Dynamic Attribute

You can add properties to your model and develop custom logic for them using dynamic attributes without changing the model class itself. They offer a way to create fresh data and access it without using a different service. Dynamic attributes are temporary pieces of information that are not stored in the database.

In this scenario, no column will be created in the database, and as a result, no values will be saved there. It is referred to as a dynamic or non-persistent characteristic.

Key features of Dynamic Attribute :

The persistence type is set to dynamic persistent type=”dynamic”.
The attributeHandler points to a bean that must handle the DynamicAttributeHandler interface.
One item type can have any number of dynamic attributes.

Practical Use Case: Show a new variable a cart age by taking the difference of the cart creation date and current date on the cart page.

We will fulfill the above requirement in following three steps:

Step 1: Define a new attribute cartAge in the cart model in item.xml and make persistent type=”dynamic”.

<itemtype code="Cart" autocreate="false" generate="false">
<description>Extending cart type with additional attributes.</description>
<attributes>
<attribute autocreate="true" qualifier="cartAge" type="java.lang.Integer">
<modifiers read=”true” write="true"/>
<persistence type="dynamic"/>
<description>Dynamic attribute for cart age</description>
</attribute>
</attributes>
</itemtype>

Step 2: Define the Attributehandler which should be the bean id of the class which implements DynamicAttributeHandler.

<itemtype code="Cart" autocreate="false" generate="false">
<description>Extending cart type with additional attributes.</description>
<attributes>
<attribute autocreate="true" qualifier="cartAge" type="java.lang.Integer">
<modifiers read=”true” write="true"/>
<persistence type="dynamic" attributeHandler="cartAgeAttributeHandler"/>
<description>Dynamic attribute for cart age</description>
</attribute>
</attributes>
</itemtype>

Step 3: Define the custom attribute handler class: We will define the attribute handler class by extending the AbstractDynamicAttributeHandler or by implementing DynamicAttributeHandler.

package com.training.attributehandlers;
import de.hybris.platform.servicelayer.model.attribute.AbstractDynamicAttributeHandler;
import java.time.Duration;
import java.time.ZoneId; import
java.time.ZonedDateTime;
import org.springframework.stereotype.Component;
import concerttours.model.CartModel;
@Component
public class CartAgeAttributeHandler extends AbstractDynamicAttributeHandler<Long, CartModel>
{
@Override public Long get(final CartModel model)
{
if (model.getCreationDate() == null)
{ return null; }
final ZonedDateTime cartCreationDate = model.getCreationDate().toInstant().atZone(ZoneId.systemDefault());
final ZonedDateTime now = ZonedDateTime.now();
final Duration duration = Duration.between(now, cartCreationDate);
return Long.valueOf(duration.toDays());
}
}

Step 4: Associate the CartAgeAttributeHandler class to the bean id defined in item.xml file (attributeHandler="cartAgeAttributeHandler").