# Hono Stacks

Hono makes easy things easy and hard things easy.
It is suitable for not just only returning JSON.
But it's also great for building the full-stack application including REST API servers and the client.

## RPC

Hono's RPC feature allows you to share API specs with little change to your code.
The client generated by `hc` will read the spec and access the endpoint type-safety.

The following libraries make it possible.

- Hono - API Server
- [Zod](https://zod.dev) - Validator
- [Zod Validator Middleware](https://github.com/honojs/middleware/tree/main/packages/zod-validator)
- `hc` - HTTP Client

We can call the set of these components the **Hono Stack**.
Now let's create an API server and a client with it.

## Writing API

First, write an endpoint that receives a GET request and returns JSON.

```ts twoslash
import { Hono } from 'hono'

const app = new Hono()

app.get('/hello', (c) => {
  return c.json({
    message: `Hello!`,
  })
})
```

## Validation with Zod

Validate with Zod to receive the value of the query parameter.

![](/images/sc01.gif)

```ts
import { zValidator } from '@hono/zod-validator'
import * as z from 'zod'

app.get(
  '/hello',
  zValidator(
    'query',
    z.object({
      name: z.string(),
    })
  ),
  (c) => {
    const { name } = c.req.valid('query')
    return c.json({
      message: `Hello! ${name}`,
    })
  }
)
```

## Sharing the Types

To emit an endpoint specification, export its type.

::: warning

For the RPC to infer routes correctly, all included methods must be chained, and the endpoint or app type must be inferred from a declared variable. For more, see [Best Practices for RPC](https://hono.dev/docs/guides/best-practices#if-you-want-to-use-rpc-features).

:::

```ts{1,17}
const route = app.get(
  '/hello',
  zValidator(
    'query',
    z.object({
      name: z.string(),
    })
  ),
  (c) => {
    const { name } = c.req.valid('query')
    return c.json({
      message: `Hello! ${name}`,
    })
  }
)

export type AppType = typeof route
```

## Client

Next. The client-side implementation.
Create a client object by passing the `AppType` type to `hc` as generics.
Then, magically, completion works and the endpoint path and request type are suggested.

![](/images/sc03.gif)

```ts
import { AppType } from './server'
import { hc } from 'hono/client'

const client = hc<AppType>('/api')
const res = await client.hello.$get({
  query: {
    name: 'Hono',
  },
})
```

The `Response` is compatible with the fetch API, but the data that can be retrieved with `json()` has a type.

![](/images/sc04.gif)

```ts
const data = await res.json()
console.log(`${data.message}`)
```

Sharing API specifications means that you can be aware of server-side changes.

![](/images/ss03.png)

## With React

You can create applications on Cloudflare Pages using React.

The API server.

```ts
// functions/api/[[route]].ts
import { Hono } from 'hono'
import { handle } from 'hono/cloudflare-pages'
import * as z from 'zod'
import { zValidator } from '@hono/zod-validator'

const app = new Hono()

const schema = z.object({
  id: z.string(),
  title: z.string(),
})

type Todo = z.infer<typeof schema>

const todos: Todo[] = []

const route = app
  .post('/todo', zValidator('form', schema), (c) => {
    const todo = c.req.valid('form')
    todos.push(todo)
    return c.json({
      message: 'created!',
    })
  })
  .get((c) => {
    return c.json({
      todos,
    })
  })

export type AppType = typeof route

export const onRequest = handle(app, '/api')
```

The client with React and React Query.

```tsx
// src/App.tsx
import {
  useQuery,
  useMutation,
  QueryClient,
  QueryClientProvider,
} from '@tanstack/react-query'
import { AppType } from '../functions/api/[[route]]'
import { hc, InferResponseType, InferRequestType } from 'hono/client'

const queryClient = new QueryClient()
const client = hc<AppType>('/api')

export default function App() {
  return (
    <QueryClientProvider client={queryClient}>
      <Todos />
    </QueryClientProvider>
  )
}

const Todos = () => {
  const query = useQuery({
    queryKey: ['todos'],
    queryFn: async () => {
      const res = await client.todo.$get()
      return await res.json()
    },
  })

  const $post = client.todo.$post

  const mutation = useMutation<
    InferResponseType<typeof $post>,
    Error,
    InferRequestType<typeof $post>['form']
  >({
    mutationFn: async (todo) => {
      const res = await $post({
        form: todo,
      })
      return await res.json()
    },
    onSuccess: async () => {
      queryClient.invalidateQueries({ queryKey: ['todos'] })
    },
    onError: (error) => {
      console.log(error)
    },
  })

  return (
    <div>
      <button
        onClick={() => {
          mutation.mutate({
            id: Date.now().toString(),
            title: 'Write code',
          })
        }}
      >
        Add Todo
      </button>

      <ul>
        {query.data?.todos.map((todo) => (
          <li key={todo.id}>{todo.title}</li>
        ))}
      </ul>
    </div>
  )
}
```