feat: class validator middleware for Hono (#788)

* setup middleware package

* add implementation middleware

* add documentation + updae tsconfig for decorator handling

* add tests

* fix format class-validator middleware

* Add Readme

* Update changelog & changeset

* update changelog 2

* update changelog 2

* fix working directory ci

* rm jest dependencies

change to tsup for build

fix ci name

* revert changes not related to class-validator

* remove the changeset since Changesets will add a changeset automatically

* package description

.changeset/spotty-donuts-yawn.md

@@ -0,0 +1,5 @@
+---
+'@hono/class-validator': major
+---
+
+First release

.github/workflows/ci-class-validator.yml

@@ -0,0 +1,25 @@
+name: ci-class-validator
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'packages/class-validator/**'
+  pull_request:
+    branches: ['*']
+    paths:
+      - 'packages/class-validator/**'
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./packages/class-validator
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20.x
+      - run: yarn install --frozen-lockfile
+      - run: yarn build
+      - run: yarn test

package.json

@@ -10,6 +10,7 @@
   "scripts": {
     "build:hello": "yarn workspace @hono/hello build",
     "build:zod-validator": "yarn workspace @hono/zod-validator build",
+    "build:class-validator": "yarn workspace @hono/class-validator build",
     "build:arktype-validator": "yarn workspace @hono/arktype-validator build",
     "build:qwik-city": "yarn workspace @hono/qwik-city build",
     "build:graphql-server": "yarn workspace @hono/graphql-server build",

packages/class-validator/README.md

@@ -0,0 +1,56 @@
+# Class-validator middleware for Hono
+
+The validator middleware using [class-validator](https://github.com/typestack/class-validator) for [Hono](https://github.com/honojs/hono) applications.
+
+## Usage
+
+```ts
+import { classValidator } from '@hono/class-validator'
+import { IsInt, IsString } from 'class-validator'
+
+class CreateUserDto {
+  @IsString()
+  name!: string;
+
+  @IsInt()
+  age!: number;
+}
+
+
+const route = app.post('/user', classValidator('json', CreateUserDto), (c) => {
+  const user = c.req.valid('json')
+  return c.json({ success: true, message: `${user.name} is ${user.age}` })
+})
+```
+
+With hook:
+
+```ts
+import { classValidator } from '@hono/class-validator'
+import { IsInt, IsString } from 'class-validator'
+
+class CreateUserDto {
+  @IsString()
+  name!: string;
+
+ @IsInt()
+  age!: number;
+}
+
+app.post(
+  '/user', classValidator('json', CreateUserDto, (result, c) => {
+    if (!result.success) {
+      return c.text('Invalid!', 400)
+     }
+  })
+  //...
+)
+```
+
+## Author
+
+**Pr0m3ht3us** - https://github.com/pr0m3th3usex
+
+## License
+
+MIT

packages/class-validator/package.json

@@ -0,0 +1,47 @@
+{
+  "name": "@hono/class-validator",
+  "packageManager": "[email protected]",
+  "description": "Validator middleware using class-validator",
+  "version": "0.1.0",
+  "type": "module",
+  "main": "dist/index.js",
+  "module": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "import": "./dist/index.js",
+      "types": "./dist/index.d.ts"
+    }
+  },
+  "scripts": {
+    "test": "vitest --run",
+    "build": "rimraf dist && tsup ./src/index.ts --format esm,cjs --dts",
+    "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"
+  },
+  "devDependencies": {
+    "hono": "^4.0.10",
+    "rimraf": "^5.0.5",
+    "tsup": "^8.3.5",
+    "typescript": "^5.3.3",
+    "vitest": "^1.4.0"
+  },
+  "dependencies": {
+    "class-transformer": "^0.5.1",
+    "class-validator": "^0.14.1",
+    "reflect-metadata": "^0.2.2"
+  }
+}

