Components Reference Guide components-reference-guide

Components are at the core of building an experience in AEM. The Core Components and the AEM Project Archetype make it simple to get started with a tool set of ready-made, robust components. The WKND Tutorial takes the developer through how to use these tools and how to build custom components to create an AEM site.

Because the WKND Tutorial covers most use cases, this document is intended only as a supplement to those resources. It gives in-depth technical specifics about how components are structured and configured in AEM and is not intended as a getting started guide.

Overview overview

This section covers key concepts and issues as an introduction to the details needed when developing your own components.

Planning planning

Before starting to actually configure or code your component you should ask:

Reusing Existing Components reusing-components

Before you invest time in creating an entirely new component, consider customizing or extending existing components. The Core Components offer a suite of flexible, robust, and well-tested production-ready components.

Extending Core Components extending-core-components

The Core Components also offer clear customization patterns that you can use to adapt them to the needs of your own project.

Overlaying Components overlying-components

Components can also be redefined with an overlay based on the search path logic. However in such case, the Sling Resource Merger will not be triggered and /apps must define the entire overlay.

Extending Component Dialogs extending-component-dialogs

It is also possible to override a component dialog using the Sling Resource Merger and defining the property sling:resourceSuperType.

This means you only need to redefine the required differences, as opposed to redefining the entire dialog.

Content Logic and Rendering Markup content-logic-and-rendering-markup

Your component is rendered with HTML. Your component must define the HTML needed to take the required content and then render it as required, on both the author and publish environments.

It is recommended to keep the code responsible for markup and rendering separate from the code that controls the logic used to select the component’s content.

This philosophy is supported by HTL, a templating language that is purposely limited to ensure a real programming language is used to define the underlying business logic. This mechanism highlights the code that is called for a given view and, if necessary, allows specific logic for different views of the same component.

This (optional) logic can be implemented in different ways and is invoked from HTL with specific commands:

Component Structure structure

The structure of an AEM component is powerful and flexible. The main parts are:

Resource Type resource-type

A key element of the structure is the resource type.

This is an abstraction that helps to ensure that even when the look and feel changes over time, that the intention stays the time.

Component Definition component-definition

The definition of a component can be broken down as follows:

Vital Properties vital-properties

Component Icon component-icon

The icon or abbreviation for the component is defined via JCR properties of the component when the component is created by the developer. These properties are evaluated in the following order and the first valid property found is used.

If none of the above properties (cq:icon, abbreviation, cq:icon.png or cq:icon.svg) are found on the component:

To cancel the inheritance of icons from super components, setting an empty abbreviation property on the component will revert to the default behavior.

The Component Console displays how the icon for a particular component is defined.

SVG Icon Example svg-icon-example

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "https://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
<svg version="1.1" id="Layer_1" xmlns="https://www.w3.org/2000/svg" xmlns:xlink="https://www.w3.org/1999/xlink" x="0px" y="0px"
     width="20px" height="20px" viewBox="0 0 20 20" enable-background="new 0 0 20 20" xml:space="preserve">
    <ellipse cx="5" cy="5" rx="3" ry="3" fill="#707070"/>
    <ellipse cx="15" cy="5" rx="4" ry="4" fill="#707070"/>
    <ellipse cx="5" cy="15" rx="5" ry="5" fill="#707070"/>
    <ellipse cx="15" cy="15" rx="4" ry="4" fill="#707070"/>
</svg>

Properties and Child Nodes of a Component properties-and-child-nodes-of-a-component

Many of the nodes/properties needed to define a component are common to both UIs, with differences remaining independent so that your component can work in both environments.

A component is a node of type cq:Component and has the following properties and child nodes:

If you look at the Text component, you can see several of these elements:

Properties of particular interest include:

Child nodes of particular interest include:

Dialogs dialogs

Dialogs are a key element of your component as they provide an interface for authors to configure the component on a content page and provide input for that component. See the authoring documentation for details on how content authors interact with components.

