Working with Sling Models in AEM
Adobe Experience Manager (AEM) is a powerful content management system built on the Apache Sling framework. At the heart of modern AEM development lies the Sling Models API—a convenient way to map Java classes to Adobe JCR nodes or request objects. Sling Models offer a cleaner, annotation-driven alternative to traditional WCMUsePojo and JSP scripting.
In this blog, we’ll dive into what Sling Models are, how to use them effectively, and why they’re the preferred method for backend logic in AEM components.
📌 What are Sling Models?
Sling Models are POJOs (Plain Old Java Objects) annotated with Sling-specific annotations that help inject data from JCR (Java Content Repository) or HTTP requests. They reduce boilerplate code and simplify the logic in AEM components by separating data logic from presentation.
Introduced in AEM 6.0 and enhanced significantly in later versions, Sling Models are now a core part of AEM development.
🛠️ Basic Sling Model Structure
Here’s a simple example of a Sling Model for a Title Component:
java
@Model(adaptables = Resource.class)
public class TitleModel {
@ValueMapValue
private String title;
public String getTitle() {
return title;
}
}
This model automatically maps the title property from the JCR node to the Java field, with no extra code needed to fetch it.
🔁 Adaptables and AdaptTo
The @Model annotation defines which objects can be used to create instances of the model. The most common adaptables are:
Resource
SlingHttpServletRequest
Example:
java
@Model(adaptables = SlingHttpServletRequest.class)
You can use request.adaptTo(TitleModel.class) to get an instance of the model in a servlet or script.
🧩 Common Annotations
@ValueMapValue: Injects a value from the resource’s value map (JCR properties).
@Inject: Injects services, request attributes, or properties.
@Default: Provides a default value if the property is missing.
@Named: Used when the field name and property name differ.
@PostConstruct: Executes logic after all injections are completed.
Example:
java
@PostConstruct
protected void init() {
if (title == null) {
title = "Default Title";
}
}
🌐 Sling Models Exporter
For modern AEM projects using SPA frameworks like React or Angular, Sling Models can be exported as JSON using the Sling Model Exporter (@Exporter annotation). This makes it easier to integrate AEM with headless or hybrid front-ends.
Example:
java
@Model(adaptables = Resource.class,
adapters = TitleModel.class,
resourceType = "aem-demo/components/title",
defaultInjectionStrategy = DefaultInjectionStrategy.OPTIONAL)
@Exporter(name = "jackson", extensions = "json")
public class TitleModel {
@ValueMapValue
private String title;
public String getTitle() {
return title;
}
}
This can now be accessed via /content/page/jcr:content/root/title.model.json.
✅ Benefits of Using Sling Models
Clean separation of logic and presentation
Reduces boilerplate code
Better testability
Reusability across multiple components
Easy integration with headless front-ends via JSON exporter
⚠️ Common Pitfalls to Avoid
Forgetting to include the correct adaptables (e.g., Resource or SlingHttpServletRequest)
Using incorrect injection annotations (@ValueMapValue vs @Inject)
Missing dependency configurations in bnd.bnd or pom.xml files
Not registering the Sling Model with the correct resource type
🏁 Conclusion
Sling Models are essential for clean and efficient AEM component development. They provide a robust and scalable way to encapsulate business logic, retrieve JCR content, and interact with services—all with minimal code. Whether you’re building traditional HTL components or headless APIs, mastering Sling Models will greatly enhance your AEM development workflow.
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