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Map SPA components to AEM components

Learn how to map Angular components to Adobe Experience Manager (AEM) components with the AEM SPA Editor JS SDK. Component mapping enables users to make dynamic updates to SPA components within the AEM SPA Editor, similar to traditional AEM authoring.
This chapter takes a deeper-dive into the AEM JSON model API and how the JSON content exposed by an AEM component can be automatically injected into a Angular component as props.

Objective

  1. Learn how to map AEM components to SPA Components.
  2. Understand the difference between Container components and Content components.
  3. Create a new Angular component that maps to an existing AEM component.

What you will build

This chapter will inspect how the provided Text SPA component is mapped to the AEM Text component. A new Image SPA component will be created that can be used in the SPA and authored in AEM. Out of the box features of the Layout Container and Template Editor policies will also be used to create a view that is a little more varied in appearance.

Prerequisites

Review the required tooling and instructions for setting up a local development environment .

Get the code

  1. Download the starting point for this tutorial via git:
    $ git clone git@github.com:adobe/aem-guides-wknd-spa.git
    $ cd aem-guides-wknd-spa
    $ git checkout Angular/map-components-start
    
    
  2. Deploy the code base to a local AEM instance using Maven:
    $ mvn clean install -PautoInstallSinglePackage
    
    
    If using AEM 6.x add the classic profile:
    $ mvn clean install -PautoInstallSinglePackage -Pclassic
    
    
You can always view the finished code on GitHub or check the code out locally by switching to the branch Angular/map-components-solution .

Mapping Approach

The basic concept is to map a SPA Component to an AEM Component. AEM components, run server-side, export content as part of the JSON model API. The JSON content is consumed by the SPA, running client-side in the browser. A 1:1 mapping between SPA components and an AEM component is created.
High-level overview of mapping an AEM Component to a Angular Component

Inspect the Text Component

The AEM Project Archetype provides a Text component that is mapped to the AEM Text component . This is an example of a content component, in that it renders content from AEM.
Let's see how the component works.

Inspect the JSON model

  1. Before jumping into the SPA code, it is important to understand the JSON model that AEM provides. Navigate to the Core Component Library and view the page for the Text component. The Core Component Library provides examples of all the AEM Core Components.
  2. Select the JSON tab for one of the examples:
    You should see three properties: text , richText , and :type .
    :type is a reserved property that lists the sling:resourceType (or path) of the AEM Component. The value of :type is what is used to map the AEM component to the SPA component.
    text and richText are additional properties that will be exposed to the SPA component.

Inspect the Text component

  1. Open a new terminal and navigate to the ui.frontend folder inside the project. Run npm install and then npm start to start the webpack dev server :
    $ cd ui.frontend
    $ npm run start:mock
    
    
    The ui.frontend module is currently set up to use the mock JSON model .
  2. You should see a new browser window open to http://localhost:4200/content/wknd-spa-angular/us/en/home.html
  3. In the IDE of your choice open up the AEM Project for the WKND SPA. Expand the ui.frontend module and open the file text.component.ts under ui.frontend/src/app/components/text/text.component.ts :
  4. The first area to inspect is the class TextComponent at ~line 35:
    export class TextComponent {
        @Input() richText: boolean;
        @Input() text: string;
        @Input() itemName: string;
    
        @HostBinding('innerHtml') get content() {
            return this.richText
            ? this.sanitizer.bypassSecurityTrustHtml(this.text)
            : this.text;
        }
        @HostBinding('attr.data-rte-editelement') editAttribute = true;
    
        constructor(private sanitizer: DomSanitizer) {}
    }
    
    
    @Input() decorator is used to declare fields who's values are set via the mapped JSON object, reviewed earlier.
    @HostBinding('innerHtml') get content() is a method that exposes the authored text content from the value of this.text . In the case that the content is rich text (determined by the this.richText flag) Angular's built-in security is bypassed. Angular's DomSanitizer is used to "scrub" the raw HTML and prevent Cross Site Scripting vulnerabilities. The method is bound to the innerHtml property using the @HostBinding decorator.
  5. Next inspect the TextEditConfig at ~line 24:
    const TextEditConfig = {
        emptyLabel: 'Text',
        isEmpty: cqModel =>
            !cqModel || !cqModel.text || cqModel.text.trim().length < 1
    };
    