Depending on the complexity of the component your dialog may need one or more tabs.

Dialogs for AEM components:

Within the dialog, individual fields are defined:

Design Dialogs design-dialogs

Design dialogs are similar to the dialogs used to edit and configure content, but they provide the interface for template authors to pro-configure and provide design details for that component on a page template. Page templates are then used by the content authors to create content pages. See the template documentation for details on how templates are created.

Design dialogs are used when editing a page template, though they are not needed for all components. For example, the Title and Image Components both have design dialogs, whereas the Social Media Sharing Component does not.

Coral UI and Granite UI coral-and-granite

Coral UI and Granite UI define the look and feel of AEM.

Granite UI provides a large range of the basic widgets needed to create your dialog on the authoring environment. When necessary you can extend this selection and create your own widget.

For additional details see the following resources:

Customizing Dialog Fields customizing-dialog-fields

To create a widget for use in a component dialog requires you to create a Granite UI field component.

If you consider your dialog as a simple container for a form element, then you can also see the primary content of your dialog content as form fields. Creating a new form field requires you to create a resource type; this is equivalent to creating a component. To help you in that task, Granite UI offers a generic field component to inherit from (using sling:resourceSuperType):

/libs/granite/ui/components/coral/foundation/form/field

More specifically Granite UI provides a range of field components that are suitable for use in dialogs, or more generally speaking in forms.

Once you have created your resource type, you can instantiate your field by adding a new node in your dialog, with the property sling:resourceType referring to the resource type you have just introduced.

Access to Dialog Fields access-to-dialog-fields

You can also use render conditions (rendercondition) to control who has access to specific tabs/fields in your dialog; for example:

+ mybutton
  - sling:resourceType = granite/ui/components/coral/foundation/button
  + rendercondition
    - sling:resourceType = myapp/components/renderconditions/group
    - groups = ["administrators"]

Using Components using-components

After you have create a component, you must enable it to use it. Using it shows how the structure of the component relates to the structure of the resulting content in the repository.

Adding your Component to the Template adding-your-component-to-the-template

After a component has been defined it must be made available for use. To make a component available for use in a template, you must enable the component in the policy of the layout container of the template.

See the template documentation for details on how templates are created.

Components and the Content They Create components-and-the-content-they-create

If we create and configure an instance of the Title component on the page: /content/wknd/language-masters/en/adventures/extreme-ironing.html

Then we can see the structure of the content created within the repository:

In particular, if you look at the actual text of a Title Component:

The properties defined are dependent on the individual definitions. Although they can be more complex than above they still follow the same basic principles.

Component Hierarchy and Inheritance component-hierarchy-and-inheritance

Components within AEM are subject to the Resource Type Hierarchy. This is used to extend components using the property sling:resourceSuperType. This enables the component to inherit from another component.

See the section Reusing Components for more information.

Edit Behavior edit-behavior

This section explains how to configure the edit behavior of a component. This includes attributes such as actions available for the component, characteristics of the in.place editor, and the listeners related to events on the component.

The edit behavior of a component is configured by adding a cq:editConfig node of type cq:EditConfig below the component node (of type cq:Component) and by adding specific properties and child nodes. The following properties and child nodes are available:

There are many existing configurations in AEM. You can easily search for specific properties or child nodes using the Query tool in CRXDE Lite.

Component Placeholders component-placeholders

Components must always render some HTML that is visible to the author, even when the component has no content. Otherwise it might visually disappear from the editor’s interface, making it technically present but invisible on the page and in the editor. In such a case the authors won’t be able to select and interact with the empty component.

For this reason, components should render a placeholder as long as they do not render any visible output when the page is rendered in the page editor (when the WCM mode is edit or preview).
The typical HTML markup for a placeholder is the following:

<div class="cq-placeholder" data-emptytext="Component Name"></div>

The typical HTL script that renders the above placeholder HTML is the following:

<div class="cq-placeholder" data-emptytext="${component.properties.jcr:title}"
     data-sly-test="${(wcmmode.edit || wcmmode.preview) && isEmpty}"></div>

In the previous example, isEmpty is a variable that is true only when the component has no content and is invisible to the author.

