# Define Handlers

You can define custom handlers for your custom endpoints or for existing endpoints (aka OCC Endpoints) of spartacus-mock.

1. Create a handlers file `src/mock-server/handlers.ts`
2. Create a folder `src/mock-server/mock-data` where all your mock-data lives
3. In the handlers file you can define all your custom handlers like in this example:

```ts
// src/mock-server/handlers.ts
import { getDefaultRoutes } from '@valantic/spartacus-mock';
import {
  HttpHandler,
  HttpResponse,
  PathParams,
  StrictRequest,
  http,
} from 'msw';
import { environment } from '../environments/environment';
import { countryList } from './mock-data/countries';

// default routes defined in the spartacus-mock library
// for custom routes, use your getRoutes function explained above
const defaultRoutes = getDefaultRoutes(environment);

export const handlers = (): RestHandler[] => {
  return [
    http.get<{}, { foo: number; bar: string }>(
      defaultRoutes.languages,
      ({ request, params }) => {
        return HttpResponse.json(languageList());
      }
    ),
  ];
};
```

> Defining a custom handler for an existing route (aka OCC Endpoint) will override the default handler for this route.

4. Create a file `src/mock-server/mock-data/languages.ts`
5. Add a `languageList` function to return the mock-data for the languages endpoint:

```ts
// src/mock-server/mock-data/languages.ts
import { createLanguage } from '@valantic/spartacus-mock';
import { Occ } from '@spartacus/core';

// you can use the `createLanguage` function from our library or create your own
export const languageList = (): Occ.LanguageList => {
  return {
    languages: [
      createLanguage({
        isocode: 'en',
        name: 'English',
        nativeName: 'English',
      }),
      createLanguage({
        isocode: 'de',
        name: 'German',
        nativeName: 'Deutsch',
      }),
    ],
  };
};
```

6. Append your handlers to the mockConfig in your `main.ts` file

```ts
// src/main.ts
// your custom defined handlers
import { handlers } from './mock-server/handlers';

async function prepare(): Promise<
  ServiceWorkerRegistration | undefined
> {
  if (environment.mockServer) {
    const { prepareMock } = await import(
      /* webpackChunkName: "mock-server" */ '@valantic/spartacus-mock'
    );

    const mockConfig: MockConfig = {
      enableWorker: environment.mockServer || false,
      environment,
      handlers: handlers(),
    };

    return prepareMock(mockConfig);
  }

  return Promise.resolve(undefined);
}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://valantic.gitbook.io/spartacus-mock/examples/define-handlers.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.