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# Express-Streamline

Patch for [Express](http://expressjs.com/) to add support for
[Streamline](https://github.com/Sage/streamlinejs) syntax in Express apps.

Supports Express 2 through 5.

## Example

```js
var express = require('express-streamline');
var app = express();

// ...

app.use(function (req, res, _) {
    if (req.session.userId) {
        req.currentUser = User.getById(req.session.userId, _);
    }
});

// ...

app.get('/photos', function (req, res, _) {
    var photos = req.currentUser.getPhotos(_);
    res.render('photos', {
        photos: photos,
    });
});
```

## Installation

```
npm install express-streamline --save
```

## Usage

You can either `require()` Express normally and then patch it:

```js
var express = require('express');
require('express-streamline');
```

Or just `require()` this module, which returns the patched Express for
convenience:

```js
var express = require('express-streamline');
```

Then, you can write any and all Express handlers in Streamline syntax by just
replacing `next` with `_`.

```js
// middleware handlers:
app.use(function (req, res, _) { ... });
app.param('user', function (req, res, _, user) { ... });

// route handlers:
app.get('/:user', function (req, res, _) { ... });
app.post('/:user', function (req, res, _) { ... });
// ... (all verbs supported)

// error handlers:
app.use(function (err, req, res, _) { ... });
```

By default, Streamlined middleware handlers will continue to the `next`
middleware, while Streamlined route and error handlers won't.
This is generally what you want, but **you can specify whether `next` is
called by explicitly returning `true` or `false`**.

```js
// middleware to blacklist banned IP addresses,
// but allow all other requests to pass through:
app.use(function (req, res, _) {
    var isBanned = db.bannedIPs.search(req.ips, _).length > 0;
    if (isBanned) {
        res.send(403);
        return false;   // end the response
    }
});
```

This module also supports Streamline's smart
[global context](https://github.com/Sage/streamlinejs/blob/master/lib/globals.md).
If present, the context is reset for every request, so data can safely be
added to it without affecting other requests.

```js
var globals = require('streamline/lib/globals');

// middleware to set a global `locale` variable on every request,
// for lower-level modules to use:
app.use(function (req, res, __) {
    // parse locale... then:
    globals.context.locale = locale;
});
```

If you run into any issues, [file a bug](https://github.com/aseemk/express-streamline/issues/)!

## Changelog

See [CHANGELOG.md](./CHANGELOG.md).

## License

MIT. © 2012-2015 Aseem Kishore.

## Credits

[TJ Holowaychuk](https://github.com/visionmedia) for the awesome Express, and
[Bruno Jouhier](https://github.com/bjouhier) for the awesome Streamline.

[Seth Yuan](https://github.com/sethyuan)'s
[`streamline-express`](https://github.com/sethyuan/streamline-express) for the
inspiration and motivation.
`streamline-express` has supported Express 3 for longer than this module, and
it currently also supports more advanced Express 3 features (like passing
multiple Streamlined handlers to the same `app.verb` call).
I believe this module has a cleaner API and more robust implementation,
however, but I'm biased. =) Both modules get the job done just fine!