Getting Started with SPAs in AEM - Angular getting-started-with-spas-in-aem-angular

Single page applications (SPAs) can offer compelling experiences for website users. Developers want to be able to build sites using SPA frameworks and authors want to seamlessly edit content within AEM for a site built using SPA frameworks.

The SPA authoring feature offers a comprehensive solution for supporting SPAs within AEM. This article presents a simplified SPA application on the Angular framework, explains how it is put together, allowing you to get up-and-running with your own SPA quickly.

Introduction introduction

This article summarizes the basic functioning of a simple SPA and the minimum that you need to know to get yours running.

For more detail on how SPAs work in AEM, see the following documents:

This document will walk through the structure of a simplified SPA and illustrate how it works so you can apply this understanding to your own SPA.

Dependencies, Configuration, and Building dependencies-configuration-and-building

In addition to the expected Angular dependency, the sample SPA can leverage additional libraries to make the creation of the SPA more efficient.

Dependencies dependencies

The package.json file defines the requirements of the overall SPA package. The minimum required AEM dependencies are listed here.

"dependencies": {
  "@adobe/aem-angular-editable-components": "~1.0.3",
  "@adobe/aem-spa-component-mapping": "~1.0.5",
  "@adobe/aem-spa-page-model-manager": "~1.0.3"
}

The aem-clientlib-generator is leveraged to make the creation of client libraries automatic as part of the build process.

"aem-clientlib-generator": "^1.4.1",

Further details about it can be found on GitHub here.

The aem-clientlib-generator is configured in the clientlib.config.js file as follows.

module.exports = {
    // default working directory (can be changed per 'cwd' in every asset option)
    context: __dirname,

    // path to the clientlib root folder (output)
    clientLibRoot: "./../content/jcr_root/apps/my-angular-app/clientlibs",

    libs: {
        name: "my-angular-app",
        allowProxy: true,
        categories: ["my-angular-app"],
        embed: ["my-angular-app.responsivegrid"],
        jsProcessor: ["min:gcc"],
        serializationFormat: "xml",
        assets: {
            js: [
                "dist/**/*.js"
            ],
            css: [
                "dist/**/*.css"
            ]
        }
    }
};

Building building

Actually building the app leverages Webpack for transpilation in addition to the aem-clientlib-generator for automatic client library creation. Therefore the build command will resemble:

"build": "ng build --build-optimizer=false && clientlib",

Once built, the package can be uploaded to an AEM instance.

AEM Project Archetype aem-project-archetype

Any AEM project should leverage the AEM Project Archetype, which supports SPA projects using React or Angular and leverages the SPA SDK.

Application Structure application-structure

Including the dependencies and building your app as described previously will leave you with a working SPA package which you can upload to your AEM instance.

The next section of this document will take you through how an SPA in AEM is structured, the important files which drive the application, and how they work together.

A simplified image component is used as an example, but all components of the application are based on the same concept.

app.module.ts app-module-ts

The entry point into the SPA is the app.module.ts file shown here simplified to focus on the important content.

// app.module.ts
import { BrowserModule, BrowserTransferStateModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
import { SpaAngularEditableComponentsModule } from '@adobe/aem-angular-editable-components';
import { AppRoutingModule } from './app-routing.module';

@NgModule({
  imports: [ BrowserModule.withServerTransition({ appId: 'my-angular-app' }),
    SpaAngularEditableComponentsModule,
    AppRoutingModule,
    BrowserTransferStateModule ],
  providers: ...,
  declarations: [ ... ],
  entryComponents: [ ... ],
  bootstrap: [ AppComponent ]
})
export class AppModule {}

The app.module.ts file is the starting point of the app and contains the initial project configuration and uses AppComponent to bootstrap the App.

Static Instantiation static-instantiation

When the component is instantiated statically using the component template, the value must be passed from the model to the properties of the component. The values from the model are passed as attributes to be later available as component properties.

app.component.ts app-component-ts

Once app.module.ts bootstraps AppComponent, it can then initialize the App, which is shown here in a simplified version to focus on the important content.

