Override third party module service contract

Question

There is third party custom module. For add entries they used service contract entities. I need to add one more entry. Don't want to touch third party module. How can i extend their interface and module and after save data in table. I've created field in table. But unable to override interface and Model and save entry. I know there is concept Extension Attributes for this but not getting how to archive.

Please help me on this.

Answer 1

Here you have to use the Extension attribute concept but ensure that the 3-rd party Data interface Vendor\Module\Api\Data\{PovideName}Interface has two functions public function getExtensionAttributes and setExtensionAttributes.

Then you can use the extension attribute.

If you using a different database table then you have to implement service contact for this custom table, then expose your data interface to as 3rd party extension extension attribute. An example:

<extension_attributes for="Magento\Catalog\Api\Data\ProductInterface">
    <attribute code="stock_item" type="Magento\CatalogInventory\Api\Data\StockItemInterface" />
</extension_attributes>

Here you can see Magento\CatalogInventory\Api\Data\StockItemInterface as extension attribute field for Magento\Catalog\Api\Data\ProductInterface"

See https://devdocs.magento.com/guides/v2.4/extension-dev-guide/extension_attributes/adding-attributes.html#extension-attributes-configuration

And you can better understand from fooman article: https://store.fooman.co.nz/blog/an-introduction-to-extension-attributes.html