feat: add schema validator middleware

.changeset/cyan-penguins-bathe.md

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+---
+'@hono/schema-validator': major
+---
+
+Add @hono/schema-validator middleware.  
+This middleware leverages [TypeSchema](https://typeschema.com), offering an abstraction layer that facilitates interaction with a variety of validation libraries through a unified interface. Consequently, there is no immediate requirement to develop a dedicated middleware for each validation library. This not only reduces maintenance efforts but also extends support to validation libraries that may currently lack compatibility.

packages/schema-validator/CHANGELOG.md

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+# @hono/schema-validator
+
+## 1.0.0
+
+### Major Changes

packages/schema-validator/README.md

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+# Universal validator middleware for Hono
+
+The validator middleware using [TypeSchema](https://typeschema.com) for [Hono](https://honojs.dev) applications.
+You can write a schema with various schema libraries and validate the incoming values.
+
+The preferred validation library must be additionally installed.  
+The list of supported validation libraries can be found at [TypeSchema](https://typeschema.com/#coverage).
+
+## Usage
+
+```ts
+import { z } from 'zod'
+import { schemaValidator, type ValidationError } from '@hono/schema-validator'
+
+const schema = z.object({
+  name: z.string(),
+  age: z.number(),
+})
+
+app.post('/author', schemaValidator('json', schema), (c) => {
+  const data = c.req.valid('json')
+  return c.json({
+    success: true,
+    message: `${data.name} is ${data.age}`,
+  })
+})
+
+app.onError(async (err, c) => {
+  if (err instanceof ValidationError) {
+    return c.json(err, err.status)
+  }
+  return c.text('Internal Server Error', 500)
+})
+```
+
+Hook:
+
+```ts
+app.post(
+  '/post',
+  schemaValidator('json', schema, (result, c) => {
+    if (!result.success) {
+      return c.text('Invalid!', 400)
+    }
+  })
+  //...
+)
+```
+
+## Author
+
+Sebastian Wessel <https://github.com/sebastianwessel>
+
+## License
+
+MIT

packages/schema-validator/jest.config.js

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+module.exports = require('../../jest.config.js')

packages/schema-validator/package.json

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+{
+  "name": "@hono/schema-validator",
+  "version": "0.0.0",
+  "description": "Validator middleware for multiple schema validation libraries based on schema.com",
+  "main": "dist/cjs/index.js",
+  "module": "dist/esm/index.js",
+  "types": "dist/esm/index.d.ts",
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "test": "jest",
+    "build:cjs": "tsc -p tsconfig.cjs.json",
+    "build:esm": "tsc -p tsconfig.esm.json",
+    "build": "rimraf dist && yarn build:cjs && yarn build:esm",
+    "prerelease": "yarn build && yarn test",
+    "release": "yarn publish"
+  },
+  "license": "MIT",
+  "publishConfig": {
+    "registry": "https://registry.npmjs.org",
+    "access": "public"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/honojs/middleware.git"
+  },
+  "homepage": "https://github.com/honojs/middleware",
+  "peerDependencies": {
+    "hono": ">=3.9.0"
+  },
+  "dependencies": {
+    "@decs/typeschema": "^0.12.2"
+  },
+  "devDependencies": {
+    "hono": "^3.11.7",
+    "jest": "^29.7.0",
+    "rimraf": "^5.0.5",
+    "typescript": "^5.3.3",
+    "zod": "3.19.1"
+  }
+}

packages/schema-validator/src/index.ts

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+import type { Infer, InferIn, Schema, ValidationIssue } from '@decs/typeschema'
+import { validate } from '@decs/typeschema'
+import type { Context, Env, MiddlewareHandler, TypedResponse, ValidationTargets } from 'hono'
+import { HTTPException } from 'hono/http-exception'
+import { validator } from 'hono/validator'
+
+export type Hook<T, E extends Env, P extends string, O = {}> = (
+  result:
+    | { success: true; data: T; inputData: unknown }
+    | { success: false; issues: Array<ValidationIssue>; inputData: unknown },
+  c: Context<E, P>,
+) => Response | Promise<Response> | void | Promise<Response | void> | TypedResponse<O>
+
+type HasUndefined<T> = undefined extends T ? true : false
+
+
+type HTTPExceptionOptions = {
+    res?: Response;
+    message?: string;
+    data?:unknown
+};
+
+export class ValidationError extends HTTPException {
+
+  private data:unknown
+  constructor(
+    options?: HTTPExceptionOptions,
+  ) {
+    /* Calling the constructor of the parent class (Error) and passing the message. */
+    super(400,options)
+    this.data=options?.data
+    Error.captureStackTrace(this, this.constructor)
+
+    Object.setPrototypeOf(this, ValidationError.prototype)
+    this.name = this.constructor.name
+  }
+
+  getData(){
+    return this.data
+  }
+
+  toJSON(){
+    return {
+      status: this.status,
+      message: this.message,
+      data: this.data
+    }
+  }
+}
+
+export const schemaValidator = <
+  T extends Schema,
+  Target extends keyof ValidationTargets,
+  E extends Env,
+  P extends string,
+  I = InferIn<T>,
+  O = Infer<T>,
+  V extends {
+    in: HasUndefined<I> extends true ? { [K in Target]?: I } : { [K in Target]: I }
+    out: { [K in Target]: O }
+  } = {
+    in: HasUndefined<I> extends true ? { [K in Target]?: I } : { [K in Target]: I }
+    out: { [K in Target]: O }
+  },
+>(
+  target: Target,
+  schema: T,
+  hook?: Hook<Infer<T>, E, P>,
+): MiddlewareHandler<E, P, V> =>
+  validator(target, async (value, c) => {
+    const result = await validate(schema, value)
+
+    if (hook) {
+      const hookResult = hook({ inputData: value, ...result }, c)
+      if (hookResult) {
+        if (hookResult instanceof Response || hookResult instanceof Promise) {
+          return hookResult
+        }
+        if ('response' in hookResult) {
+          return hookResult.response
+        }
+      }
+    }
+
+    if (!result.success) {
+       throw new ValidationError({ message: 'Custom error message',data:{issues:result.issues,target} })
+    }
+
+    const data = result.data as Infer<T>
+    return data
+  })

