Implement GraphQL code generation

GraphQL code generation automatically creates strongly typed code based on your schema and operations. It generates type-safe code artifacts using the graphql-codegen package, ensuring consistency between the front-end implementation and the underlying GraphQL API.

You can follow this topic to manually implement GraphQL code generation in your app using the graphql-codegen package.

To implement GraphQL code generation:

Add the following dev dependencies to your app's package.json file, then install them with the npm install command.

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"graphql": "^16.11.0",
"graphql-tag": "^2.12.6",
"@graphql-codegen/cli": "^5.0.7",
"@graphql-codegen/typescript": "^4.1.6",
"@graphql-codegen/typescript-operations": "^4.6.1",
"@graphql-codegen/typescript-react-query": "^6.1.1"
"ts-node": "^10.9.1",
"tsconfig-paths": "^4.1.2",
"dotenv": "^16.5.0"

Enable fetching of GraphQL introspection data by adding the following example script to the /scripts/fetch-graphql-introspection-data.ts file:

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import { GraphQLRequestClient } from "@sitecore-content-sdk/nextjs/client";
import fs from "fs";
import { getIntrospectionQuery } from "graphql";
// Load environment variables using 'dotenv/config' before importing scConfig
// If for local development you are using `.env.local` you can load it passing its path:
// require('dotenv').config({ path: '.env.local' });
import "dotenv/config";
import scConfig from "sitecore.config";

// construct the GraphQL endpoint URL using edgeUrl and contextId from the config
const graphQLEndpoint = `${scConfig.api.edge.edgeUrl}/v1/content/api/graphql/v1?sitecoreContextId=${scConfig.api.edge.contextId}`;

const client = new GraphQLRequestClient(graphQLEndpoint);

console.log(
  `Fetch graphql introspection data from ${scConfig.api.edge.edgeUrl}/v1/content/api/graphql/v1 ...`
);

client
  .request(getIntrospectionQuery())
  .then((result) => {
    fs.writeFile(
      "./.sitecore/GraphQLIntrospectionResult.json",
      JSON.stringify(result, null, 2),
      (err) => {
        if (err) {
          console.error("Error writing GraphQLIntrospectionResult file", err);
          return;
        }

        console.log("GraphQL Introspection Data successfully fetched!");
      }
    );
  })
  .catch((e) => {
    console.error(e);
  });

This file fetches the GraphQL introspection data exposed by SItecore instance's GraphQL API and stores it in ./sitecore/GraphQLIntrospectionResult.json. This file is used to generate the TypeScript types.

To import scConfig properly in the above script, add the following extension in the tsconfig.scripts.json file:

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{
    "extends": "./tsconfig.json",
    "ts-node": {
        "require": [
            "tsconfig-paths/register"
        ]
    },
    "compilerOptions": {
        "module": "commonjs"
    }
}

Add the following script in the scripts section of your application's package.json file:

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"graphql:update": "ts-node --project tsconfig.scripts.json ./scripts/fetch-graphql-introspection-data.ts"

Configure graphql-codegen by creating a graphql-codegen.yml at the root of your app containing the following:

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overwrite: true # Overwrite existing files
documents: 'src/**/*.graphql' # Adjust the path to your GraphQL documents; remove it if you don't have .graphql files in your solution
schema: '.sitecore/GraphQLIntrospectionResult.json' # the path to your introspection result file
generates:
  .sitecore/graphql-types.ts: # The output file for generated types
    plugins:
      - 'typescript' # Generates TypeScript types for GraphQL operations
      - 'typescript-operations' # Generates TypeScript types for GraphQL operations
      - 'typescript-react-query' # Generates React Query hooks for GraphQL operations

Run the following command to generate the src/temp/graphql-types.ts file containing the necessary types.
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```
npx graphql-codegen --config graphql-codegen.yml
```

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