Fastify decorators
Bootstrapping is the process of starting up, in this stage library initialize all controllers, services and their dependencies.
This Initialization is done before Fastify instance starts listen.
### Autoload all controllers
One of the options to bootstrap app is autoload feature, it uses path and mask to load controllers and/or handlers.
_Example_:
```ts
import { fastify } from 'fastify';
import { bootstrap } from 'fastify-decorators';
import { join } from 'path';
const app = fastify();
app.register(bootstrap, {
directory: __dirname,
mask: /\.controller\./,
});
```
### Specifying controllers list
Second option available is to specify all required controllers and/or handlers via array. This way you will have more granular control on whatever to load.
_Example_:
```ts
import { fastify } from 'fastify';
import { bootstrap } from 'fastify-decorators';
import { join } from 'path';
import MyController from './my-controller.js';
import { SecondController } from './second-controller.js';
const app = fastify();
app.register(bootstrap, {
controllers: [MyController, SecondController],
});
```
### Using custom class loader
By default, fastify-decorators uses own DI mechanism for getting controller instances.
This mechanism depends on `reflect-metadata` and provide basic abilities like constructor injection and injection to class fields via decorators.
You can read more about built-in DI at [Services and dependency injection](Services%20and%20dependency%20injection.md)
In case when built-in DI does not suitable it's possible to write own custom loader for classes and pass it via `classLoader` option.
Signature is `(clazz: Constructor) => C`.
```typescript
import 'reflect-metadata';
import { Container } from 'typedi';
app.register(bootstrap, {
// ...other options...
classLoader(clazz) {
return Container.get(clazz);
},
});
```
#### Limitations:
- It's not possible to use `getInstanceByToken` for getting `FastifyInstance` in static fields or decorators options:
```ts
import { Controller, FastifyInstanceToken, getInstanceByToken } from 'fastify-decorators';
@Controller()
class InstanceController {
// Will throw an error when bootstrap via controllers list
// This happens because "FastifyInstance" not available before "bootstrap" call but required when controller imported
static instance = getInstanceByToken(FastifyInstanceToken);
}
```