and `Binding` types must be imported alongside `BootMixin` to allow TypeScript | ||
to infer types and avoid errors. _If using `tslint` with the `no-unused-variable` rule, | ||
you can disable it for the import line by adding `// tslint:disable-next-line:no-unused-variable` | ||
above the import statement_. | ||
|
||
```ts | ||
import {BootMixin, Booter, Binding} from "@loopback/boot"; | ||
|
||
class MyApplication extends BootMixin(Application) { | ||
constructor(options?: ApplicationConfig) { | ||
super(options); | ||
// Setting the projectRoot | ||
this.projectRoot = __dirname; | ||
// Set project conventions | ||
this.bootOptions: BootOptions = { | ||
controllers: { | ||
dirs: ['controllers'], | ||
extensions: ['.controller.js'], | ||
nested: true, | ||
} | ||
} | ||
} | ||
} | ||
``` | ||
|
||
Now just call `app.boot()` from `index.ts` before starting your Application using `app.start()`. | ||
|
||
#### app.boot() | ||
|
||
A convenience method to retrieve the `Bootstrapper` instance bound to the | ||
Application and calls its `boot` function. This should be called before an | ||
Application's `start()` method is called. _This is an `async` function and should | ||
be called with `await`._ | ||
|
||
```ts | ||
class MyApp extends BootMixin(Application) {} | ||
|
||
async main() { | ||
const app = new MyApp(); | ||
app.projectRoot = __dirname; | ||
await app.boot(); | ||
await app.start(); | ||
} | ||
``` | ||
|
||
#### app.booters() | ||
|
||
A convenience method to manually bind `Booters`. You can pass any number of `Booter` | ||
classes to this method and they will all be bound to the Application using the | ||
prefix (`booters.`) and tag (`booter`) used by the `Bootstrapper`. | ||
|
||
```ts | ||
// Binds MyCustomBooter to `booters.MyCustomBooter` | ||
// Binds AnotherCustomBooter to `booters.AnotherCustomBooter` | ||
// Both will have the `booter` tag set. | ||
app.booters(MyCustomBooter, AnotherCustomBooter); | ||
``` | ||
|
||
## BootComponent | ||
|
||
This component is added to an Application by `BootMixin` if used. This Component: | ||
|
||
* Provides a list of default `booters` as a property of the component | ||
* Binds the conventional Bootstrapper to the Application | ||
|
||
_If using this as a standalone component without the `BootMixin`, you will need to | ||
bind the `booters` of a component manually._ | ||
|
||
```ts | ||
app.component(BootComponent); | ||
``` | ||
|
||
## Bootstrapper | ||
|
||
A Class that acts as the "manager" for Booters. The Bootstrapper is designed to be | ||
bound to an Application as a `SINGLETON`. The Bootstrapper class provides a `boot()` | ||
method. This method is responsible for getting all bound `Booters` and running | ||
their `phases`. A `phase` is a method on a `Booter` class. | ||
|
||
Each `boot()` method call creates a new `Context` that sets the `app` context | ||
as its parent. This is done so each `Context` for `boot` gets a new instance of | ||
`booters` but the same context can be passed into `boot` so selective `phases` can be | ||
run in different calls of `boot`. | ||
|
||
The Bootstrapper can be configured to run specific booters or boot phases | ||
by passing in `BootExecOptions`. **This is experimental and subject to change. Hence, | ||
this functionality is not exposed when calling `boot()` via `BootMixin`**. | ||
|
||
To use `BootExecOptions`, you must directly call `bootstrapper.boot()` instead of `app.boot()`. | ||
You can pass in the `BootExecOptions` object with the following properties: | ||
|
||
| Property | Type | Description | | ||
| ---------------- | ----------------------- | ------------------------------------------------ | | ||
| `booters` | `Constructor<Booter>[]` | Array of Booters to bind before running `boot()` | | ||
| `filter.booters` | `string[]` | Names of Booter classes that should be run | | ||
| `filter.phases` | `string[]` | Names of Booter phases to run | | ||
|
||
### Example | ||
|
