# View Engine
The Bogart `ViewEngine` renders view. It handles partials and layouts as well.
The `ViewEngine` ships with support for [Mustache](http://mustache.github.com/),
[Jade](http://jade-lang.com/), and [Haml](http://haml-lang.com/).
## view.viewEngine(engine)
Creates a `view.ViewEngine`.
## ViewEngine.render(template, [options])
The `render` method uses the selected templating engine to render the specified view
with options specified in the options `locals` object.
Rendering a view with mustache and replacement variables:
var viewEngine = bogart.viewEngine('mustache');
viewEngine.render('index.html', { locals: { title: 'Hello Mustache' } });
## ViewEngine.respond(template, [options])
The `respond` method returns a promise for a JSGI response that will render the
specified view.
var viewEngine = bogart.viewEngine('mustache');
viewEngine.respond('index.html', { locals: { title: 'Hello Mustache' } });
## view.RenderOptions
Options passed to `viewEngine.render` and `viewEngine.respond` should quack like view.RenderOptions.
* opts.layout The name of the layout or a boolean. If `true` then the name is defaulted to 'layout.html'. If `false` then no layout should be used.
* opts.locals Context in which to render the template. This should contain the replacement values of variables in your templates.
## Layouts
Layouts are supported. By default, if there is a file named 'layout.{ext}' where
`ext` is the extension of the view (haml, jade, mustache, html, etc...) then this file
is used as the layout for the view. The layout is expected to render a variable named
`body`. The `body` variable will contain the contents of view being rendered into the
layout. The `body` variable should not be HTML escaped.
Specifying the file extension of a template is optional as long as the file extension
matches the default file extension associated with the template type. For example, if
using Jade then `viewEngine.render('index')` is equivalent to `viewEngine.render('index.jade')`.
### Mustache Example
Mustache is the default template engine of Bogart.
View (index.html):
Welcome {{firstName}}!
Layout (layout.html):
{{title}}
{{title}}
{{{body}}}
App (app.js):
var bogart = require('bogart');
var viewEngine = bogart.viewEngine('mustache');
var router = bogart.router();
router.get('/hello/:firstName', function(req) {
return viewEngine.respond('index.html', {
locals: { title: 'Hello', firstName: req.params.firstName }
});
});
bogart.start(router);
Execute `node app.js` and visit [http://localhost:8080/hello/bogart](http://localhost:8080/hello/bogart).
### Jade Example
Make sure to install bogart-jade from npm before running these examples.
View (index.jade):
Welcome #{firstName}!
Layout (layout.jade):
html
head
title #{title}
body
h1 #{title}
!{body}
App (app.js):
var bogart = require('bogart');
var viewEngine = bogart.viewEngine('jade');
var router = bogart.router();
router.get('/hello/:firstName', function(req) {
return viewEngine.respond('index', {
locals: { title: 'Hello', firstName: req.params.firstName }
});
});
bogart.start(router);
Execute `node app.js` and visit [http://localhost:8080/hello/bogart](http://localhost:8080/hello/bogart).
## Partials
Sometimes, especially with AJAX requests, it is desirable to return a view without rendering it inside of a
layout even if a layout is present. To acccomodate this, the View Engine has a `partial` method. The `partial`
method takes the same arguments as the `render` method but does not render its template insdie of
a layout.
var viewEngine = bogart.viewEngine('mustache');
viewEngine.partial('index.html');