Dependency injection for Typescript

Node module for DI in Typescript

It is lightweight and very easy to use.

To install it type:

``npm i justinject -S`

And it is necessary to enable:

"experimentalDecorators": true
"emitDecoratorMetadata": true

in tsconfig.json file

Example

`
@Service()
export class FirstService {
private time: any;

constructor() {
this.time = new Date();
}

public method() {
return this.time;
}
}

@Service()
export class SecondService {
constructor(public first: FirstService) { }

public method() {
return this.first.method();
}
}

import { Container } from 'justinject';
import { SecondService } from './SecondService';

const second = Container.resolve(SecondService);

console.log(second.method());
// retruns date
`

To specify Service as singleton add singelton key word in decorator
@Service('singleton')

Testing

To mock Service is pretty easy, example:

`
@Service()
export class FirstServiceMock extends FirstService{
private time: any;

constructor() {
this.time = new Date();
}

public method() {
return ${this.time} mocked;
}
}


Container.mock([
{
service: FirstService,
mockWith: FirstServiceMock,
override: false,
type: 'default'
}
])

const second = Container.resolve(SecondService);

console.log(second.method());
// retruns date mocked
`

HemeraJs Support

Hemera is node microservices framework. You can find more details here:
https://github.com/hemerajs/hemera

Justinject has support for hemera actions. You can declare new action like this:

`
@Service()
export class ActionService {
constructor(public hemera: HemeraService, public validate: ValidateService) { }

@Action({
topic: 'new.topic',
cmd: 'gogo'
}, { additionalPattern: 'dothat', newAdditionalPattern: 'dothis' })
public action(msg: any, done: any) {
console.log('Action message', msg.data);
done(null, 'Hemera action called!');
}
}
``

ActionService must have 2 properties hemera and validator.

HemeraService must have instance getter which returns Hemera instance.

ValidateService must have schema getter which returns validation.