Visual SPA Editor

What it does

The Visual SPA Editor connects the modern component-architecture of SPA, with the component concept of CMS page editors. You can build an SPA, and give it placeholder areas, that can be managed from a CMS.

  • Frontend Developer: Builds SPA. Adapts SPA to make it content manageable.

  • Frontend or Magnolia Developer: Creates Magnolia bindings and dialogs. (Putting handles and knobs on the components for authors.)

  • Content authors and marketers: Choose which components to put in the areas, in what order, and edit their contents.

SPA block 1024x512

Overview

Authors use Page Editor:

  • Can build experiences based on predefined page and component templates.

  • Result is a hierarchy of pages and components stored in Magnolia.

Implementation:

  • Small javascript library for each JS framework (React, Angular, soon Vue)

  • JS library provides the Area component. This is a placeholder for authors.

  • A Magnolia REST endpoint serves both layout and content for each page.

  • JS library uses this information to dynamically build app. It instantiates frontend components and passes the content in as props.

  • In the authoring experience, another Magnolia REST endpoint serves information about all the templates on the page. For example it provides which components are available in an area.

Capabilities:

  • Use any frontend component (React, Angular, Vue) without modification. They get all CMS content passed in as props.

  • Supports nested components.

  • Supports multiple and nested pages (that is a page tree).

  • Authoring feature even works if the DOM changes dynamically while authoring.

Two key usage scenarios:

  • Existing SPA: Add content management to an Existing SPA

  • New DX/CMS project: team wants to use React templating.

Differences to Basic Headless

basic headless vs next level 1280

In Basic Headless, an author fills out a form, in a separate tool. Content is stored in a list in a database, and it is retrieved as a list via a REST API request. The typical frontend loops through the list and renders each item in a region of the view. So, authors can manage content items. YAY. But they cannot manage experiences.

With the SPA editor, an author chooses and places components on a visual page. For each component they fill out a form, in context. Content is stored in a tree in a database, we could call it a leaf, and it’s retrieved as a tree via a REST API

The tree is important - the location of the leaf in the tree represents where the component was placed in the page. Each leaf also stores which type of component it is. In the frontend the code follows every branch of the content tree, and for each leaf it displays the type of component specified in the leaf.

The result: It’s a tool an author can use to manage content & to build out the full experience.

How it works in Production

The web experience is a SPA, served from any server.

It hits a Magnolia REST Delivery endpoint to get a JSON page payload which includes:

  • Content: The contents of all of the components on one page. (Typically a delivery endpoint)

  • Layout: The layout of components in the page (Actually, just the heirarchy of the content nodes.)

Mapping Information: which SPA component to instantiate for each Magnolia component, is in a file in the SPA.

The SPA instantiates 1) the specified components, with 2) that content, in 3) that heirarchy.

When the user navigates to a new Route (aka Page), the SPA hits the endpoint again and refreshes its content.

How it works in Editing Experience

An Author opens a page in the Magnolia Pages App. The template has renderType: spa.

Page Editor loads the SPA which is bundled in a Magnolia module.

It hits a Magnolia REST Delivery endpoint as above.

It hits the templateDefinition Magnolia REST endpoint for information about all the templates on the page. For example it provides which components are available in an area.

The JS library instantiates the components as above, but additionally adds hints/annotations for the Page Editor in the form of the HTML comments, for every area and component on the page. Then it calls the mgnlRefresh method to request the Edit Bars.

The Page Editor injects the green Edit Bars into the DOM, based on the annotations.

Author uses the Edit Bars.

Edits are persisted to Magnolia. The Page Editor reloads the page in the iframe.

Not seeing green bars while editing?

In some instances, you may not be seeing the green edit bars while using the Visual SPA editor. If this is the case, try some of the following techniques.

Tip Notes

1

iframe preview URL

Make sure your iframe preview URL in the Pages app is correct.

This should be the Author SPA with the correct path name and query parameters.

2

Correct environment

Make sure the Author SPA is fetching data from the correct environment, the Magnolia Author instance.

