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A library for creating reusable Embedded Fantom (efan) components
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readme.md

efanXtra v2.0.2


Written in: Fantom pod: v2.0.2 Licence: ISC

Overview

efanXtra creates managed libraries of reusable Embedded Fantom (efan) components. Influenced by Java's Tapestry 5, it pairs up Fantom classes and efan template files to encapsulate model / view behaviour.

efanXtra extends efan, is powered by IoC and works great with Slim templates.

efanXtra excels in a BedSheet web environment, where URLs are automatically mapped to efan components (see Pillow), but is presented here context free for maximum reuse. Think email, code generation, blog posts, etc...

Install

Install efanXtra with the Fantom Pod Manager ( FPM ):

C:\> fpm install afEfanXtra

Or install efanXtra with fanr:

C:\> fanr install -r http://eggbox.fantomfactory.org/fanr/ afEfanXtra

To use in a Fantom project, add a dependency to build.fan:

depends = ["sys 1.0", ..., "afEfanXtra 2.0"]

Documentation

Full API & fandocs are available on the Eggbox - the Fantom Pod Repository.

Quick Start

  1. Create a text file called Overdue.efan Dear <%= userName %>,

    It appears the following rented DVDs are overdue:

     <%= dvds.join(", ") %>
    

    Please return them at your convenience.

    <%= app.renderSignOff("The Management") %>

  2. Create a text file called Overdue.fan using afIoc using afEfanXtra

    class Overdue : EfanComponent {

     // use afIoc services!
     @Inject
     DvdService? dvdService
    
     // fields can be accessed by the template
     Str? userName
    
     // standard it-block ctor for ioc injection
     new make(|This| f) { f(this) }
    
     // use lifecycle methods to initialise your components
     @InitRender
     Void initRender(Str userName) {
         this.userName = userName
     }
    
     // mixin methods can be called from the template
     Str[] dvds() {
         dvdService.findByName(userName)
     }
    

    }

  3. Create a text file called AppModule.fan using afIoc

    const class AppModule {

     Void defineServices(RegistryBuilder defs) {
         defs.addService(DvdService#)
     }
    
     @Contribute { serviceType=EfanLibraries# }
     Void contributeEfanLibs(Configuration config) {
    
         // contribute all components in the pod as a library named 'app'
         config["app"] = AppModule#.pod
     }
    

    }

  4. Then to render an efan component: efanXtra.component(Overdue#).render(["Mr Smith"])

Full example source code available on BitBucket.

Components

An efan component consists of a Fantom class (or mixin) that extends EfanComponent and a corresponding efan template file.

efanXtra does away with efan's ctx variable and instead lets the template access fields and methods of the component class directly.

Classes

Component classes extend the EfanComponent mixin and may or may not be const.

efanXtra caches component instances where it can, so it may be advantageous to use const classes, espically if using a lot of IoC injection. const services may be injected as usual, and abstract render variables may be used for state.

Taking the Overdue component as an example:

using afEfanXtra

const class Overdue : EfanComponent {

    // standard service injection
    @Inject
    const DvdService? dvdService

    // render variables are mutable
    abstract Str? userName

    // standard it-block ctor for ioc injection
    new make(|This| f) { f(this) }

    // use lifecycle methods to initialise your components
    @InitRender
    Void initRender(Str userName) {
        this.userName = userName
    }

    // mixin methods can be called from the template
    Str[] dvds() {
        dvdService.findByName(userName)
    }
}

Mixins

Component mixins extend the EfanComponent mixin and may or may not be const.

All fields and methods of the mixin are visible and directly accessible in the efan template. Fields, as per standard mixin contracts, must be abstract.

Components are created by IoC so feel free to annotate fields with @Inject just as you would with a service class.

See Lifecycle Methods to see how to initialise and pass data into your components.

Templates

By default, efan template files have the same name as the class, but with an .efan extension. If you wish the template to have a different name to the Fantom class, you can set an explicit URL with the @TemplateLocation facet. Example:

@TemplateLocation { url=`fan://acmePod/templates/Notice.efan` }
class Overdue : EfanComponent {
    ...
}

Note if you have a type hierarchy, and a template for the subclass isn't found, then templates are searched again but using the base class name.

Pod Templates

A template may be a pod resource. For example, if you were to create a component called Layout, you may have the following files:

/fan/components/Layout.fan  --> the mixin class
/res/components/Layout.efan --> the template file

For efanXtra to find the template file, be sure to add /res/components/ as a resDir in your build.fan.

resDirs = [`res/components/`]

ALIEN-AID: Note resource directories in build.fan are NOT nested. Adding res/ will NOT add res/components/.