packages/class-validator/src/index.ts

@@ -0,0 +1,158 @@
+import 'reflect-metadata'
+import { validator } from 'hono/validator'
+import { ClassConstructor, ClassTransformOptions, plainToClass } from 'class-transformer'
+import { Context, Env, Input, MiddlewareHandler, TypedResponse, ValidationTargets } from 'hono'
+import { ValidationError, validate } from 'class-validator'
+
+/**
+ * Hono middleware that validates incoming data using class-validator(https://github.com/typestack/class-validator).
+ *
+ * ---
+ *
+ * No Hook
+ *
+ * ```ts
+ * import { classValidator } from '@hono/class-validator'
+ * import { IsInt, IsString } from 'class-validator'
+ *
+ * class CreateUserDto {
+ *  @IsString()
+ *  name!: string;
+ *
+ *  @IsInt()
+ *  age!: number;
+ * }
+ *
+ *
+ * const route = app.post('/user', classValidator('json', CreateUserDto), (c) => {
+ *   const user = c.req.valid('json')
+ *   return c.json({ success: true, message: `${user.name} is ${user.age}` })
+ * })
+ * ```
+ *
+ * ---
+ * Hook
+ *
+ * ```ts
+ * import { classValidator } from '@hono/class-validator'
+ * import { IsInt, IsString } from 'class-validator'
+ *
+ * class CreateUserDto {
+ *  @IsString()
+ *  name!: string;
+ *
+ *  @IsInt()
+ *  age!: number;
+ * }
+ *
+ * app.post(
+ *   '/user',
+ *   classValidator('json', CreateUserDto, (result, c) => {
+ *     if (!result.success) {
+ *       return c.text('Invalid!', 400)
+ *     }
+ *   })
+ *   //...
+ * )
+ * ```
+ */
+
+type Hook<
+  T,
+  E extends Env,
+  P extends string,
+  Target extends keyof ValidationTargets = keyof ValidationTargets,
+  O = object
+> = (
+  result: ({ success: true } | { success: false; errors: ValidationError[] }) & {
+    data: T
+    target: Target
+  },
+  c: Context<E, P>
+) => Response | void | TypedResponse<O> | Promise<Response | void | TypedResponse<O>>
+
+type HasUndefined<T> = undefined extends T ? true : false
+
+type HasClassConstructor<T> = ClassConstructor<any> extends T ? true : false
+
+export type StaticObject<T extends ClassConstructor<any>> = {
+  [K in keyof InstanceType<T>]: HasClassConstructor<InstanceType<T>[K]> extends true
+    ? StaticObject<InstanceType<T>[K]>
+    : InstanceType<T>[K]
+}
+
+const parseAndValidate = async <T extends ClassConstructor<any>>(
+  dto: T,
+  obj: object,
+  options: ClassTransformOptions
+): Promise<
+  { success: false; errors: ValidationError[] } | { success: true; output: InstanceType<T> }
+> => {
+  // tranform the literal object to class object
+  const objInstance = plainToClass(dto, obj, options)
+  // validating and check the errors, throw the errors if exist
+
+  const errors = await validate(objInstance)
+  // errors is an array of validation errors
+  if (errors.length > 0) {
+    return {
+      success: false,
+      errors,
+    }
+  }
+
+  return { success: true, output: objInstance as InstanceType<T> }
+}
+
+export const classValidator = <
+  T extends ClassConstructor<any>,
+  Output extends InstanceType<T> = InstanceType<T>,
+  Target extends keyof ValidationTargets = keyof ValidationTargets,
+  E extends Env = Env,
+  P extends string = string,
+  In = StaticObject<T>,
+  I extends Input = {
+    in: HasUndefined<In> extends true
+      ? {
+          [K in Target]?: K extends 'json'
+            ? In
+            : HasUndefined<keyof ValidationTargets[K]> extends true
+            ? { [K2 in keyof In]?: ValidationTargets[K][K2] }
+            : { [K2 in keyof In]: ValidationTargets[K][K2] }
+        }
+      : {
+          [K in Target]: K extends 'json'
+            ? In
+            : HasUndefined<keyof ValidationTargets[K]> extends true
+            ? { [K2 in keyof In]?: ValidationTargets[K][K2] }
+            : { [K2 in keyof In]: ValidationTargets[K][K2] }
+        }
+    out: { [K in Target]: Output }
+  },
+  V extends I = I
+>(
+  target: Target,
+  dataType: T,
+  hook?: Hook<Output, E, P, Target>,
+  options: ClassTransformOptions = { enableImplicitConversion: false }
+): MiddlewareHandler<E, P, V> =>
+  // @ts-expect-error not typed well
+  validator(target, async (data, c) => {
+    const result = await parseAndValidate(dataType, data, options)
+
+    if (hook) {
+      const hookResult = hook({ ...result, data, target }, c)
+      if (hookResult instanceof Response || hookResult instanceof Promise) {
+        if ('response' in hookResult) {
+          return hookResult.response
+        }
+        return hookResult
+      }
+    }
+
+    if (!result.success) {
+      return c.json({ errors: result.errors }, 400)
+    }
+
+    return result.output
+  })