It should fetch both the pages data and template annotations for the correct page.

3

Correct libraries

Ensure you’re using the latest frontend libraries.

4

HTML DOM comments

Check to see if there are any HTML comments in the DOM.

  • See comments?

  • Don’t see comments?

Try running the window.mgnlFrameReady() function from inside the preview iframe to attempt to render the green bars. There could be a race condition[1] which essentially tries to render the bars before your site is ready.

If this is the case, manually call window.mgnlFrameReady():

function myFunction() {
  const element = document.querySelector('.mgnlEditorBar');

  if (element) {
    clearInterval(intervalId);
  } else {
    window.mgnlFrameReady();
  }
}

const intervalId = setInterval(myFunction, 200); (1)
1 Where the time delay (200) is in milliseconds.

The green bars are placed in the Page Editor based on the comments that the frontend places in the HTML using one of the frontend libraries. It is imperative to have the HTML comments rendered.

  • Make sure the SPA fetches template annotations properly. It could be that it’s unaware it’s in the authoring context.

  • Make sure the call that the SPA makes can be run in incognito mode in your browser. Potentially, some security settings are preventing SPA from fetching template annotations.

Check the console log

  1. In your code, go to where you fetch the template-annotations.

  2. Check the console log to ensure it’s working properly.

    if (I_AM_INSIDE_MAGNOLIA) { (1)
  console.log('Hooray, I am here.') (2)
  console.log('I am trying to fetch:', 'MAGNOLIA/.rest/template-annotations/v1' + PATH_TO_NODE) (2)
  const templateAnnotationsRes = await fetch(
    'MAGNOLIA/.rest/template-annotations/v1' + PATH_TO_NODE
  );
  ...
  console.log('RESPONSE', templateAnnotations)
}
    1 If the code runs successfully inside the if statement, then it is running in the correct context for the Pages app.
    2 Print something along these lines to ensure the console log outputs the statement. This checks the correct URL is being used and you’re fetching from the correct Magnolia instance and page.

    If the response is okay, you should get the mappings for your HTML comments.

1. A race condition is a situation when several processes or threads are attempting to access the same resource.

How to Make your SPA Editable

Check out the Hello Magnolia - SPA tutorial to really get hands-on.

Start by browsing the minimal-headless-spa-demos repository. There you can see a well organized, complete working example.

Step by step

Page

  1. Create a SPA component to represent your page. Use a prop, like title.

    link:/spa/react-minimal/src/pages/Basic.js

  2. Load the content from the delivery endpoint for the the current route.

    link:/spa/react-minimal/src/helpers/PageLoader.js

  3. Load the template information from the templateDefinition endpoint, based on the templateID of the route page.

    link:/spa/react-minimal/src/helpers/PageLoader.js

  4. Create a component mapping configuration.

    link:/spa/react-minimal/src/magnolia.config.js

  5. Use the Page component from the Magnolia JS library to instantiate a frontend component. based on the templateId of the magnolia page, and the mapping.

    link:/spa/react-minimal/src/helpers/PageLoader.js

  6. Deploy your SPA. Typically on its own server.

    You could optionally host your SPA in a Magnolia light module like so: /magnolia/light-modules/react-minimal-lm/webresources build.

  7. Create a Page Template definition and point it to the SPA URL. Add a dialog with a title property.

    link:/magnolia/light-modules/react-minimal-lm/templates/pages/basic.yaml

  8. Run the page app. Edit the title.

Area

  1. Add areas to page template definition to enable author managed components

  2. Add Area components for the same areas to the frontend page component.

Components

  1. Create frontend components as usual.

    link:/magnolia/light-modules/spa-lm/dialogs/components/headline.yaml

  2. Create Magnolia components for each frontend component. (Just a definition and dialog, no template script needed!) Dialog properties will be available in your frontend component as props.

    link:/magnolia/light-modules/spa-lm/templates/components/headline.yaml link:/magnolia/light-modules/spa-lm/dialogs/components/headline.yaml

  3. Add the component to your mapping configuration file.

  4. Repeat and prosper!

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