    
    The above code is responsible for determining when to render the placeholder in the AEM author environment. If the isEmpty method returns true then the placeholder will be rendered.
  6. Finally take a look at the MapTo call at ~line 53:
    MapTo('wknd-spa-angular/components/text')(TextComponent, TextEditConfig );
    
    
    MapTo is provided by the AEM SPA Editor JS SDK ( @adobe/cq-angular-editable-components ). The path wknd-spa-angular/components/text represents the sling:resourceType of the AEM component. This path gets matched with the :type exposed by the JSON model observed earlier. MapTo parses the JSON Model response and passes the correct values to the @Input() variables of the SPA component.
    You can find the AEM Text component definition at ui.apps/src/main/content/jcr_root/apps/wknd-spa-angular/components/text .
  7. Experiment by modifying the en.model.json file at ui.frontend/src/mocks/json/en.model.json .
    At ~line 62 update the first Text value to use an H1 and u tags:
        "text": {
            "text": "<h1><u>Hello World!</u></h1>",
            "richText": true,
            ":type": "wknd-spa-angular/components/text"
        }
    
    
    Return to the browser to see the effects served by the webpack dev server :
    Try toggling the richText property between true / false to see the render logic in action.
  8. Inspect text.component.html at ui.frontend/src/app/components/text/text.component.html .
    This file is empty since the entire contents of the component will be set by the innerHTML property.
  9. Inspect the app.module.ts at ui.frontend/src/app/app.module.ts .
    @NgModule({
    imports: [
        BrowserModule,
        SpaAngularEditableComponentsModule,
        AppRoutingModule
    ],
    providers: [ModelManagerService, { provide: APP_BASE_HREF, useValue: '/' }],
    declarations: [AppComponent, TextComponent, PageComponent, HeaderComponent],
    entryComponents: [TextComponent, PageComponent],
    bootstrap: [AppComponent]
    })
    export class AppModule {}
    
    
    The TextComponent is not explicitly included, but rather dynamically via AEMResponsiveGridComponent provided by the AEM SPA Editor JS SDK. Therefore must be listed in the app.module.ts ' entryComponents array.

Create the Image Component

Next, create an Image Angular component that is mapped to the AEM Image component . The Image component is another example of a content component.

Inspect the JSON

Before jumping into the SPA code, inspect the JSON model provided by AEM.
  1. Properties of src , alt , and title will be used to populate the SPA Image component.
    There are other Image properties exposed ( lazyEnabled , widths ) that allow a developer to create an adaptive and lazy-loading component. The component built in this tutorial will be simple and will not use these advanced properties.
  2. Return to your IDE and open up the en.model.json at ui.frontend/src/mocks/json/en.model.json . Since this is a net-new component for our project we need to "mock" the Image JSON.
    At ~line 70 add a JSON entry for the image model (don't forget about the trailing comma , after the second text_386303036 ) and update the :itemsOrder array.
    ...
    ":items": {
                ...
                "text_386303036": {
                    "text": "<p>A new text component.</p>\r\n",
                    "richText": true,
                    ":type": "wknd-spa-angular/components/text"
                    },
                "image": {
                    "alt": "Rock Climber in New Zealand",
                    "title": "Rock Climber in New Zealand",
                    "src": "/mocks/images/adobestock-140634652.jpeg",
                    ":type": "wknd-spa-angular/components/image"
                }
            },
            ":itemsOrder": [
                "text",
                "text_386303036",
                "image"
            ],
    
    
    The project includes a sample image at /mock-content/adobestock-140634652.jpeg that will be used with the webpack dev server .
    You can view the full en.model.json here .
  3. Add a stock photo to be displayed by the component.
    Create a new folder named images beneath ui.frontend/src/mocks . Download adobestock-140634652.jpeg and place it in the newly created images folder. Feel free to use your own image, if desired.

