Dependency injection support for fastify framework, using awilix.
First install the package and awilix:
npm i @fastify/awilix awilixNext, set up the plugin:
const { fastifyAwilixPlugin } = require('@fastify/awilix')
const fastify = require('fastify')
app = fastify({ logger: true })
app.register(fastifyAwilixPlugin, {
disposeOnClose: true,
disposeOnResponse: true,
strictBooleanEnforced: true
})Then, register some modules for injection:
const {
diContainer, // this is an alias for diContainerProxy
diContainerClassic, // this instance will be used for `injectionMode = 'CLASSIC'`
diContainerProxy // this instance will be used by default
} = require('@fastify/awilix')
const { asClass, asFunction, Lifetime } = require('awilix')
// Code from the previous example goes here
diContainer.register({
userRepository: asClass(UserRepository, {
lifetime: Lifetime.SINGLETON,
dispose: (module) => module.dispose(),
}),
})
app.addHook('onRequest', (request, reply, done) => {
request.diScope.register({
userService: asFunction(
({ userRepository }) => {
return new UserService(userRepository, request.params.countryId)
},
{
lifetime: Lifetime.SCOPED,
dispose: (module) => module.dispose(),
}
),
})
done()
})Note that there is no strict requirement to use classes, it is also possible to register primitive values, using either asFunction(), or asValue(). Check awilix documentation for more details.
After all the modules are registered, they can be resolved with their dependencies injected from app-scoped diContainer and request-scoped diScope. Note that diScope allows resolving all modules from the parent diContainer scope:
app.post('/', async (req, res) => {
const userRepositoryForReq = req.diScope.resolve('userRepository')
const userRepositoryForApp = app.diContainer.resolve('userRepository') // This returns exact same result as the previous line
const userService = req.diScope.resolve('userService')
// Logic goes here
res.send({
status: 'OK',
})
})injectionMode - whether to use PROXY or CLASSIC injection mode. See awilix documentation for details. Default is 'PROXY'.
container - pre-created AwilixContainer instance that should be used by the plugin. By default plugin uses its own instance. Note that you can't specify both injectionMode and container parameters at the same time.
disposeOnClose - automatically invoke configured dispose for app-level diContainer hooks when the fastify instance is closed.
Disposal is triggered within onClose fastify hook.
Default value is true
disposeOnResponse - automatically invoke configured dispose for request-level diScope hooks after the reply is sent.
Disposal is triggered within onResponse fastify hook.
Default value is true
asyncInit - whether to process asyncInit fields in DI resolver configuration. Note that all dependencies with asyncInit enabled are instantiated eagerly. Disabling this will make app startup slightly faster.
Default value is false
asyncDispose - whether to process asyncDispose fields in DI resolver configuration when closing the fastify app. Disabling this will make app closing slightly faster.
Default value is false
eagerInject - whether to process eagerInject fields in DI resolver configuration, which instantiates and caches module immediately. Disabling this will make app startup slightly faster.
Default value is false
strictBooleanEnforced - whether to throw an error if enabled field in a resolver configuration is set with unsupported value (anything different from true and false). It is recommended to set this to true, which will be a default value in the next semver major release.
Default value is false
All dependency modules are resolved using either the constructor injection (for asClass) or the function argument (for asFunction), by passing the aggregated dependencies object, where keys
of the dependencies object match keys used in registering modules:
class UserService {
constructor({ userRepository }) {
this.userRepository = userRepository
}
dispose() {
// Disposal logic goes here
}
}
class UserRepository {
constructor() {
// Constructor logic goes here
}
dispose() {
// Disposal logic goes here
}
}
diContainer.register({
userService: asClass(UserRepository, {
lifetime: Lifetime.SINGLETON,
dispose: (module) => module.dispose(),
}),
userRepository: asClass(UserRepository, {
lifetime: Lifetime.SINGLETON,
dispose: (module) => module.dispose(),
}),
})By default @fastify/awilix is using generic empty Cradle and RequestCradle interfaces, it is possible extend them with your own types:
awilix defines Cradle as a proxy, and calling getters on it will trigger a container.resolve for an according module. Read more
declare module '@fastify/awilix' {
interface Cradle {
userService: UserService
}
interface RequestCradle {
user: User
}
}
//later, type is inferred correctly
fastify.diContainer.cradle.userService
// or
app.diContainer.resolve('userService')
// request scope
request.diScope.resolve('userService')
request.diScope.resolve('user')Find more in tests or in example from awilix documentation
fastify-awilix supports extended awilix resolver options, provided by awilix-manager:
const { diContainer, fastifyAwilixPlugin } = '@fastify/awilix'
const { asClass } = require('awilix')
diContainer.register(
'dependency1',
asClass(AsyncInitSetClass, {
lifetime: 'SINGLETON',
asyncInit: 'init',
asyncDispose: 'dispose',
eagerInject: true,
})
)
app = fastify()
await app.register(fastifyAwilixPlugin, { asyncInit: true, asyncDispose: true, eagerInject: true })
await app.ready()For more advanced use-cases, check the official awilix documentation
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