metabase-data-app-routing

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SKILL.md

---
name: metabase-data-app-routing
description: Add client-side routing (multiple pages) to an existing Metabase data-app project using the host-provided `DataAppRouter`, `DataAppLink`, and `useDataAppLocation` primitives. Use when the user has an existing data-app project and wants more than one page.
metadata:
  version: master
---

# Add routing to a data-app

A Metabase data-app bundle doesn't bundle a router library — it imports three small primitives from `@metabase/embedding-sdk-react/data-app`:

| API | Purpose |
|---|---|
| `<DataAppRouter>` | Wrap the app once. Tracks the current sub-path. Auto-detects the iframe's URL prefix; bundle author writes no basename. |
| `<DataAppLink to="/customers/42">` | Internal navigation link. Renders a real `<a href>` so middle-click / cmd-click open in a new tab. |
| `useDataAppLocation()` | Returns `{ pathname, navigate }`. Use `pathname` for match-by-equality / `startsWith` rendering; use `navigate(to)` for programmatic nav. |

That's the entire surface. **No `react-router` of any version, no `<BrowserRouter>`, no `<HashRouter>`.** The API is deliberately decoupled from any router library so a future Metabase version can swap the underlying implementation without touching bundle code.

## When to use this skill

- The user has a working data-app project — scaffolded from the data-app template, so a one-liner `vite.config.ts` (`dataAppConfig()`) and an `src/index.tsx` that exports a factory already exist. The dev preview has no in-project entry: the SDK's dev preset serves it.
- The user wants the bundle to render different content at different URLs (`/overview`, `/customers/:id`).
- **Do not use this skill** to scaffold a project from scratch — it only patches an existing data-app project. If there is no project yet, stop and tell the user to start with a new data-app scaffold before adding routing.

`dataAppConfig()` already externalizes `@metabase/embedding-sdk-react/data-app`. You do NOT need to edit `vite.config.ts` to add routing — just edit `src/App.tsx` (and add more component files as needed) per the step below.

## Step 1 — Wrap `App.tsx` with `<DataAppRouter>`

Import the routing primitives normally. `<DataAppRouter>` does NOT take a `basename` prop — it auto-detects the iframe's URL prefix (`/embed/apps/<name>`) in production and resolves to no prefix in the Vite dev preview.

`App.tsx` is pure content — no `<MetabaseProvider>` here. The SDK's dev preview entry (`DataAppDevProvider`) and the production host (`DataAppProvider`) each wrap the tree in their own realm.

```tsx
import { StaticQuestion } from "@metabase/embedding-sdk-react";
import {
  DataAppRouter,
  DataAppLink,
  useDataAppLocation,
} from "@metabase/embedding-sdk-react/data-app";

function Nav() {
  return (
    <nav style={{ padding: 16, borderBottom: "1px solid #e5e7eb" }}>
      <DataAppLink to="/" style={{ marginRight: 16 }}>Overview</DataAppLink>
      <DataAppLink to="/customers/42">Customer 42</DataAppLink>
    </nav>
  );
}

function Page() {
  const { pathname } = useDataAppLocation();

  if (pathname === "/") {
    return (
      <div style={{ padding: 24 }}>
        <h1>Overview</h1>
        <StaticQuestion questionId={1} height={360} />
      </div>
    );
  }

  const customerMatch = pathname.match(/^\/customers\/(\d+)$/);
  if (customerMatch) {
    const id = Number(customerMatch[1]);
    return (
      <div style={{ padding: 24 }}>
        <h1>Customer #{id}</h1>
        <StaticQuestion questionId={id} height={360} />
      </div>
    );
  }

  return <div style={{ padding: 24 }}>Not found: {pathname}</div>;
}

export default function App() {
  return (
    <DataAppRouter>
      <Nav />
      <Page />
    </DataAppRouter>
  );
}
```

Run `yarn dev`, click the links, watch the URL bar change. Reload at `http://localhost:5174/customers/42` and the dev preview lands on the customer route directly.

## Always preselect the default (leftmost) tab on load

**If the app presents multiple tabs (or any top-level page switcher), the base path `/` MUST render the default — leftmost / first — tab's content, never a blank page, a "Not found", or an empty shell.** This is the single most common mistake: the app boots at `/`, no branch matches, and the user sees nothing until they click a tab. Don't rely on the user (or a later navigation) to select the first tab — the default tab is the initial state.