To avoid repetition, Adobe recommends that implementers of components use an HTL template for these placeholders, like the one provided by the Core Components.

The usage of the template in the previous link is then done with the following line of HTL:

<sly data-sly-use.template="core/wcm/components/commons/v1/templates.html"
     data-sly-call="${template.placeholder @ isEmpty=!model.text}"></sly>

In the previous example, model.text is the variable that is true only when the content has content and is visible.

An example usage of this template can be seen in the Core Components, such as in the Title Component.

Configuring with cq:EditConfig Child Nodes configuring-with-cq-editconfig-child-nodes

Dropping Assets into a Dialog - cq:dropTargets cq-droptargets

The cq:dropTargets node (node type nt:unstructured) defines the drop target that can accept a drop from an asset dragged from the content finder. It is a node of type cq:DropTargetConfig.

The child node of type cq:DropTargetConfig defines a drop target in the component.

In-Place Editing - cq:inplaceEditing cq-inplaceediting

An in-place editor allows the user to edit content directly in the content flow, without the need to open a dialog. For example, the standard Text and Title components both have an in-place editor.

An in-place editor is not necessary/meaningful for every component type.

The cq:inplaceEditing node (node type cq:InplaceEditingConfig) defines an in-place editing configuration for the component. It can have the following properties:

The following configuration enables the in-place editing of the component and defines plaintext as the editor type:

    <cq:inplaceEditing
        jcr:primaryType="cq:InplaceEditingConfig"
        active="{Boolean}true"
        editorType="plaintext"/>

Handling Field Events - cq:listeners cq-listeners

The method of handling events on dialog fields is done with listeners in a custom client library.

To inject logic into your field, you should:

To achieve this you need to know about the underlying widget library with which you want to interact. See the Coral UI documentation to identify to which event you want to react.

The cq:listeners node (node type cq:EditListenersConfig) defines what happens before or after an action on the component. The following table defines its possible properties.

The event handler can be implemented with a custom implementation. For example, (where project.customerAction is a static method):

afteredit = "project.customerAction"

The following example is equivalent to the REFRESH_INSERTED configuration:

afterinsert="function(path, definition) { this.refreshCreated(path, definition); }"

With the following configuration the page is refreshed after the component has been deleted, edited, inserted or moved:

    <cq:listeners
        jcr:primaryType="cq:EditListenersConfig"
        afterdelete="REFRESH_PAGE"
        afteredit="REFRESH_PAGE"
        afterinsert="REFRESH_PAGE"
        afterMove="REFRESH_PAGE"/>

Field Validation field-validation

Field validation in Granite UI and the Granite UI widgets is done by using the foundation-validation API. See the foundation-valdiation Granite documentation for details.

Detecting Availability of the Dialog dialog-ready

If you have a custom JavaScript that must be run only when the dialog is available and ready, you should listen for the dialog-ready event.

This event is triggered whenever the dialog loads (or re-loads) and is ready for use, which means whenever there is a change (create/update) in the DOM of the dialog.

dialog-ready can be used to hook in JavaScript custom code that performs customizations on the fields inside a dialog or similar tasks.

Preview Behavior preview-behavior

The WCM Mode cookie is set when switching to Preview mode even when the page is not refreshed.

For components with a rendering that are sensitive to the WCM Mode, they need to be defined to refresh themselves specifically, then rely on the value of the cookie.

Documenting Components documenting-components

As a developer, you want easy access to component documentation so that you can quickly understand the component’s:

For this reason, it is quite easy to make any existing documentation markdown you have available within the component itself.

All you need to do is place a README.md file in the component structure.

This markdown will then be displayed in the Component Console.

The supported markdown is the same as that for Content Fragments.