Services

By default service classes are located in APP_ROOT/services/**/* where APP_ROOT is the application base folder. The location can be changed using the servicesRoot configuration property. All service classes must be decorated with the @service decorator. The @service requires a string argument which defines the key to use when injecting the service using the @inject(...KEYS) decorator. By default each request gets its own instance of the injected service.

import { service } from 'kikwit';
@service('adder')
export class Adder {
    add(a, b) {
        return a + b;
    }
}

import { controller } from 'kikwit';
@inject('adder')
@controller
export class Arithm {   
    sum(context) {     
        let [a, b] = [7, 11];
        let sum = context.services.adder.add(a, b); // context.services.adder from @inject('adder')  
        return context.sendJSON({ a, b, sum });
    }
}

It is possible to get a service injected as a singleton by prefixing the key passed to the @inject(...KEYS) decorator with @.

import { service } from 'kikwit';
@service('adder')
export class Adder {   
    add(a, b) {
        return a + b;
    }
}

import { controller } from 'kikwit';
@inject('@adder') // '@adder' instead of 'adder'
@controller
export class Arithm {    
    sum(context) {        
        let [a, b] = [7, 11];
        let sum = context.services.adder.add(a, b); // context.services.adder from @inject('@adder')      
        return context.sendJSON({ a, b, sum });
    }
}

It is also possible to get the same instance of a service injected into an action across multiple requests by prefixing the key passed to the @inject(...KEYS) decorator with @@.

import { service } from 'kikwit';
@service('adder')
export class Adder {  
    add(a, b) {
        return a + b;
    }
}

import { controller } from 'kikwit';
@controller
export class Arithm {   
    @inject('@@adder') // '@@adder' instead of 'adder'
    sum(context) {      
        let [a, b] = [7, 11];
        let sum = context.services.adder.add(a, b); // context.services.adder from @inject('@@adder')  
        return context.sendJSON({ a, b, sum });
    }
}

In the example above, the instance injected into the sum action will only be reused by request to the sum action only.

To restrict a service to always be injected as a singleton, please pass true as a second argument to @service([KEY], [SINGLETON]) decorator.

import { service } from 'kikwit';
@service('adder', true)
export class Adder {  
    add(a, b) {
        return a + b;
    }
}

In the example above Adder will always get injected as a singleton regardless of how the format of the key used at the injection point.

Services injected at controller level are available to all of controller's actions.