Two equivalent ways to guarantee it, depending on whether tabs are route-backed:

- **Route-backed tabs** — give `/` an explicit branch that renders the first tab, so an unmatched/base path resolves to it:

  ```tsx
  const TABS = [
    { path: "/", label: "Overview", render: () => <Overview /> },
    { path: "/customers", label: "Customers", render: () => <Customers /> },
    { path: "/reports", label: "Reports", render: () => <Reports /> },
  ];

  function Page() {
    const { pathname } = useDataAppLocation();
    // Exact-or-prefix match; fall back to the FIRST tab so `/` (and any
    // unknown sub-path) always shows the default tab, never a blank page.
    const active =
      TABS.find((t) => t.path !== "/" && pathname.startsWith(t.path)) ?? TABS[0];
    return active.render();
  }
  ```

- **Local-state tabs (no routing)** — initialize the active-tab state to the first tab, so the very first render shows it:

  ```tsx
  const [active, setActive] = useState(TABS[0].id); // default = leftmost tab
  ```

Verify by reloading the app at its base path (`/`) with a fresh load: the leftmost tab's content must be visible immediately, and that tab must read as selected in the tab bar.

## How navigation translates to the parent URL

You don't need to do anything for this. For context:

- Bundle calls `<DataAppLink to="/customers/42">` → host's `navigate` runs `pushState` with `/embed/apps/<name>/customers/42`.
- The parent's `AppView` observes the iframe URL change and mirrors it to the parent's URL bar as `/apps/<name>/customers/42` — the `/embed` prefix is stripped because the parent's React Router route is `/apps/:name/*`, not `/embed/...`.
- Reload works because the BE serves the same `data-app.html` for every `/embed/apps/:name/*` sub-path; the iframe boots, `<DataAppRouter>` reads `window.location.pathname`, auto-detects the prefix, and starts at the right sub-path.

## What NOT to do

- **Don't add `react-router-dom`** (or any router library) to the project. The bundle doesn't need it.
- **Don't use `<BrowserRouter>` or `<HashRouter>`** inside the bundle. They run their own `setState` flow that hits the Near Membrane batching bug.
- **Don't call `window.history.pushState` directly** from inside the bundle. Use `<DataAppLink>` or `navigate` from `useDataAppLocation`.
- **Don't try to read or write the parent's URL.** The iframe's sandbox attribute blocks it by design.

## Common patterns

### Conditional render based on path

```tsx
const { pathname } = useDataAppLocation();
if (pathname === "/") return <Home />;
if (pathname.startsWith("/customers/")) return <Customer />;
return <NotFound />;
```

### Programmatic navigation (e.g. from a `<button>`)

```tsx
function OpenCustomerButton({ id }: { id: number }) {
  const { navigate } = useDataAppLocation();
  return <button onClick={() => navigate(`/customers/${id}`)}>Open #{id}</button>;
}
```

### Parsing path params manually

There's no built-in `useParams`. Match yourself:

```tsx
const { pathname } = useDataAppLocation();
const match = pathname.match(/^\/customers\/(\d+)$/);
if (match) {
  const id = Number(match[1]);
  // ...
}
```

If you find yourself doing this often, factor it into your own helper inside the bundle:

```tsx
function useCustomerIdFromPath(): number | null {
  const { pathname } = useDataAppLocation();
  const m = pathname.match(/^\/customers\/(\d+)$/);
  return m ? Number(m[1]) : null;
}
```

## Troubleshooting

| Symptom | Fix |
|---|---|
| `<DataAppLink>` renders as plain text (no clickable link) on initial load. | The bundle hasn't finished loading and the fallback path is showing. The provider wrap is supplied automatically (the SDK dev preview's `DataAppDevProvider`, or the host's `DataAppProvider`) — don't add `<MetabaseProvider>` inside the app. The fallback resolves to a real link once the bundle is up. |
| URL changes but UI doesn't. | A `<BrowserRouter>`/`<HashRouter>` is still in the tree. Strip the router library out and use `<DataAppRouter>` / `<DataAppLink>` instead — the Near Membrane interaction with React-18 batching breaks every router that runs its own `setState` inside the bundle. |
| Middle-click on a `<DataAppLink>` does nothing. | The link uses `event.button !== 0` to skip non-left clicks; check you haven't wrapped it in another component that swallows the event. |