Implement the Image component

  1. Stop the webpack dev server if started.
  2. Create a new Image component by running the Angular CLI ng generate component command from within ui.frontend folder:
    $ ng generate component components/image
    
    
  3. In the IDE, open image.component.ts at ui.frontend/src/app/components/image/image.component.ts and update as follows:
    import {Component, Input, OnInit} from '@angular/core';
    import {MapTo} from '@adobe/cq-angular-editable-components';
    
    const ImageEditConfig = {
    emptyLabel: 'Image',
    isEmpty: cqModel =>
        !cqModel || !cqModel.src || cqModel.src.trim().length < 1
    };
    
    @Component({
    selector: 'app-image',
    templateUrl: './image.component.html',
    styleUrls: ['./image.component.scss']
    })
    export class ImageComponent implements OnInit {
    
    @Input() src: string;
    @Input() alt: string;
    @Input() title: string;
    
    constructor() { }
    
    get hasImage() {
        return this.src && this.src.trim().length > 0;
    }
    
    ngOnInit() { }
    }
    
    MapTo('wknd-spa-angular/components/image')(ImageComponent, ImageEditConfig);
    
    
    ImageEditConfig is the configuration to determine whether to render the author placeholder in AEM, based on if the src property is populated.
    @Input() of src , alt , and title are the properties mapped from the JSON API.
    hasImage() is a method that will determine if the image should be rendered.
    MapTo maps the SPA component to the AEM component located at ui.apps/src/main/content/jcr_root/apps/wknd-spa-angular/components/image .
  4. Open image.component.html and update it as follows:
    <ng-container *ngIf="hasImage">
        <img class="image" [src]="src" [alt]="alt" [title]="title"/>
    </ng-container>
    
    
    This will render the <img> element if hasImage returns true .
  5. Open image.component.scss and update it as follows:
    :host-context {
        display: block;
    }
    
    .image {
        margin: 1rem 0;
        width: 100%;
        border: 0;
    }
    
    
    The :host-context rule is critical for the AEM SPA editor placeholder to function correctly. All SPA components that are intended to be authored in the AEM page editor will need this rule at a minimum.
  6. Open app.module.ts and add the ImageComponent to the entryComponents array:
    entryComponents: [TextComponent, PageComponent, ImageComponent],
    
    
    Like the TextComponent , the ImageComponent is dynamically loaded, and must be included in the entryComponents array.
  7. Start the webpack dev server to see the ImageComponent render.
    $ npm run start:mock
    
    
    Image added to the SPA
    Bonus challenge : Implement a new method to display the value of title as a caption beneath the image.

Update Policies in AEM

The ImageComponent component is only visible in the webpack dev server . Next, deploy the updated SPA to AEM and update the template policies.
  1. Stop the webpack dev server and from the root of the project, deploy the changes to AEM using your Maven skills:
    $ cd aem-guides-wknd-spa
    $ mvn clean install -PautoInstallSinglePackage
    
    
  2. From the AEM Start screen navigate to Tools > Templates > WKND SPA Angular .
    Select and edit the SPA Page :
  3. Select the Layout Container and click it's policy icon to edit the policy:
  4. Under Allowed Components > WKND SPA Angular - Content > check the Image component:
    Under Default Components > Add mapping and choose the Image - WKND SPA Angular - Content component:
    Enter a mime type of image/* .
    Click Done to save the policy updates.
  5. In the Layout Container click the policy icon for the Text component:
    Create a new policy named WKND SPA Text . Under Plugins > Formatting > check all the boxes to enable additional formatting options:
    Under Plugins > Paragraph Styles > check the box to Enable paragraph styles :
    Click Done to save the policy update.
  6. You should also be able to edit the Text component and add additional paragraph styles in full-screen mode.
  7. You should also be able to drag+drop an image from the Asset finder :
  8. Add your own images via AEM Assets or install the finished code base for the standard WKND reference site . The WKND reference site includes many images that can be re-used on the WKND SPA. The package can be installed using AEM's Package Manager .

