feat(ajv-validator): Add Ajv validator middleware (#794)

Author: ikhvost

.changeset/two-poets-vanish.md

@@ -0,0 +1,5 @@
+---
+'@hono/ajv-validator': patch
+---
+
+Add Ajv validator middleware

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

@@ -0,0 +1,25 @@
+name: ci-ajv-validator
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'packages/ajv-validator/**'
+  pull_request:
+    branches: ['*']
+    paths:
+      - 'packages/ajv-validator/**'
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./packages/ajv-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

@@ -38,6 +38,7 @@
     "build:effect-validator": "yarn workspace @hono/effect-validator build",
     "build:conform-validator": "yarn workspace @hono/conform-validator build",
     "build:casbin": "yarn workspace @hono/casbin build",
+    "build:ajv-validator": "yarn workspace @hono/ajv-validator build",
     "build": "run-p 'build:*'",
     "lint": "eslint 'packages/**/*.{ts,tsx}'",
     "lint:fix": "eslint --fix 'packages/**/*.{ts,tsx}'",

packages/ajv-validator/README.md

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+# Ajv validator middleware for Hono
+
+Validator middleware using [Ajv](https://github.com/ajv-validator/ajv) for [Hono](https://honojs.dev) applications.
+Define your schema with Ajv and validate incoming requests.
+
+## Usage
+
+No Hook:
+
+```ts
+import { type JSONSchemaType } from 'ajv';
+import { ajvValidator } from '@hono/ajv-validator';
+ 
+const schema: JSONSchemaType<{ name: string; age: number }> = {
+  type: 'object',
+  properties: {
+    name: { type: 'string' },
+    age: { type: 'number' },
+  },
+  required: ['name', 'age'],
+  additionalProperties: false,
+} as const;
+
+const route = app.post('/user', ajvValidator('json', schema), (c) => {
+  const user = c.req.valid('json');
+  return c.json({ success: true, message: `${user.name} is ${user.age}` });
+});
+```
+
+Hook:
+
+```ts
+import { type JSONSchemaType } from 'ajv';
+import { ajvValidator } from '@hono/ajv-validator';
+
+const schema: JSONSchemaType<{ name: string; age: number }> = {
+  type: 'object',
+  properties: {
+    name: { type: 'string' },
+    age: { type: 'number' },
+  },
+  required: ['name', 'age'],
+  additionalProperties: false,
+};
+
+app.post(
+  '/user',
+  ajvValidator('json', schema, (result, c) => {
+    if (!result.success) {
+      return c.text('Invalid!', 400);
+    }
+  })
+  //...
+);
+```
+
+## Author
+
+Illia Khvost <https://github.com/ikhvost>
+
+## License
+
+MIT

packages/ajv-validator/package.json

@@ -0,0 +1,49 @@
+{
+  "name": "@hono/ajv-validator",
+  "version": "0.0.0",
+  "description": "Validator middleware using Ajv",
+  "type": "module",
+  "module": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "test": "vitest --run",
+    "build": "tsup ./src/index.ts --format esm,cjs --dts",
+    "publint": "publint",
+    "release": "yarn build && yarn test && yarn publint && yarn publish"
+  },
+  "exports": {
+    ".": {
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.js"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
+    }
+  },
+  "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": {
+    "ajv": ">=8.12.0",
+    "hono": ">=3.9.0"
+  },
+  "devDependencies": {
+    "ajv": ">=8.12.0",
+    "hono": "^4.4.12",
+    "tsup": "^8.1.0",
+    "vitest": "^1.6.0"
+  }
+}

packages/ajv-validator/src/index.ts

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+import type { Context, Env, MiddlewareHandler, ValidationTargets } from 'hono';
+import { validator } from 'hono/validator';
+import { Ajv, type JSONSchemaType, type ErrorObject } from 'ajv';
+
+type Hook<T, E extends Env, P extends string> = (
+  result: { success: true; data: T } | { success: false; errors: ErrorObject[] },
+  c: Context<E, P>
+) => Response | Promise<Response> | void;
+
+/**
+ * Hono middleware that validates incoming data via an Ajv JSON schema.
+ *
+ * ---
+ *
+ * No Hook
+ *
+ * ```ts
+ * import { type JSONSchemaType } from 'ajv';
+ * import { ajvValidator } from '@hono/ajv-validator';
+ *
+ * const schema: JSONSchemaType<{ name: string; age: number }> = {
+ *   type: 'object',
+ *   properties: {
+ *     name: { type: 'string' },
+ *     age: { type: 'number' },
+ *   },
+ *   required: ['name', 'age'],
+ *   additionalProperties: false,
+ * };
+ *
+ * const route = app.post('/user', ajvValidator('json', schema), (c) => {
+ *   const user = c.req.valid('json');
+ *   return c.json({ success: true, message: `${user.name} is ${user.age}` });
+ * });
+ * ```
+ *
+ * ---
+ * Hook
+ *
+ * ```ts
+ * import { type JSONSchemaType } from 'ajv';
+ * import { ajvValidator } from '@hono/ajv-validator';
+ *
+ * const schema: JSONSchemaType<{ name: string; age: number }> = {
+ *   type: 'object',
+ *   properties: {
+ *     name: { type: 'string' },
+ *     age: { type: 'number' },
+ *   },
+ *   required: ['name', 'age'],
+ *   additionalProperties: false,
+ * };
+ *
+ * app.post(
+ *   '/user',
+ *   ajvValidator('json', schema, (result, c) => {
+ *     if (!result.success) {
+ *       return c.text('Invalid!', 400);
+ *     }
+ *   })
+ *   //...
+ * );
+ * ```
+ */
+export function ajvValidator<
+  T,
+  Target extends keyof ValidationTargets,
+  E extends Env = Env,
+  P extends string = string
+>(
+  target: Target,
+  schema: JSONSchemaType<T>,
+  hook?: Hook<T, E, P>
+): MiddlewareHandler<
+  E,
+  P,
+  {
+    in: { [K in Target]: T };
+    out: { [K in Target]: T };
+  }
+> {
+  const ajv = new Ajv();
+  const validate = ajv.compile(schema);
+
+  return validator(target, (data, c) => {
+    const valid = validate(data);
+    if (valid) {
+      if (hook) {
+        const hookResult = hook({ success: true, data: data as T }, c);
+        if (hookResult instanceof Response || hookResult instanceof Promise) {
+          return hookResult;
+        }
+      }
+      return data as T;
+    }
+
+    const errors = validate.errors || [];
+    if (hook) {
+      const hookResult = hook({ success: false, errors }, c);
+      if (hookResult instanceof Response || hookResult instanceof Promise) {
+        return hookResult;
+      }
+    }
+    return c.json({ success: false, errors }, 400);
+  });
+}