||
```ts | ||
import { BootMixin, Booter, Binding, Bootstrapper } from "@loopback/boot"; | ||
|
||
class MyApp extends BootMixin(Application) {} | ||
const app = new MyApp(); | ||
app.projectRoot = __dirname; | ||
|
||
const bootstrapper: Bootstrapper = await this.get( | ||
BootBindings.BOOTSTRAPPER_KEY | ||
); | ||
bootstrapper.boot({ | ||
booters: [MyCustomBooter], | ||
filter: { | ||
booters: ["MyCustomBooter"], | ||
phases: ["configure", "discover"] // Skip the `load` phase. | ||
} | ||
}); | ||
``` | ||
|
||
## Booters | ||
|
||
A Booter is a class that is responsible for booting an artifact. A Booter does its | ||
work in `phases` which are called by the Bootstrapper. The following Booters are | ||
a part of the `@loopback/boot` package and loaded automatically via `BootMixin`. | ||
|
||
### Controller Booter | ||
|
||
This Booter's purpose is to discover [Controller](Controllers.html) type Artifacts and to bind | ||
them to the Application's Context. | ||
|
||
You can configure the conventions used in your | ||
project for a Controller by passing a `controllers` object on `BootOptions` property | ||
of your Application. The `controllers` object supports the following options: | ||
|
||
| Options | Type | Default | Description | | ||
| ------------ | -------------------- | -------------------- | ------------------------------------------------------------------------------------------------------------- | | ||
| `dirs` | `string \| string[]` | `['controllers']` | Paths relative to projectRoot to look in for Controller artifacts | | ||
| `extensions` | `string \| string[]` | `['.controller.js']` | File extensions to match for Controller artifacts | | ||
| `nested` | `boolean` | `true` | Look in nested directories in `dirs` for Controller artifacts | | ||
| `glob` | `string` | | A `glob` pattern string. This takes precendence over above 3 options (which are used to make a glob pattern). | | ||
|
||
### Repository Booter | ||
|
||
This Booter's purpose is to discover [Repository](Repository.html) type Artifacts and to bind | ||
them to the Application's Context. The use of this Booter requires `RepositoryMixin` | ||
from `@loopback/repository` to be mixed into your Application class. | ||
|
||
You can configure the conventions used in your | ||
project for a Repository by passing a `repositories` object on `BootOptions` property | ||
of your Application. The `repositories` object supports the following options: | ||
|
||
| Options | Type | Default | Description | | ||
| ------------ | -------------------- | -------------------- | ------------------------------------------------------------------------------------------------------------- | | ||
| `dirs` | `string \| string[]` | `['repositories']` | Paths relative to projectRoot to look in for Repository artifacts | | ||
| `extensions` | `string \| string[]` | `['.repository.js']` | File extensions to match for Repository artifacts | | ||
| `nested` | `boolean` | `true` | Look in nested directories in `dirs` for Repository artifacts | | ||
| `glob` | `string` | | A `glob` pattern string. This takes precendence over above 3 options (which are used to make a glob pattern). | | ||
|
||
### Custom Booters | ||
|
||
A custom Booter can be written as a Class that implements the `Booter` interface. The Class | ||
must implement methods that corresponds to a `phase` name. The `phases` are called | ||
by the Bootstrapper in a pre-determined order (unless overridden by `BootExecOptions`). | ||
The next phase is only called once the previous phase has been completed for all Booters. | ||
|
||
#### Phases | ||
|
||
**configure** | ||
|
||
Used to configure the `Booter` with its default options. | ||
|
||
**discover** | ||
|
||
Used to discover the artifacts supported by the `Booter` based on convention. | ||
|
||
**load** | ||
|
||
Used to bind the discovered artifacts to the Application. |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.