Usage of @Via in sling models

[Nitiks25]

I understand from the documentation, that @Via is used to inject objects not available through the adaptable mapped to the model

In that case, if my adaptable is Resource.class and I have to inject SlingHttpServletRequset or SlingHttpServletResponse. I will have to use @Inject @Via to fetch it from SlingHttpServletRequest adaptable?

In that case, what is the parameter I have to pass to @Via?

In case of resource, it will be @Via ("resource") - what will it be for slingRequest?

[smacdonald2008]

Here is a much better example to extend a Core Component - we will make a HELPX article -- use this to extend the Title COMPONENT. Notice here - they are not even using @Via

package com.adobe.community.core.models;

import javax.annotation.PostConstruct;

import org.apache.commons.lang3.StringUtils;

import org.apache.sling.api.SlingHttpServletRequest;

import org.apache.sling.models.annotations.Model;

import org.apache.sling.models.annotations.injectorspecific.InjectionStrategy;

import org.apache.sling.models.annotations.injectorspecific.ScriptVariable;

import org.apache.sling.models.annotations.injectorspecific.ValueMapValue;

import com.adobe.cq.wcm.core.components.models.Title;

import com.day.cq.commons.jcr.JcrConstants;

import com.day.cq.wcm.api.Page;

import com.day.cq.wcm.api.designer.Style;

@Model(resourceType = "/apps/ExtendCore/components/content/title",

    adaptables = SlingHttpServletRequest.class,

    adapters = Title.class)

public class MyCustomTitleImpl implements Title {

    @ScriptVariable

    private Page currentPage;

    @ScriptVariable

    private Style currentStyle;

    @ValueMapValue(injectionStrategy = InjectionStrategy.OPTIONAL, name = JcrConstants.JCR_TITLE)

    private String title;

    @ValueMapValue(injectionStrategy = InjectionStrategy.OPTIONAL)

    private String type;

    /**

     * The {@link Heading} object for the type of this title.

     */

    private Heading heading;

    @PostConstruct

    private void initModel() {

        if (StringUtils.isBlank(title)) {

            title = StringUtils.defaultIfEmpty(currentPage.getPageTitle(), currentPage.getTitle());

        }

        if (heading == null) {

            heading = Heading.getHeading(type);

            if (heading == null) {

                heading = Heading.getHeading(currentStyle.get(PN_DESIGN_DEFAULT_TYPE, String.class));

            }

        }

    }

    @Override

    public String getText() {

        return "My Project - " + title;

    }

    @Override

    public String getType() {

        if (heading != null) {

            return heading.getElement();

        }

        return null;

    }

    private enum Heading {

        H1("h1"),

        H2("h2"),

        H3("h3"),

        H4("h4"),

        H5("h5"),

        H6("h6");

        private String element;

        Heading(String element) {

            this.element = element;

        }

        private static Heading getHeading(String value) {

            for (Heading heading : values()) {

                if (StringUtils.equalsIgnoreCase(heading.element, value)) {

                    return heading;

                }

            }

            return null;

        }

        public String getElement() {

            return element;

        }

    }

}

[smacdonald2008]

For anyone reading this thread and want to know how to extend a Core Component - see this HELPX article -- Extending Adobe Experience Manager Core Components

[rajeevy89244319]

Thanks Sam.

In helpx example, we are just using core title contract and then implementing the logic. In order to extend existing title implementation, what is recommended approach? Should we extended core implementation class or should we use @Via.

[smacdonald2008]

The doc example is wrong - the new HELPX artilce - follow it to learn how to extend core components - the Java part. You have to extend it as shown in the artilce. We are going to fix the example in the docs too to point to this new article. Ratna Kumar is currently testing this article.

[AEM_Forums]

Yes, I tested this article and it works!! Below is the screenshot.

Hope this helps!!

Thanks,

Ratna Kumar.