Sightly api, comparing, accessing arrays with sightly in AEM

Here we will discuss about:

       ·          How to use arrays with slightly

       ·         How to compare

       ·         How to use API - Some scenarios

Arrays :

Here a sample around arrays:

// accessing a value from properties

${ properties['jcr:title'] }

// printing an array

${ aemComponent.names }

Printing the array, separated by ;

${ aemComponent.names @ join=';' }

// dynamically accessing values

<ul data-sly-list="${aemComponent.names}">

      <li>${ properties[ item ]}</li>

</ul>

Comparisons:

Here some use-cases on comparing values

<div data-sly-test="${ properties.jcr:title == 'test'}">TEST</div>

<div data-sly-test="${ properties.jcr:title != 'test'}">NOT TEST</div>

<div data-sly-test="${ properties['jcr:title'].length > 3 }">Title is longer than 3</div>

<div data-sly-test="${ properties['jcr:title'].length >= 0 }">Title is longer or equal to zero </div>

<div data-sly-test="${ properties['jcr:title'].length > aemComponent.MAX_LENGTH }">

Title is longer than the limit of ${aemComponent.MAX_LENGTH}

</div>

Now we will look at the API part and some scenarios here:

Use-API :

In my prvious article I explained that you can call methods from your custom-classes via the data-sly-use notation.
Now explaining, you can also pass in parameters from your components.

<div data-sly-use.aemComponent="${'com.myproject.components.SightlyComponent' @ firstName= 'feike', lastName = 'visser'}">

     ${aemComponent.fullname}

</div>

Java-code in the Use-Api

                    public class SightlyComponent extends WCMUse {

   // firstName and lastName are available via Bindings

  public String getFullname() {

    return get("firstName", String.class) + " " + get("lastName", String.class);

  }

}

The basic notation of the use-api looks like this is a Sightly component.

<div data-sly-use.mycomp="${ 'com.demo.MyComponent'

@ param1='value1', param2=currentPage}">

    ${mycomp.calculatedValue}

</div>

In this example you have the following:

• the class ‘com.demo.MyComponent’ is instantiated
• the name ‘mycomp’ is used
• two parameters are passed to the class
• the method getCalculatedValue() is called
•  

Now let’s look at the implementation of this; you have 5(!) options to implement this:

1. Class that implements the Use-interface
2. Class that extends WCMUse-class
3. Class that is adaptable from Resource (resource.adaptTo(YourClass))
4. Class that is adaptable from SlingHttpServletRequest (request.adaptTo(YourClass))
5. Sling models

Below I will do an example of each option, so you can see what is needed for each.

With all 5 scenarios you can switch the implementation without changing anything in your component.

Scenario-1: Class implementing Use-interface
In this case you need to implement init(), and do the all the logic in there. Via the bindings-object you can access all the objects also available on the component.

import io.sightly.java.api.Use;

public class MyComponent implements Use {

  private String value;

  @Override

  public void init(Bindings bindings) {

    // all standard objects/binding are available

    Resource resource = (Resource) bindings.get("resource");

    // parameters are passed as bindings

    String param1 = (String) bindings.get("param1");

    Page param2 = (Page) bindings.get("param2");

    value = param1 + resource.getPath() + param2.getTitle();

  }

  public String getCalculatedValue() {

    return value;

  }

}

Scenario-2: Class extending WCMUse
This option is similar like the Use-interface, but has some more helper functionality that you can use. Methods like getResource(), getCurrentPage() etc are already there for you to use.

import com.adobe.cq.sightly.WCMUse;

public class MyComponent extends WCMUse {

  private String value;

  @Override

  public void activate() {

    // helper method to get the default bindings

    Resource resource = getResource();

    // access to the parameters via get()

    String param1 = get("param1", String.class);

    Page param2 = get("param2", Page.class);

    value = param1 + resource.getPath() + param2.getTitle();

  }

  public String getCalculatedValue() {

    return value;

  }

}

Scenario-3: Class adaptable from Resource
Code example given here is how to adapt your class from a Resource. Based on that Resource-object you need to pass in the right info to your POJO. In this case you can have a plain POJO without any dependency to AEM or Sightly.

NOTE: In this option you can’t access the parameters

@Component(metatype = true, immediate = true)

@Service

public class MyComponentAdapter implements AdapterFactory {

  @Property(name = "adapters")

  protected static final String[] ADAPTER_CLASSES = { MyComponent.class.getName() };

  @Property(name = "adaptables")

  protected static final String[] ADAPTABLE_CLASSES = { Resource.class.getName() };

  @Override

  public <AdapterType> AdapterType getAdapter(Object adaptable, Class<AdapterType> type) {

    if (adaptable instanceof Resource) {

       MyComponent comp = new MyComponent();

       return (AdapterType) comp;

    }

    return null;

  }

}

Scenario-4: Class adaptable from Request
Like option 3, but now based on the request. Also it is possible here to access the parameters; they are passed in as attributes.

@Component(metatype = true, immediate = true)

@Service

public class MyComponentAdapter implements AdapterFactory {

  @Property(name = "adapters")

  protected static final String[] ADAPTER_CLASSES = { MyComponent.class.getName() };

  @Property(name = "adaptables")

  protected static final String[] ADAPTABLE_CLASSES = { SlingHttpServletRequest.class.getName() };

  @Override

  public <AdapterType> AdapterType getAdapter(Object adaptable, Class<AdapterType> type) {

    if (adaptable instanceof SlingHttpServletRequest) {

      SlingHttpServletRequest request = (SlingHttpServletRequest) adaptable;

      String param1 = (String) request.getAttribute("param1");

      Page param2 = (Page) request.getAttribute("param2");

      return (AdapterType) new MyComponent();

    }

    return null;

  }

}

Scenario-5: Sling Models
You can technically implement Options 3 and 4 with Apache Sling Models; this saves you from creating your own adapters. Here’s an example of what that would look like:

@Model(adaptables=Resource.class)

public class MyComponent {

  @Inject

  private String firstname;

  private String value;

  @PostConstruct

  public void activate() {

    value = "calculate " + firstname;

  }

  public String getCalculatedValue() {

    return value;

  }

}

Use these test case scenarios and explore slightly !!!

Cheers!!!

SonyCharan