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Migration to ZappaJS 0.4

Zappa 0.4 uses Express 3.0 while Zappa 0.3 uses Express 2.5. The new version of Express is not backward-compatible and breaks Zappa in places. Here are the differences we know about.

  • Most template engines do not support the new Express 3.x conventions at this time; if you want to use them you should for example:

    @engine 'eco', require('consolidate').eco

    or (works alongside Zappa's databag option)

    @engine 'eco', zappa.adapter 'eco'

    Since register was removed in Express 3.x it is therefor no longer available in Zappa 0.4.

  • Layout and partials support was removed from Express 3.x, and is no longer available in vanilla zappa 0.4.

    To continue using layout or partials in zappa 0.4 you must

    @use 'partials'

    This will require that you have the zappa-partials module installed in your application. (This module is an extended version of express-partials with support for multiple instances, pending integration in mainline.)

  • Express 3.0 is no longer a subclass of the Node.js HTTP server. The server object is available as @server; @app.listen is now @server.listen.

Other changes are Zappa-specific and simplify the API:

  • If you built variadic helpers in Zappa 0.3 you might have been aware of an undocumented, extraneous parameter (the context) provided to the helpers.

    That extraneous argument has been removed since it is a duplicate of this. Helper functions now receive the arguments provided by the caller unmodified.

  • No argument (the databag or context) are passed to callbacks.

    This might apply to you if you used the databag option (see below) or you used the context argument instead of this.

    This applies to (server-side) @get, @post, @put, @del, @all, all middleware functions, and @on. This applies to (client-side) @get (use @params) and @on (use @data).

    For example, if your code said:

    @get '/': (context) ->
  context.params

    replace it with

    @get '/': ->
  @params  # or this.params

  • The databag option has been modified.

    • It is now a boolean, use @enable 'databag' to activate it.
    • The databag is available as params (@params in coffeecup) to views. This is its only documented use.
    • All callbacks are called the same way whether databag is enabled or not. Callbacks no longer receive the context (@) or the databag as an argument.
    • If enabled, the databag is available as @data in request handlers and request middleware, but it is more efficient to use @req.param(name) than @data.name, since building the databag might be an expensive operation. Also @req.param() is available whether the databag setting is enabled or not.
    • If you were using the object created by the databag setting:
      • Server-side, for @get, @post, ... and for middleware use @req.param(). For @on use @data.
      • Client-side, for @get use @params, and for @on use @data.
    • The param option value for the databag setting is now the enabled state of the databag setting.
    • The this option value for the databag setting has been removed.