trailpack

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Trailpack Interface. Trailpacks extend the capability of the Trails
framework. (Application functionality should be extended using
Services).

Usage

This class should be extended by all trailpacks. Override the trailpack API
methods.

``js
const Trailpack = require('trailpack')

class ExampleTrailpack extends Trailpack {

/**
* Configure the lifecycle of this trailpacks.
*/
get lifecycle () {
return {
initialize: {

/**
* Only initialize this trailpack after trailpack-router has been
* initialized.
*/
listen: [ 'trailpack:router:initialize' ]
}
}
}

validate () {
if (!this.app.config.example) throw new Error('config.example not set!')
}

configure () {
this.app.config.example.happy = true
}

initialize () {
this.interval = setInterval(() => {
this.log.debug('happy?', this.app.config.example.happy)
}, 1000)
}

unload () {
clearInterval(this.interval)
}

constructor (app) {
super(app, {
config: require('./config'),
api: require('./api'),
pkg: require('./package')
})
}

}
`

API

$3

0. trails:start (event)
1. validate()
2. configure()
3. initialize()
4. trails:ready

$3

#### log
Provides convenient access to the Trails logger. (e.g. this.log.debug('hello'))

#### packs
Access the application's loaded Trailpacks. This is a mapping of
name -> Trailpack. (e.g. this.packs.core)

#### on, once, emit, after
Emit/Listen for events on the Trails EventEmitter. Convenience methods for
this.app.on, this.app.once, etc. (e.g. this.emit('custom:event'))

$3

#### constructor(app, definition)
Instantiate the Trailpack. definition is an object which contains three
optional properties: config, api, pkg. Trailpack configuration is merged
into the application configuration.

#### validate()
Validate the preconditions for proper functioning of this trailpack. For
example, if this trailpack requires that a database is configured in
config/stores.js, this method should validate this. This method should incur
no side-effects. Do not alter any extant configuration.

#### configure()
Alter/Extend the configuration (app.config) of the application, or
add new sections to the config object for the trailpack. This method
is run before the application is loaded -- after validate, and before
initialize. Trails does not allow further configuration changes after
this lifecycle stage is complete.

#### initialize()
If you need to bind any event listeners, start servers, connect to databases,
all of that should be done in initialize. The app's configuration is guaranteed to be
loaded and finalized before this stage.

#### unload()
Cleaup any resources/daemons started by this Trailpack. Used by trailpack-autoreload
and other system tools to cleanly release resources in order to
shutdown/restart the Trails application.

$3


The trailpack type is used to distinguish between Trailpacks by the role they
perform in the application. It is also used by developer tools such as Trailmix

#### system
These trailpacks provide critical framework-level functionality that most/all
other trailpacks will depend on, such as core
and router.

`js
const SystemTrailpack = require('trailpack/system')

module.exports = class HapiTrailpack extends SystemTrailpack {

}
`

#### server
These allow you to use various node.js web server frameworks with Trails, such
as express,
hapi,
and koa. Typically, only one
server pack will be installed in a Trails Application.


`js
const ServerTrailpack = require('trailpack/server')

module.exports = class HapiTrailpack extends ServerTrailpack {

}
`

#### datastore
Datastore trailpacks provide a unified way to configure various persistence
stores. These may be ORMs, query builders, or database drivers. Examples include
knex, graphql
and waterline. Typically,
only one datastore pack will be installed in a Trails Application.


`js
const DatastoreTrailpack = require('trailpack/datastore')

module.exports = class KnexTrailpack extends DatastoreTrailpack {

}
`

#### tool
Every application needs a suite of tools for development, debugging,
monitoring, etc. These trailpacks integrate various modules with Trails
to provide a richer developer experience. Some tool packs include
autoreload, webpack,
repl. Trails Application logic
will typically not rely on these trailpacks directly.


`js
const ToolTrailpack = require('trailpack/tool')

module.exports = class WebpackTrailpack extends ToolTrailpack {

}
`

#### extension
Extension packs exist to augment, or extend, the functionality of other
trailpacks or existing framework logic.
For example, footprints
provides a standard interface between server and datastore trailpacks.
realtime adds additional
functionality to a server. sails
lets you plugin an entire sails project directly into a Trails Application.
bootstrap extends the Trails
boot process so that a custom method can be run during application startup.


`js
const ExtensionTrailpack = require('trailpack/extension')

module.exports = class FootprintsTrailpack extends ExtensionTrailpack {

}
`

#### misc
All trailpacks that don't fit previous types.


`js
const Trailpack = require('trailpack')

module.exports = class ExampleTrailpack extends Trailpack {

}
``

$3

- Trailpack Implementation Guide
- API Reference

Contributing

We love contributions! Please see our Contribution Guide
for more information.

License

MIT

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