packages/schema-validator/test/index.test.ts

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+import { Hono } from 'hono'
+import type { Equal, Expect } from 'hono/utils/types'
+import { z } from 'zod'
+import { schemaValidator } from '../src'
+
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+type ExtractSchema<T> = T extends Hono<infer _, infer S> ? S : never
+
+describe('Basic', () => {
+  const app = new Hono()
+
+  const jsonSchema = z.object({
+    name: z.string(),
+    age: z.number(),
+  })
+
+  const querySchema = z
+    .object({
+      name: z.string().optional(),
+    })
+    .optional()
+
+  const route = app.post(
+    '/author',
+    schemaValidator('json', jsonSchema),
+    schemaValidator('query', querySchema),
+    (c) => {
+      const data = c.req.valid('json')
+      const query = c.req.valid('query')
+
+      return c.json({
+        success: true,
+        message: `${data.name} is ${data.age}`,
+        queryName: query?.name,
+      })
+    }
+  )
+
+  type Actual = ExtractSchema<typeof route>
+  type Expected = {
+    '/author': {
+      $post: {
+        input: {
+          json: {
+            name: string
+            age: number
+          }
+        } & {
+          query?:
+            | {
+                name?: string | undefined
+              }
+            | undefined
+        }
+        output: {
+          success: boolean
+          message: string
+          queryName: string | undefined
+        }
+      }
+    }
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  type verify = Expect<Equal<Expected, Actual>>
+
+  it('Should return 200 response', async () => {
+    const req = new Request('http://localhost/author?name=Metallo', {
+      body: JSON.stringify({
+        name: 'Superman',
+        age: 20,
+      }),
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+    const res = await app.request(req)
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({
+      success: true,
+      message: 'Superman is 20',
+      queryName: 'Metallo',
+    })
+  })
+
+  it('Should return 400 response', async () => {
+    const req = new Request('http://localhost/author', {
+      body: JSON.stringify({
+        name: 'Superman',
+        age: '20',
+      }),
+      method: 'POST',
+    })
+    const res = await app.request(req)
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(400)
+    const data:{success:boolean} = await res.json()
+    expect(data['success']).toBe(false)
+  })
+})
+
+describe('With Hook', () => {
+  const app = new Hono()
+
+  const schema = z.object({
+    id: z.number(),
+    title: z.string(),
+  })
+
+  app.post(
+    '/post',
+    schemaValidator('json', schema, (result, c) => {
+      if (!result.success) {
+        return c.text(`${(result.inputData as {id:string}).id} is invalid!`, 400)
+      }
+      const data = result.data
+      return c.text(`${data.id} is valid!`)
+    }),
+    (c) => {
+      const data = c.req.valid('json')
+      return c.json({
+        success: true,
+        message: `${data.id} is ${data.title}`,
+      })
+    }
+  )
+
+  it('Should return 200 response', async () => {
+    const req = new Request('http://localhost/post', {
+      body: JSON.stringify({
+        id: 123,
+        title: 'Hello',
+      }),
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+    const res = await app.request(req)
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(200)
+    expect(await res.text()).toBe('123 is valid!')
+  })
+
+  it('Should return 400 response', async () => {
+    const req = new Request('http://localhost/post', {
+      body: JSON.stringify({
+        id: '123',
+        title: 'Hello',
+      }),
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+      },
+    })
+    const res = await app.request(req)
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(400)
+    expect(await res.text()).toBe('123 is invalid!')
+  })
+})

packages/schema-validator/tsconfig.cjs.json

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+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "CommonJS",
+    "declaration": false,
+    "outDir": "./dist/cjs"
+  }
+}

packages/schema-validator/tsconfig.esm.json

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+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "module": "ESNext",
+    "declaration": true,
+    "outDir": "./dist/esm"
+  }
+}