Overriding classes

Virtually always, you will want to keep part of the default functionality and only modify some aspect of the existing class. This is how the theme is usually extended.

For example, when overriding ProductCard, suppose we want to keep the default ScandiPWA implementation of the component, but with one change - we don't want the product images to be visible in the product cards.

In order to do this, we will make sure our class extends the base ProductCard class. Then, it will inherit the default functionality from its parent class, and we will be able to override any part of it.

All we need to do is import the original ProductCard class, extend it, and re-export the modified version. But there is one challenge: as mentioned before, if we try to import from Component/ProductCard/ProductCard.component, the import mechanism will resolve this to our overridden implementation, not the desired original class. Hence, it is impossible to import the original class from the parent theme using the Component alias if we intend to override this class.

The solution is to use another alias, SourceComponent to extend classes from the parent theme.

override: component/ProductCard/ProductCard.component.js
import { PureComponent } from 'react';
​
// we use the SourceComponent alias to explicitly import from the parent theme
// (if we would use Component/ProductCard/... instead, we would be trying to import
// the current file, which would result in an error)
import { ProductCard as SourceProductCard } from 'SourceComponent/ProductCard/ProductCard.component';
​
// we imported the original ProductCard class defined in the parent theme.
// we aliased the import to `SourceProductCard` to indicate that SourceProductCard
// is the parent theme version of the class
​
// you should always copy over the namespace declaration when overriding an existing class
// to avoid breaking plugins
/** @namespace Component/ProductCard/Component */
export class ProductCard extends SourceProductCard { // we can now extend SourceProductCard,
    // and override any methods we want to change
​
    // this method overrides the default implementation provided in the original ProductCard class
    renderPicture()  {
        // returning null in a React component means rendering nothing
        return null;
    }
}
​
// we now export the extended and modified version of the class
export default ProductCard;

Indeed, we can check that now, the ProductCard component is the same as in the default theme, with one change: it no longer has a picture.

Overriding Constructors

ScandiPWA uses magic __construct functions instead of constructors. This is done to enable overriding of these functions, which you can override like any other function.