Best Practices for Creating Extensible and Secure Sling Models in AEM

Problem Statement:

What is the best way to use the Sling model?


Need to create a sling model with best practices like OOTB components and increase the extensibility of the component and security.


The Sling model is a basic POJO, the class is annotated with @Model and the adaptable class. Fields that need to be injected are annotated with recommended injectors.

Its commonly used for injecting component resources and handling manipulation on those properties

Create a Sling model interface

Create a Sling model interface class and impl package with its implementation this helps in the long run when we are trying to write extra features by creating versions for the same component:

Create Interface Class – HelloWorldModel

In the below code, we can see an interface that extends the Component and a few constants and methods which increases the security

package com.mysite.core.models;

import com.adobe.cq.wcm.core.components.models.Component;
import org.osgi.annotation.versioning.ConsumerType;

public interface HelloWorldModel extends Component {
     * if required by multiple classes
    String PN_PARENT_PAGE = "navigationRoot";

     * Returns the hellow world message
     * @return the message containing resourcetype and page path.
    default String getMessage() {
        throw new UnsupportedOperationException();
Create Implementation Class – HelloWorldModelImpl
package com.mysite.core.models.impl;

import static;
import java.util.Optional;
import javax.annotation.PostConstruct;
import com.adobe.cq.export.json.ExporterConstants;
import com.mysite.core.models.HelloWorldModel;

@Model(adaptables = SlingHttpServletRequest.class, adapters = {HelloWorldModel.class}, resourceType = HelloWorldModelImpl.RESOURCE_TYPE)
@Exporter(name = ExporterConstants.SLING_MODEL_EXPORTER_NAME , extensions = ExporterConstants.SLING_MODEL_EXTENSION)
public class HelloWorldModelImpl implements HelloWorldModel {

    public static final String RESOURCE_TYPE = "mysite/components/content/hello";

    @ValueMapValue(name=PROPERTY_RESOURCE_TYPE, injectionStrategy=InjectionStrategy.OPTIONAL)
    @Default(values="No resourceType")
    protected String resourceType;

    private Resource currentResource;

    private ResourceResolver resourceResolver;

    private String message;

    protected void init() {
        PageManager pageManager = resourceResolver.adaptTo(PageManager.class);
        String currentPagePath = Optional.ofNullable(pageManager)
                .map(pm -> pm.getContainingPage(currentResource))

        message = "Hello World!\n"
                + "Resource type is: " + resourceType + "\n"
                + "Current page is:  " + currentPagePath + "\n";

    public String getMessage() {
        return message;

Implementation class will implement and adapters to interface class HellWorldModel

Please make sure

  1. The default adaption(adaptables) strategy is preferably SlingHTTPRequest compared or Resource
  2. We should always add Jackson exporter so that the model will be export ready
  3. Make sure always use relevant injector instead of @inject annotations refer to all the injectors:
  4. if multiple fields have the optional injection, then add the following code to the class to make all the variables optional
@Model(adaptables = SlingHttpServletRequest.class, defaultInjectionStrategy = DefaultInjectionStrategy.OPTIONAL)

Project structure

AEM Core Image component:




Advantages of this pattern:

  1. Create multiple versions of the component
  2. Improves code readability
  3. Don’t have to retouch the existing implementation but can extend the parent class to improve functionality
  4. Easy to revert back to the production code
  5. Improves unit testing and regression testing

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