# MappedFactory

Source: https://partfactory.dev/factories/mapped-factory/
Index of every page: https://partfactory.dev/llms.txt

Creates output values by mapping a completed input object.

Use this factory when the values you want to override are easiest to model as an object, but the final value should be a different shape or type. Each call to `make` builds the input defaults, applies deep partial overrides, and passes the completed input to the mapper function.

The mapper function can also declare dependencies, which are passed to `make` after the overrides, in the same way as `AsyncMappedFactory`. Use them for the things the mapper needs that are not part of the input, such as a client or a piece of configuration. They are given at call time rather than held by the factory, and are used as they are given, never fetched or awaited.

## Usage

```typescript
interface UrlParts {
  protocol: "https";
  host: string;
  path: string;
}

const urlFactory = new MappedFactory<UrlParts, string>(
  () => ({
    protocol: "https",
    host: "example.com",
    path: "/users",
  }),
  (parts) => `${parts.protocol}://${parts.host}${parts.path}`,
);

const defaultUrl = urlFactory.make();
// "https://example.com/users"

const apiUrl = urlFactory.make({ path: "/api/users" });
// "https://example.com/api/users"

// The same factory with the host supplied as a dependency:
const hostedUrlFactory = new MappedFactory<
  Omit<UrlParts, "host">,
  string,
  { server: { host: string } }
>(
  () => ({
    protocol: "https",
    path: "/users",
  }),
  (parts, { server }) => `${parts.protocol}://${server.host}${parts.path}`,
);

const hostedUrl = hostedUrlFactory.make({ path: "/api/users" }, { server });
// "https://test.example.com/api/users"
```

## Source

Source file: [`src/mapped/mapped-factory.ts`](https://github.com/KensioSoftware/part-factory/blob/main/src/mapped/mapped-factory.ts)