Problem Statement:
The problem addressed in this article is the need to avoid writing boilerplate code in Sling models. Writing boilerplate code such as getters and setters can be time-consuming and can lead to code duplication, which can make the code difficult to maintain. Therefore, developers need a way to simplify the process of writing Sling models by removing the boilerplate code.
Requirement:
Avoid boilerplate code like getters and setters and make sling models look a lot simpler.
Introduction:
You can annotate any field with @Getter and/or @Setter, to let Lombok generate the default getter/setter automatically.
A default getter simply returns the field and is named getFoo if the field is called foo (or isFoo if the field’s type is boolean). A default setter is named setFoo if the field is called foo, returns void, and takes 1 parameter of the same type as the field. It simply sets the field to this value.
The generated getter/setter method will be public unless you explicitly specify an AccessLevel, as shown in the example below. Legal access levels are PUBLIC, PROTECTED, PACKAGE, and PRIVATE.
You can also put a @Getter and/or @Setter annotation on a class. In that case, it’s as if you annotate all the non-static fields in that class with the annotation.
Use Lombok in sling model to avoid writing getters and setters and make the class look simpler and remove all the boilerplate code from the Java class
Most of the time we usually create Sling models to grab resource properties and use them on sightly for representation. In other cases, we usually do some custom changes on these injected properties.
Using Lombok on the Sling model removes all the boilerplate code related to all the injected fields and increases maintainability.
Lombok @Getter and @Setter
Create LombokExample Interface:
package com.mysite.core.models;
import org.osgi.annotation.versioning.ConsumerType;
@ConsumerType
public interface LombokExample {
default String getName() {
throw new UnsupportedOperationException();
}
}
Create LombokExampleImpl – Sling model
Lombok @Getter – creates the get method and @Setter creates the set method
In Sightly call useObject.name/path / jcrTitle you will get resource properties
the following class increases the readability and maintainability of the model
package com.mysite.core.models.impl;
import javax.annotation.PostConstruct;
import org.apache.commons.lang3.StringUtils;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.models.annotations.Default;
import org.apache.sling.models.annotations.Exporter;
import org.apache.sling.models.annotations.Model;
import org.apache.sling.models.annotations.injectorspecific.InjectionStrategy;
import org.apache.sling.models.annotations.injectorspecific.OSGiService;
import org.apache.sling.models.annotations.injectorspecific.Self;
import org.apache.sling.models.annotations.injectorspecific.SlingObject;
import org.apache.sling.models.annotations.injectorspecific.ValueMapValue;
import org.apache.sling.models.factory.ModelFactory;
import com.adobe.cq.export.json.ExporterConstants;
import com.mysite.core.bean.ExampleBean;
import com.mysite.core.bean.ExampleConstBean;
import com.mysite.core.models.LombokExample;
import lombok.Getter;
@Model(adaptables = SlingHttpServletRequest.class, adapters = {
LombokExample.class }, resourceType = WithoutLombokImpl.RESOURCE_TYPE)
@Exporter(name = ExporterConstants.SLING_MODEL_EXPORTER_NAME, extensions = ExporterConstants.SLING_MODEL_EXTENSION)
public class LombokExampleImpl implements LombokExample {
public static final String RESOURCE_TYPE = "mysite/components/content/lombok";
@Self
private SlingHttpServletRequest request;
@SlingObject
private Resource currentResource;
@SlingObject
private ResourceResolver resourceResolver;
@ValueMapValue
@Getter
private String name;
@ValueMapValue(injectionStrategy = InjectionStrategy.OPTIONAL)
@Getter
private String path;
@ValueMapValue(name = "jcr:title", injectionStrategy = InjectionStrategy.OPTIONAL)
@Default(values = StringUtils.EMPTY)
@Getter
private String jcrTitle;
@OSGiService
private ModelFactory modelFactory;
@PostConstruct
private void init() {
}
}
Lombok – @Data
Use @Data as a sling model when you are trying to adapt the current resource or some resource result into a different sling model (which doesn’t have any OOTB sling script variable or services like SlingHttpServletRequest, resource, etc.)
package com.mysite.core.models.impl;
import com.adobe.cq.wcm.core.components.models.contentfragment.ContentFragment;
import com.drew.lang.annotations.Nullable;
import lombok.Data;
import org.apache.sling.api.SlingHttpServletRequest;
import org.apache.sling.models.annotations.DefaultInjectionStrategy;
import org.apache.sling.models.annotations.Model;
import org.apache.sling.models.annotations.injectorspecific.InjectionStrategy;
import org.apache.sling.models.annotations.injectorspecific.ValueMapValue;
import javax.annotation.PostConstruct;
@Model(adaptables = SlingHttpServletRequest.class, defaultInjectionStrategy = DefaultInjectionStrategy.OPTIONAL)
@Data
public class CFModelImpl{
@ValueMapValue(name = ContentFragment.PN_PATH, injectionStrategy = InjectionStrategy.OPTIONAL)
@Nullable
private String fragmentPath;
@ValueMapValue(name = ContentFragment.PN_ELEMENT_NAMES, injectionStrategy = InjectionStrategy.OPTIONAL)
@Nullable
private String[] elementNames;
@ValueMapValue(name = ContentFragment.PN_VARIATION_NAME, injectionStrategy = InjectionStrategy.OPTIONAL)
@Nullable
private String variationName;
@ValueMapValue(name = ContentFragment.PN_DISPLAY_MODE, injectionStrategy = InjectionStrategy.OPTIONAL)
@Nullable
private String displayMode;
@PostConstruct
private void initModel() {
}
}
Call Adapt to this new class using ModelFactory(recommended for error handling) to get the injected resource properties
@PostConstruct
private void init() {
CFModelImpl cfModel = modelFactory.getModelFromWrappedRequest(request, currentResource, CFModelImpl.class);
cfModel.getFragmentPath();
cfModel.getElementNames();
}
@Data is a convenient shortcut annotation that bundles the features of @ToString, @EqualsAndHashCode, @Getter / @Setter
In other words, @Data generates all the boilerplate that is normally associated with simple POJOs (Plain Old Java Objects) and beans:
- Getters for all fields, setters for all non-final fields
- Appropriate toString equals and hashCode implementations that involve the fields of the class,
- Constructor that initializes all final fields
- All fields marked as transient will not be considered for hashCode and equals. All static fields will be skipped entirely (not considered for any of the generated methods, and no setter/getter will be made for them).
Create Example Bean with @Data annotation
package com.mysite.core.bean;
import lombok.Data;
@Data
public class ExampleBean {
private String name;
private String value;
}
Create an object for ExampleBean and set some values
@PostConstruct
private void init() {
ExampleBean exampleBean = new ExampleBean();
exampleBean.setName("Name");
exampleBean.setValue("Kiran");
}
Create a constructor to only name field
define the field name field as final
package com.mysite.core.bean;
import lombok.Data;
@Data
public class ExampleConstBean {
private final String name;
private String value;
}
Create an object ExampleConstBean
In the below example, you can see we are able to call the constructor for the name field
@PostConstruct
private void init() {
ExampleConstBean exampleConstBean = new ExampleConstBean("Name");
exampleConstBean.setValue("Kiran");
}
You can also use @allargsconstructor if you want a constructor for all the fields
if you want certain fields constructor then declare those fields as final
cons:
the parameters of these annotations (such as callSuper, include field names, and exclude) cannot be set with @Data. If you need to set non-default values for any of these parameters, just add those annotations explicitly;
AEM best practices and development guide 