Important: starcounter-include component was designed for Starcounter 2 family and no longer supported in Starcounter 3. There will be no further development or improvements.

<starcounter-include>

<starcounter-include> is a custom element that lets you load partial HTML views into your Starcounter page, it uses

• <imported-template> - You can take full control over loaded <script>s and <link rel="import">s. Thanks to HTML Imports - caching, script execution, etc. is completely native.

You can use Shadow DOM v1 features to apply Document Fragment with custom HTML composition and slots to tune the presentation of HTML Elements given by the partial HTML view. It lets you blend and apply your desired look & feel to elements given by your and even other apps - which were mixed due to Starcounter mappings.

For more details see articles:

• "HTML partials/includes WebComponents-way" - How partials work,
• "Unobtrusive styling and composing 3rd party HTML content" - How to style them with Shadow DOM,
• "Layout compositions for HTML partials" - How to use styles in Starcounter

Kinds of compositions

<starcounter-include> recognizes 4 kinds of HTML compositions:

• Fallback composition - a single <style>:host{display: block;}</style><slot></slot> to display all things from light DOM in case no composition was provided
• Default composition - composition (or multiple concatenated compositions) found in the partial HTML view (<template is="declarative-shadow-dom"> part)
• Parent composition - composition found in the parent HTML view (content of <starcounter-include ...><template is="declarative-shadow-dom" presentation="parent">). It's used to enforce by parent view a given composition for any kind of elements.
• Custom composition - stored composition provided in JSON by BlendingProvider
• Temporary composition - explicit composition set directly in the shadow root of starcounter-include (for example by Chrome DevTools or <starcounter-layout-html-editor> in BlendingEditor)

Small sample

If you have /app/sub/page/path.html:

<template><h1>Hello {{username}}</h1></template>

and merged/blended JSON view-model

SubPageViewModel={App: {username: "World"Html: "/app/sub/page/path.html"}}

You can put it on screen with

<starcounter-includeview-model="{{ SubPageViewModel }}"></starcounter-include>

To produce

<h1>Hello World</h1>

Related custom elements

• <starcounter-layout-html-editor> - editor for Document Fragments

Features

• Applies two-way databinding, even for nested asynchronously loaded <polymer-element>s,
• Multiple (concatenated) templates per partial HTML view,
• Polymer's <template> features (binding, repeat, if, etc.),
• HTML Imports features:
• Sends request for template only once (HTML Import's caching),
• Supports <script>, <link>, <style> tags to be executed once,
• Supports <script>, <style> tags per template instance,
• Easy way to attach presentation expressed in declarative Shadow DOM,
• Blocks rendering of Shadow DOM until <link rel="stylesheet">s are loaded, unless loaded asynchronously (see below).

High-level docs

You can read more on Blendable Web Apps in Starcounter docs

• https://docs.starcounter.io/guides/blendable-web-apps/html-views
• https://docs.starcounter.io/guides/blendable-web-apps/view-composing

Partial HTML views limitations

• It should be W3C compliant Document body,
• It should contain at least one <template> tag in root node.

Partial JSON view-model conventions

• View-model contains Html property with path to file (:construction:, or just inline markup).

Install

Starcounter has it already pre-installed, under /sys/starcounter-include/starcounter-include.html, but if you want to use it separately as well.

Install the component using Bower:

$ bower install starcounter-include --save

Or download as ZIP.

Usage

1. Import Web Components' polyfill (if needed):

   <scriptsrc="bower_components/webcomponentsjs/webcomponents-lite.js"></script>

2. Import Custom Element:

   <linkrel="import" href="bower_components/starcounter-include/starcounter-include.html">

3. Start using it!

   <starcounter-includeview-model="{{ViewModel}}"></starcounter-include>

   or without mustache-style data-binding:

   document.querySelector("starcounter-include").viewModel=ViewModel;

   or with inline JSON:

   <starcounter-includeview-model="{&quot;Html&quot;: &quot;/path/to/file.html&quot;, &quot;some&quot;: &quot;data&quot;}"></starcounter-include>

Attributes

Attribute	Options	Default	Description
partial	JSON		Set to provide partial JSON view-model. It's also a partial property.
partial-id	String		Read-only attribute that represents PartialID fetched from partial JSON. It's also a partialId property.
view-model	JSON		Alias for partial
composition	String		Read-only attribute that reflects currently used composition kind

Properties

Property	Options	Default	Description
partial	Object		Object containing partial JSON view-model, bindable with Polymer
partialId	String		Partial Id used to identify partial, usually it's fetched from partial.{compositionProvider}.PartialId.
viewModel	Object		Alias for partial
compositionProvider	String	CompositionProvider_0	Key/app name of composition provider. could be overwritten per instance scInclude.compositionProvider or globally by changing the prototype, like: customElements.get('starcounter-include').prototype.compositionProvider = 'CustomProvider_7'

Events

Name	Detail	Description
starcounter-include-composition-saved	String stored composition	Triggered once composition is saved
partial-changed	Object{value: storedComposition, path: 'partial.{compositionProvider}.Composition'}	Polymer notification protocol compliant event to notify about partial.{compositionProvider}.Composition change, triggered once composition is saved.
view-model-changed	Object{value: storedComposition, path: 'viewModel.{compositionProvider}.Composition'}	Polymer notification protocol compliant event to notify about partial.{compositionProvider}.Composition change, triggered once composition is saved.
presentation-loaded	none	When all links from a stamped presentation finished loading (with success or failure).

Render-blocking links

To mimic native behavior of markup for Declarative Shadow DOM and to avoid FOUC the element will "block rendering" until all <link rel="stylesheet">s are loaded or throw an error.

You can opt-out by using the same technique you can use to asynchronously load the stylesheet into a static document:

<linkrel="preload" href="/path/to/styles.css" as="style" onload="this.rel='stylesheet'">

The blocked rendering is achieved by setting visibility: hidden on shadow host - <strcounter-include> element.

Test suite

• start mock server and simple dev static files server npm run serve
• open local browser at 127.0.0.1:8081/components/starcounter-include/test/

Caveats

ShadyCSS

In browsers with Shadow DOM polyfilled using ShadyDOM and ShadyCSS, styles may still leak. This seems to be related to the limitation in the polyfill and its API.

• it does not cover Vanilla JS custom elements automatically and API does not provide sufficient methods to cover our case,
• shadow roots provided without template (compositions from DB) and different for every instance of the element seems not to be covered by polyfill at all,
• style scoping methods that transform HTML markup seems to be broken when element is being upgraded. ShadyCSS is going to be refactored soon, so we prefer to wait with heavy workarounds.

Please prepare your selectors more carefully. Feel free to report issues with your specific use-cases. We will try to provide a solution that works now, and make sure we will eventually cover them in a nice way.

Contributing and Development

History

For detailed changelog, check Releases.

License

MIT