File System Templates

Templates may also be kept on the file system. This can be very handy for development, as templates on the file system don't require the pod to be re-built (or the application re-started) when they change.

To do this, contribute to TemplateDirectories to tell efanXtra where to look for templates:

const class AppModule {

    @Contribute { serviceType=TemplateDirectories# }
    Void contributeTemplateDirs(Configuration config) {
        config.add(`etc/components/`)
    }
}

Note that like Fantom resource directories, template directories are NOT nested; adding etc/ will NOT add etc/components/.

Also note that the directory URIs must end in a slash.

File system template are checked every 2min in production and every 2sec in development. To change these timings, add the following configuration:

@Contribute { serviceType=ApplicationDefaults# }
Void configureAppDefaults(Configuration config) {
    config["afEfanXtra.templateTimeout"] = 1min
}

Fandoc Comment Templates

Templates may also be embedded in the fandoc comment of the component! Simply prefix the fandoc comment with template: followed by the type. Example:

using afEfanXtra

** template: efan
**
** Yo Dawg! Check <%= hello %>
**
class TemplateFromFandocComment : EfanComponent {
    Str hello() { "this out!" }
}

Will render Yo Dawg! Check this out!

Or, if you want to embed the template inside the fandoc comment, use a <pre> tag:

using afEfanXtra

** This is not rendered.
**
** pre>
** template: efan
**
** Yo Digidy! Check <%= hello %>
** <pre
**
** Nor is this.
class TemplateFromFandocComment : EfanComponent {
    Str hello() { "this out!" }
}

Which will render Yo Digidy! Check this out!

This is useful for keeping everything together in small components where you don't want the inconvenience of an external template file.

Libraries

Components are organised by libraries. A library encompasses all components within a pod. To use your efan components effectively, you should add your application pod as a library. Do this in your AppModule:

using afIoc
using afEfanXtra

const class AppModule {

    @Contribute { serviceType=EfanLibraries# }
    Void contributeEfanLibs(Configuration config) {

        // contribute all components in this pod as a library called 'app'
        config["app"] = AppModule#.pod
    }
}

Library classes are automatically injected as fields into your components. Library classes contain component render methods. In the Quick Start Example, the library (in a field named app) would bave 2 render methods, available for use in your templates:

app.renderOverdue(Str userName)
app.renderSignOff(Str who)

This allows you to render components from within templates by calling <libName>.render<ComponentName>(...). Example:

<%= app.renderSignOff("The Management") %>

ALIEN-AID: Library render methods are logged at registry startup so you don't have to remember the method signatures!

Lifecycle Methods

Components can be thought of as having a lifecycle for the duration of their render. Components can be made aware of the lifecycle by annotating callback methods with lifecycle facets. The lifecycle, and all state held in the component, only exists for the duration of the render.

efanXtra Component Lifecycle

@InitRender

A method annotated with @InitRender will be called before any other. It allows you to initialise and prepare your component for rendering.

The @InitRender method may take any arguments, the signature will be mimicked by the containing library's render method. Example, if your @InitRender looks like:

class MyComponent : EfanComponent {

    @InitRender
    Void initRender(Int x, Str y) { ... }
}

then the library render method will look like:

Obj? renderMyComponent(Int x, Str y, |->| bodyFunc := null) { ... }

This lets you pass any arguments you want into your components.

@InitRender methods may return Bool. If true, the template is rendered as usual. If false, then template rendering is skipped.

@BeforeRender

A method annotated with @BeforeRender is invoked after @InitRender but before any template rendering. It may optionally take a StrBuf as a parameter, this will hold the contents of the current render buffer.

@BeforeRender methods may return Bool. If true, the template is rendered as usual. If false, then template rendering is skipped.

@AfterRender

A method annotated with @AfterRender is invoked after the template has rendered. It may optionally take a StrBuf as a parameter, this will hold the contents of the current render buffer.

@AfterRender methods may return Bool. If true, the template rendering ends. If false, template rendering is sent back to @BeforeRender. In this way, simple loops may be set up.

Render Variables

Efan components can store state! Components may be const and they may be mixins, but they can still store variables that can be accessed and used by the rendering template. Taking the Overdue component as an example:

using afEfanXtra

const mixin Overdue : EfanComponent {

    // render variables may also be injected
    @Inject
    abstract DvdService? dvdService

    abstract Str? userName

    @InitRender
    Void initRender(Str userName) {
        this.userName = userName
    }
}

userName is a render variable used by the efan template. Before initRender() is called, all render variables are reset to null (hence they need to be nullable). They may then be initialised during initRender(), and used and / or reset at any other point in the rendering lifecycle.

Note that state is not preserved between different renderings of the component.

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