Override a parent theme in vendor with a child theme in app Magento 2.3

Question

I have made a theme that is a child to a customized theme that is a child of Luma.

My theme lives in:

app/design/frontend/{mycompany}/{mythemename}/

My themes parent lives in:

vendor/{vendorcompany}/{vendorthemedirectory}/

The parent is overriding:

Magento_Catalog/templates/product/view/gallery.phtml among other files, like so:

vendor/{vendorcompany}/{vendorthemedirectory}/Magento_Catalog/templates/product/view/gallery.phtml

I want to override this override but I can't seem get the directory structure of my child theme right or maybe I'm missing something else.

My first thought is to create it like so:

app/design/frontend/{mycompany}/{mythemename}/{vendorcompany}_{vendorthemedirectory}/Magento_Catalog/templates/product/view/gallery.phtml

But that doesn't seem to work. gallery.phtml is still loading from the parent. I've tried a few combinations of directory structure without luck. How do I override the override?

Answer 1

Hello Adam and welcome on Magento Stack Exchange.

Is your custom theme declared as a child of the parent?

For doing this you have to include in your custom theme's theme.xml this code:

<theme xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Config/etc/theme.xsd">
    <title>Your custom theme</title>
        <parent>Parent/theme</parent> <!-- You find the correct name in registration.php of parent theme -->
    <media>
        <preview_image>media/preview.png</preview_image>
    </media>
 </theme>

Once you ensured that you have correctly declared the dependency from parent theme, you should enable your custom theme from Content > Design > Configuration

Then put your file in this path: app/design/frontend/{mycompany}/{mythemename}/Magento_Catalog/templates/product/view/gallery.phtml

Hope this could help to point you on the right way