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sidebar_position: 5
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# Type generation

AppKit can automatically generate TypeScript types for your SQL queries, providing end-to-end type safety from database to UI.

## Goal

Generate type-safe TypeScript declarations for query keys, parameters, and result rows.

All generated files live in `shared/appkit-types/`, one per plugin (e.g. `analytics.d.ts`). They use [`declare module`](https://www.typescriptlang.org/docs/handbook/declaration-merging.html#module-augmentation) to augment existing interfaces, so the types apply globally — you never need to import them. TypeScript auto-discovers them through `"include": ["shared/appkit-types"]` in your tsconfig.

## Vite plugin: `appKitTypesPlugin`

The recommended approach is to use the Vite plugin, which watches your SQL files and regenerates types automatically during development.

### Configuration

- `outFile?: string` - Output file path (default: `shared/appkit-types/analytics.d.ts`)
- `watchFolders?: string[]` - Folders to watch for SQL files (default: `["../config/queries"]`)

### Example

```ts
// client/vite.config.ts
import { defineConfig } from "vite";
import react from "@vitejs/plugin-react";
import { appKitTypesPlugin } from "@databricks/appkit";

export default defineConfig({
  plugins: [
    react(),
    appKitTypesPlugin({
      watchFolders: ["../config/queries"],
    }),
  ],
});
```

### Important nuance

When the frontend is served through AppKit in dev mode, AppKit's dev server already includes `appKitTypesPlugin()` internally. You still want it in your client build pipeline if you run `vite build` separately.

## CLI: `npx @databricks/appkit generate-types`

For manual type generation or CI/CD pipelines, use the CLI command:

```bash
# Requires DATABRICKS_WAREHOUSE_ID (or pass as 3rd arg)
npx @databricks/appkit generate-types [rootDir] [outFile] [warehouseId]
```

### Examples

- Generate types using warehouse ID from environment

  ```bash
  npx @databricks/appkit generate-types . shared/appkit-types/analytics.d.ts
  ```

- Generate types using warehouse ID explicitly

  ```bash
  npx @databricks/appkit generate-types . shared/appkit-types/analytics.d.ts abc123...
  ```

- Force regeneration (skip cache)

  ```bash
  npx @databricks/appkit generate-types --no-cache
  ```

## How it works

The type generator:

1. Scans your `config/queries/` folder for `.sql` files
2. Parses SQL parameter annotations (e.g., `-- @param startDate DATE`)
3. Connects to your Databricks SQL Warehouse to infer result column types
4. Generates TypeScript interfaces for query parameters and results
5. Creates a `QueryRegistry` type for type-safe query execution

## Using generated types

Once types are generated, your IDE will provide autocomplete and type checking:

```tsx
import { useAnalyticsQuery } from "@databricks/appkit-ui/react";
import { sql } from "@databricks/appkit-ui/js";

// TypeScript knows "users_list" is a valid query key
// and what parameters it expects
const { data } = useAnalyticsQuery("users_list", {
  status: sql.string("active"),
  limit: sql.number(50),
});

// TypeScript knows the shape of the result rows
data?.forEach(row => {
  console.log(row.email); // ✓ autocomplete works
});
```

## See also

- [Plugins](../plugins/analytics.md) - Analytics plugin configuration
- [API Reference](https://databricks.com/devhub/docs/api/appkit-ui) - Complete UI components API documentation