A generic chain-of-responsibility pattern with promises.
npm install promise-filter-chainA generic filter-chain with promises. Each filter returns a truthy value
to continue the chain. Each filter can read and manipulate an object passed
by reference as the first argument.
``
npm install --save promise-filter-chain
`javascript
const FilterChain = require('promise-filter-chain');
// filter to log http events
const eventLogger = {
process: event => {
const { request } = event;
console.log(${request.httpMethod} ${request.path});
return Promise.resolve(true);
}
};
// filter to authenticate http events
const authenticator = {
process: event => {
if (event.request.headers.Cookie['user-id'] !== 'authenticated user') {
event.response.statusCode = 403;
return Promise.resolve(false);
} else {
return Promise.resolve(true);
}
}
};
// filter chain for all requests
const filterChain = new FilterChain([
eventLogger,
authenticator
]);
// handler for a some API endpoint
const controller = {
process: event => {
event.response.statusCode = 200;
// retrieve some data from business logic
// respond to http request:
event.response.body = {
name: 'Corey',
awesome: true
};
}
}
// process an http event
return filterChain.wrapInChain(incomingHttpEvent, controller);
``