Route composition

As we know - every API requires composable routing. Lets assume that we have a separate User feature where its API endpoints respond to GET and POST methods on /user path.

r.pipe is an indexed monad builder used for collecting information about Marble REST route details, like: path, request method type, middlewares and connected Effect.

import { combineRoutes, r } from '@marblejs/core';
​
const getUsers$ = r.pipe(
  r.matchPath('/'),
  r.matchType('GET'),
  r.useEffect(req$ => req$.pipe(
    // ...
  )));
​
const postUser$ = r.pipe(
  r.matchPath('/'),
  r.matchType('POST'),
  r.useEffect(req$ => req$.pipe(
    // ...
  )));
​
export const user$ = combineRoutes('/user', [
  getUsers$,
  postUser$,
]);

Route effects can be grouped together using combineRoutes function, which combines routing for a prefixed path passed as a first argument. Exported group of Effects can be combined with other Effects like in the example below.

import { combineRoutes, r } from '@marblejs/core';
import { user$ } from './user.effects';
​
const root$ = r.pipe(
  r.matchPath('/'),
  r.matchType('GET'),
  r.useEffect(req$ => req$.pipe(
    // ...
  )));
​
const foo$ = r.pipe(
  r.matchPath('/foo'),
  r.matchType('GET'),
  r.useEffect(req$ => req$.pipe(
    // ...
  )));
​
export const api$ = combineRoutes('/api/v1', [
  root$,
  foo$,
  user$, // 👈
]);

As you can see, the previously defined routes can be combined together, so as a result the routing is built in a much more structured way. If we analyze the above example, the routing will be mapped to the following routing table.

GET    /api/v1
GET    /api/v1/foo
GET    /api/v1/user
POST   /api/v1/user

There are some cases where there is a need to compose a bunch of middlewares before grouped routes, e.g. to authenticate requests only for a selected group of endpoints. Instead of composing middlewares using use operator for each route separately, you can compose them via the extended second parameter incombineRoutes() function.

import { combineRoutes } from '@marblejs/core';
​
const user$ = combineRoutes('/user', {
  middlewares: [authorize$],
  effects: [getUsers$, postUser$],
});

Body parameters

Marble.js doesn't come with a built-in mechanism for parsing POST, PUT and PATCH request bodies. In order to get the parsed request body you can use dedicated @marblejs/middleware-body package. A new req.body object containing the parsed data will be populated on the request object after the middleware, or undefined if there was no body to parse, the Content-Type was not matched, or an error occurred. To learn more about body parsing middleware visit the @marblejs/middleware-body API specification.

URL parameters

The combineRoutes function and the matchPath allows you to define parameters in the path argument. All parameters are defined by the syntax with a colon prefix.

import { r } from '@marblejs/core';
​
const foo$ = r.pipe(
  r.matchPath('/:foo/:bar'),
  // ...
);

Decoded path parameters are placed in the req.params property. If there are no decoded URL parameters then the property contains an empty object. For the above example and route /bob/12 the req.params object will contain the following properties:

{
  foo: 'bob',
  bar: '12',
}

For parsing and decoding URL parameters, Marble.js makes use of path-to-regexp library.

Path parameters can be suffixed with an asterisk (*) to denote a zero or more parameter matches. The code snippet below shows an example use case of a "zero-or-more" parameter. For example, it can be useful for defining routing for static assets.

import { r } from '@marblejs/core';
import { map, mergeMap } from 'rxjs/operators';
​
const getFile$ = r.pipe(
  r.matchPath('/:dir*'),
  r.matchType('GET'),
  r.useEffect(req$ => req$.pipe(
    // ...
    map(req => req.params.dir),
    mergeMap(readFile(STATIC_PATH)),
    map(body => ({ body }))
  )));

Query parameters

Except intercepting URL params, the routing is able to parse query parameters provided in path string. All decoded query parameters are located inside req.query property. If there are no decoded query parameters then the property contains an empty object. For parsing and decoding query parameters, Marble.js makes use of qs library.

Example 1:

GET /user?name=Patrick

req.query = {
  name: 'Patrick',
};

Example 2:

GET /user?name=Patrick&location[country]=Poland&location[city]=Katowice

req.query = {
  name: 'Patrick',
  location: {
    country: 'Poland',
    city: 'Katowice',
  },
};