Version: 3.x

Change a resolver behavior

This guide shows you how to properly override GraphQL field resolvers while maintaining clean, maintainable code.

As an example, we will change the way the Product meta_description field value is generated.

Create dedicated GraphQL module

First, you have to create a GraphQL module. For that, you can follow the process detailed in Extend the GraphQL schema.

In this example, we have a base GraphQL module for ProductMetaDescription which does not do anything yet:

extensions/acme-extension/modules/productmetadescription/index.ts
import { createGraphQLModule } from "@front-commerce/core/graphql";

export default createGraphQLModule({
  namespace: "ProductMetaDescription",
});

Set the module dependency

Before being able to inject your custom resolver logic, you first need to find the module that defines the resolver for the field. In our example, the Product meta_description is resolved by the resolver provided by the Magento2/Catalog/Products module. As a result, the Magento2/Catalog/Products module must be added as a dependency of our custom module:

extensions/acme-extension/modules/productmetadescription/index.ts
import { createGraphQLModule } from "@front-commerce/core/graphql";

export default createGraphQLModule({
  namespace: "ProductMetaDescription",
  dependencies: ["Magento2/Catalog/Products"],
});

Implement your custom resolver logic

Our custom module can now provide a resolver with a custom logic in your extension's runtime.

extensions/acme-extension/modules/productmetadescription/runtime.ts
export default createGraphQLRuntime({
  resolvers: {
    Product: {
      meta_description: (product) => {
        // your implementation here
        return "my custom description";
      },
    },
  },
});

For this resolver to be taken into account, you will need to include the GraphQL Runtime import in your GraphQL Module:

import { createGraphQLModule } from "@front-commerce/core/graphql";

export default createGraphQLModule({
  namespace: "ProductMetaDescription",
  dependencies: ["Magento2/Catalog/Products"],
  runtime: () => import("./runtime"),
});

This custom resolver will now be merged with the existing ones and the meta_description will be resolved with our custom implementation instead of the default one.