react.di

Dependency injection for react based upon inversify.

• Installation
• Getting started
• Injection
  • Injection from class references
  • Injection via tokens
  • Multi injection
  • Inject into React Components
  • Inject into Services
• Sharing providers
  • Importing modules
  • Hierarchical shared providers
• Testing
• API
  • Injectable
  • Inject
  • Module
  • providers (Option)
    • Injecting a class constructor
    • Injecting a value
    • Injection via factories
  • imports (Option)
  • autoBindInjectable (Option)
  • TestBed (React Component)
  • Provider (React Component)

Installation

npm install react.di@next reflect-metadata --save

Your tsconfig.json needs to be configured with the following flags:

"experimentalDecorators": true,
"emitDecoratorMetadata": true

For version 1.0 see https://github.com/RobinBuschmann/react.di/tree/1.0

Getting started

1. Define injectables (values/class)

Service

import {Injectable, Inject} from 'react.di';

@Injectable
export class UserService {
  constructor(@Inject private httpClient: SomeHttpClient) {}

  getUser() {}
}

Config

const CONFIG_TOKEN = 'config'; // or Symbol('config');
const config: Config = {...};

2. Inject service/value into react component

import {Inject} from 'react.di';

class UserContainer extends Component<any, any> {
  @Inject userService: UserService;
  @Inject(CONFIG_TOKEN) config: Config;
  
  async componentDidMount() {
    const user = await this.userService.getUser();
    this.setState({user});
  }

  render() {
    return (<User user={this.state.user} />); 
  }
}

3. Setup module

import {Module} from 'react.di';

@Module({
  providers: [
    {provide: UserService, useClass: UserService},
    UserService, // or shorthand
    {provide: CONFIG_TOKEN, useValue: config},
    {provide: CONFIG_TOKEN, useFactory: context => config}, // or using factory
  ]
})
class App extends Component {
  render() {
    return (
        <Panel>
          <UserContainer/>
        </Panel>
    );
  }
}

Injection

Injection from class references

If you want to inject a service instance, simply mark the property with @Inject. The type from which the instance will be created, will be derived from the annotated type. Notice, that the type needs to be a class. An interface won't work, cause it will not exist on runtime anymore (See Injection via tokens to get it work with interfaces).

@Inject userService: UserService;

A services class need to be annotated with @Injectable otherwise it will not be - of course - injectable.

Injection via tokens

Dependencies can also be identified by a token. This makes sense when injecting a value (for example a configuration) or if you want annotate these properties with interfaces instead of class references.

@Inject(CONFIG_TOKEN) config: Config;

Multi injection

Multi injection means that all providers for a specified identifier will be injected. So if the annotated type of the dependency is of type Array, the injection will automatically processed as a multi-injection. In this case the identifier needs to be passed explicitly:

@Inject(INTERCEPTOR_TOKEN) interceptors: Interceptor[];

Inject into React Components

Dependencies of react component need be injected via property injection:

import {Inject} from 'react.di';

class UserComponent extends Component<any, any> {
  @Inject userService: UserService;
  @Inject(OtherService) otherService: OtherService;
  @Inject(CONFIG_TOKEN) config: Config;
  @Inject(TRANSLATION_TOKEN) translations: Translation[];
  
  ...
}

Inject into Services

Dependencies of services will be injected via constructor injection:

import {Injectable, Inject} from 'react.di';

@Injectable
export class UserService {
  constructor(@Inject http: HttpClient,
              @Inject(OtherService) otherService: OtherService,
              @Inject(HISTORY_TOKEN) history: IHistory) {}
}

Sharing providers

Providers can be shared via importing from siblings or inheriting them from parent components.

Importing modules in other modules

Modules can be imported in other modules to share its providers.

@Module({providers: [CommonService]})
class CommonModule extends Component {}

@Module({
  imports: [CommonModule],
  providers: [UserService],
})
class UserModule extends Component {
  @Inject userService: UserService;
  @Inject commonService: CommonService;
}

@Module()
class Root extends Component {
  render() {
    return (
      <UserModule/>
    );
  }

Hierarchical shared providers

Nesting Module annotated components in another Module annotated components is supported. All defined providers of the parent module will be inherited to its child modules:

@Module({providers: [UserService]})
class UserModule extends Component {}

@Module({providers: [CommonService]})
class App extends Component {
  render() {
    return (
      <UserModule/> // CommonService will also be available in UserModule
    );
  }

Providers that are already defined in a parent, will be overridden if they are also defined in its child.

Testing

For testing purposes react.di provides a TestBed component. Nest the components you want to test in TestBed and setup its dependencies in the providers prop of TestBed:

import {mount} from 'enzyme';

mount(
  <TestBed providers={[{provide: UserService, useClass: UserServiceMock}]}>
    <UserProfileContainer/>
  </TestBed>
);

or for defining a much simpler mock:

mount(
  <TestBed providers={[{provide: UserService, useValue: {getUser() {...}}}]}>
    <UserProfileContainer/>
  </TestBed>
);

API

Injectable

Injectable decorator marks a class as available to the inversify Container.

import {Injectable} from 'react.di';

@Injectable
export class UserService {}

Inject

The Inject/Inject(Identifier) decorator tells the di-system what need to be injected and in which property the injected value should be referenced.

Module

All components that should be feedable with the defined providers, need to be nested in a module annotated component - But don't(!) need to be direct children.

@Module({
  providers: [...],
  imports: [...],
  autoBindInjectable: true, // default is false
})
class App extends Component {}

providers (Option)

(optional) Array of all available providers.

Injecting a class constructor

[{provide: UserService, useClass: UserService}]

Shorthand

[UserService]

All instantiated dependencies will be a singleton by default. If you don't want a dependency to be singleton set noSingleton to true:

[{provide: UserService, useClass: UserService, noSingleton: true}]

Injecting a value

[{provide: UserService, useValue: someUserService}]

Injection via factories

Dependencies can be injected via factories. A factory is a simple function, that gets the context of the current scope and returns the value, that will be injected.

[{provide: UserService, useFactory: context => someValue}]

imports (Option)

(optional) Array of all modules that should be imported.

[CommonModule, UserModule]

autoBindInjectable (Option)

(optional, default: false) When autoBindInjectable is set to true, injectable class constructors don't need to be defined as providers anymore. They will be available for injection by default. So that [{provide: UserService, useClass: UserService}] or [UserService] can be omitted:

@Module({autoBindInjectable: true})
class App extends Component{}

<TestBed autoBindInjectable={true}>
  ... // UserService will be available anyway
</TestBed>

TestBed (React Component)

<TestBed providers={[...]} autoBindInjectable={true}>
  ...
</TestBed>

Provider (React Component)

The <Provider> component is a react component, that provides low-level support for inversifyJS containers. In other words: It takes an inversify container as property. So if you want to use all features of inversify, this is the component you will fall in love with:

const container = new Container();
container.bind(Ninja).to(Samurai);

<Provider container={container}>
  ...
</Provider>