// app.component.ts
import { Component } from '@angular/core';
import { ModelManager } from '@adobe/aem-spa-page-model-manager';
import { Constants } from "@adobe/aem-angular-editable-components";

@Component({
  selector: 'app-root',
  template: `
    <router-outlet></router-outlet>
  `
})

export class AppComponent {
  items;
  itemsOrder;
  path;

  constructor() {
    ModelManager.initialize().then(this.updateData.bind(this));
  }

  private updateData(model) {
    this.path = model[Constants.PATH_PROP];
    this.items = model[Constants.ITEMS_PROP];
    this.itemsOrder = model[Constants.ITEMS_ORDER_PROP];
  }
}

main-content.component.ts main-content-component-ts

By processing the page, app.component.ts calls main-content.component.ts listed here in a simplified version.

import { Component } from '@angular/core';
import { ModelManagerService }     from '../model-manager.service';
import { ActivatedRoute } from '@angular/router';
import { Constants } from "@adobe/aem-angular-editable-components";

@Component({
  selector: 'app-main',
  template: `
    <aem-page class="structure-page" [attr.data-cq-page-path]="path" [cqPath]="path" [cqItems]="items" [cqItemsOrder]="itemsOrder" ></aem-page>
  `
})

export class MainContentComponent {
  items;
  itemsOrder;
  path;

  constructor( private route: ActivatedRoute,
    private modelManagerService: ModelManagerService) {
    this.modelManagerService.getData({ path: this.route.snapshot.data.path }).then((data) => {
      this.path = data[Constants.PATH_PROP];
      this.items = data[Constants.ITEMS_PROP];
      this.itemsOrder = data[Constants.ITEMS_ORDER_PROP];
    });
  }
}

The MainComponent ingests the JSON representation of the page model and processes the content to wrap/decorate each element of the page. Further details on the Page can be found in the document SPA Blueprint.

image.component.ts image-component-ts

The Page is composed of components. With the JSON ingested, the Page can process those components such as image.component.ts as shown here.

/// image.component.ts
import { Component, Input } from '@angular/core';

const ImageEditConfig = {

    emptyLabel: 'Image',

    isEmpty: function(cqModel) {
        return !cqModel || !cqModel.src || cqModel.src.trim().length < 1;
    }
};

@Component({
  selector: 'app-image',
  templateUrl: './image.component.html',
})

export class ImageComponent {
  @Input() src: string;
  @Input() alt: string;
  @Input() title: string;
}

MapTo('my-angular-app/components/image')(ImageComponent, ImageEditConfig);

The central idea of SPAs in AEM is the idea of mapping SPA components to AEM components and updating the component when the content is modified (and vice versa). See the document SPA Editor Overview for an summary of this communication model.

MapTo('my-angular-app/components/image')(Image, ImageEditConfig);

The MapTo method maps the SPA component to the AEM component. It supports the use of a single string or an array of strings.

ImageEditConfig is a configuration object that contributes to enabling the authoring capabilities of a component by providing the necessary metadata for the editor to generate placeholders

If there is no content, labels are provided as placeholders to represent the empty content.

Dynamically Passed Properties dynamically-passed-properties

The data coming from the model are dynamically passed as properties of the component.

image.component.html image-component-html

Finally the image can be rendered in image.component.html.

// image.component.html
<img [src]="src" [alt]="alt" [title]="title"/>

Sharing Information Between SPA Components sharing-information-between-spa-components

It is regularly necessary for components within a single-page application to share information. There are several recommended ways of doing this, listed as follows in increasing order of complexity.

Next Steps next-steps

For a step-by-step guide to creating your own SPA, see the Getting Started with the AEM SPA Editor - WKND Events Tutorial.

For further information about how to oraganize yourself to develop SPAs for AEM see the article Developing SPAs for AEM.

For further details about the dynamic model to component mapping and how it works within SPAs in AEM, see the article Dynamic Model to Component Mapping for SPAs.

If you wish to implement SPAs in AEM for a framework other than React or Angular or simply wish to take a deep dive into how the SPA SDK for AEM works, refer to the SPA Blueprint article.