middleware flow control
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Type Name Latest commit message Commit time
Failed to load latest commit information.
lib
test
.eslintignore
.eslintrc
.gitignore
.travis.yml
LICENSE
README.md
index.js
package.json

README.md

middleware-flow Build Status

Middleware control flow library

Installation

npm install middleware-flow

Examples

series(middlewares...)

var series = require('middleware-flow').series;
var app = require('express')();

app.use(series(mw1, mw2, mw2)); // equivalent to app.use(mw1, mw2, mw3);

parallel(middlewares...)

var parallel = require('middleware-flow').parallel;
var app = require('express')();
                                  // runs the middlewares in 'parallel'
app.use(parallel(mw1, mw2, mw2)); // if err, returns the first error that occurred

parallelWait(middlewares...)

var parallelWait = require('middleware-flow').parallelWait;
var app = require('express')();
                                  // runs the middlewares in 'parallel' and waits for all of them before to return also in case of err
app.use(parallelWait(mw1, mw2, mw2)); // if err, returns the first error that occurred

each

var each = require('middleware-flow').each;
var arr = [1,2,3];
var app = require('express')();
                                  // runs the middlewares in 'parallel'
app.use(
  each(arr,
    // runs the middlewares in parallel
    function (eachReq, res, next) {
      // eachReq is a scoped req for the each function that reads from req,
      // but writes to it's own scope (prototypically inherits from request)
    },
    function (item, req, eachReq, res, next) {
      // if middleware accepts five arguments, the current item and the original req are passed
      // eachReq is a scoped req for the each function that reads from req,
      // but writes to it's own scope (prototypically inherits from request)
    })
); // if err, returns the first error that occurred

or(middlewares...)

var or = require('middleware-flow').or;
var app = require('express')();
                                             // runs the middlewares in series, until one passes (no next(err));
app.use(or(user.isOwner, user.isModerator)); // if err, returns the first error that occurred

and(middlewares...)

Same as series.

if(value).then(middlewares...).else(middlewares...)

var if = require('middleware-flow').if;
var app = require('express')();

app.use(
  if(true)
    .then(one, two, three)
    .else(error)
);

syncIf(fn).then(middlewares...).else(middlewares...)

var syncIf = require('middleware-flow').syncIf;
var app = require('express')();

app.use(
  syncIf(nameQueryExists)   // accepts a sync function that returns a boolean
    .then(one, two, three)  // true -> then, error -> skips all next(err)
    .else(error)
);
function nameQueryExists (req, res) {
  return exists(req.query.name);
}
function exists (val) {
  return val !== null && val !== undefined;
}

asyncIf(fn).then(middlewares...).else(middlewares...)

var asyncIf = require('middleware-flow').asyncIf;
var or = require('middleware-flow').or;
var fs = require('fs');
var app = require('express')();

app.use(
  asyncIf(bodyFileExists)    // expects boolean as the result argument
    .then(one, two, three)   // true -> then, false -> else, error -> skips all next(err)
    .else(other)
);
function logExists (req, res, cb) {
  fs.exists(req.body.file, function (exists) {
    cb(null, exists);
  });
}

mwIf(middleware).then(middlewares..).else(middlewares..)

var mwIf = require('middleware-flow').mwIf;
var app = require('express')();

app.use(
  mwIf(userIsModerator)    // error here, just runs the else middlewares
    .then(one, two, three) // no error -> then, error -> else
    .else(other)           // if other is an error middleware it will recieve
                           //   the error else the error will be ignored
);
function userIsModerator (req, res, next) {
  if (!req.user.isModerator) {
    next(new Error('access denied'));
  }
  else {
    next();
  }
}

try(middlewares..).catch(middlewares..)

var flow = require('middleware-flow');
var app = require('express')();

app.use(
  flow.try(saveUser) // error here, just runs the catch middlewares
    .catch(rollback) // no error -> other, error -> rollback
                     // if rollback is an error middleware it will recieve
                     //   the error else the error will be ignored
);
function saveUser (req, res, next) {
  db.save(req.user, next);
}

bg(middlewares...)

app.use(
  flow.bg(mw1, mw2, mw2)
); // runs the middlewares in series in the background

License

MIT