@networkoptix/request-interceptor v0.1.1
Request Interceptor
What is @networkoptix/request-intereptor
?
This package allows intercepting request and applying middleware that can modify the request before it is handled by the browser/node or to modify a response before it's return back to the application.
What can it do?
The RequestInterceptor
class handles handles registering middleware that intercepts
requests and responses.
The middleware classes are all derived from the RequestMiddleware
class. They can be configured
to handle requests, responses, or both.
The middleware applied to the requests/reponses in the order that they are declared.
Usage
The RequestInterceptor
class exposes a register
static method which is used to initialize
the interceptor. This method accepts an array of RequestMiddleware
to apply to requests/responses.
Middleware
Included in the package are abstract and concrete classes for handling common use cases.
Generally concrete class names start with the word With
to make it clear if it's an abstract or
concrete class. So SomeMiddleware
would be an abstract class and WithAnotherMiddleware
would
be a concrete class.
Abstract Middleware
An example abstract middleware class would be the AuthenticationMiddleware
which defines
shouldAuthenticate
and authenticate
classes and simplifies creating concrete middleware
that handles various authentication schemes.
Concrete Middleware
An example abstract middleware class would be the WithBearerMiddleware
which defines specific
implementation of the shouldAuthenticate
and authenticate
methods to handle bearer
token authentication.
Nx Meta Middleware
The Nx Meta
middleware are specialized for interacting with Nx Meta
services. These middleware
classes will start with either Nx
for abstract classes or WithNx
for concrete classes.
Example of creating custom middleware from abstract class:
import { AuthenticationMiddleware } from '@networkoptix/request-interceptor'
export class WithBearerMiddleware extends AuthenticationMiddleware {
async authenticate(request: Request): Promise<void> {
request.headers.set('authorization', `Bearer ${await this.getToken()}`);
}
constructor(
private getToken: (request?: Request) => string | Promise<string>,
protected shouldAuthenticate: (request?: Request) => boolean
) {
super();
}
}
Example usage of concrete middleware:
The interceptor should be registered as early in the application lifecycle as possible.
For most applications it would be included in a main.ts
or main.js
file or a polyfills file.
import { WithBearerMiddleware, RequestInterceptor } from '@networkoptix/request-interceptor'
import { getToken, shouldAuthenticate } './from-other-module'
const middlewares = [
new WithBearerMiddleware(getToken, shouldAuthenticate)
]
RequestInterceptor.register(middlewares)