Inspect the Layout Container

Support for the Layout Container is automatically provided by the AEM SPA Editor SDK. The Layout Container , as indicated by the name, is a container component. Container components are components that accept JSON structures which represent other components and dynamically instantiate them.
Let's inspect the Layout Container further.
  1. In the IDE open responsive-grid.component.ts at ui.frontend/src/app/components/responsive-grid :
    import { AEMResponsiveGridComponent,MapTo } from '@adobe/cq-angular-editable-components';
    
    MapTo('wcm/foundation/components/responsivegrid')(AEMResponsiveGridComponent);
    
    
    The AEMResponsiveGridComponent is implemented as part of the AEM SPA Editor SDK and is included in the project via import-components .
  2. The Layout Container component has a sling:resourceType of wcm/foundation/components/responsivegrid and is recognized by the SPA Editor using the :type property, just like the Text and Image components.
    The same capabilities of re-sizing a component using Layout Mode are available with the SPA Editor.
  3. Return to http://localhost:4502/editor.html/content/wknd-spa-angular/us/en/home.html . Add additional Image components and try re-sizing them using the Layout option:
  4. Re-open the JSON Model http://localhost:4502/content/wknd-spa-angular/us/en.model.json and observe the columnClassNames as part of the JSON:
    The class name aem-GridColumn--default--4 indicates the component should be 4 columns wide based on a 12 column grid. More details about the responsive grid can be found here .
  5. Return to the IDE and in the ui.apps module there is a client-side library defined at ui.apps/src/main/content/jcr_root/apps/wknd-spa-angular/clientlibs/clientlib-grid . Open the file less/grid.less .
    This file determines the breakpoints ( default , tablet , and phone ) used by the Layout Container . This file is intended to be customized per project specifications. Currently the breakpoints are set to 1200px and 650px .
  6. You should be able to use the responsive capabilities and the updated rich text policies of the Text component to author a view like the following:

Congratulations!

Congratulations, you learned how to map SPA components to AEM Components and you implemented a new Image component. You also got a chance to explore the responsive capabilities of the Layout Container .
You can always view the finished code on GitHub or check the code out locally by switching to the branch Angular/map-components-solution .

Next Steps

Navigation and Routing - Learn how multiple views in the SPA can be supported by mapping to AEM Pages with the SPA Editor SDK. Dynamic navigation is implemented using Angular Router and added to an existing Header component.

Bonus - Persist configurations to source control

In many cases, especially at the beginning of an AEM project it is valuable to persist configurations, like templates and related content policies, to source control. This ensures that all developers are working against the same set of content and configurations and can ensure additional consistency between environments. Once a project reaches a certain level of maturity, the practice of managing templates can be turned over to a special group of power users.
The next few steps will take place using the Visual Studio Code IDE and VSCode AEM Sync but could be doing using any tool and any IDE that you have configured to pull or import content from a local instance of AEM.
  1. In the Visual Studio Code IDE, ensure that you have VSCode AEM Sync installed via the Marketplace extension:
  2. Expand the ui.content module in the Project explorer and navigate to /conf/wknd-spa-angular/settings/wcm/templates .
  3. Right+Click the templates folder and select Import from AEM Server :
  4. Repeat the steps to import content but select the policies folder located at /conf/wknd-spa-angular/settings/wcm/templates/policies .
  5. Inspect the filter.xml file located at ui.content/src/main/content/META-INF/vault/filter.xml .
    <!--ui.content filter.xml-->
    <?xml version="1.0" encoding="UTF-8"?>
     <workspaceFilter version="1.0">
         <filter root="/conf/wknd-spa-angular" mode="merge"/>
         <filter root="/content/wknd-spa-angular" mode="merge"/>
         <filter root="/content/dam/wknd-spa-angular" mode="merge"/>
         <filter root="/content/experience-fragments/wknd-spa-angular" mode="merge"/>
     </workspaceFilter>
    
    
    The filter.xml file is responsible for identifying the paths of nodes that will be installed with the package. Notice the mode="merge" on each of the filters which indicates that existing content will not be modified, only new content is added. Since content authors may be updating these paths, it is important that a code deployment does not overwrite content. See the FileVault documentation for more details on working with filter elements.
    Compare ui.content/src/main/content/META-INF/vault/filter.xml and ui.apps/src/main/content/META-INF/vault/filter.xml to understand the different nodes managed by each module.