feat: add middleware

README.md

@@ -202,6 +202,68 @@ json-server -s ./static
 json-server -s ./static -s ./node_modules
 ```
 
+## Middleware
+
+```sh
+json-server --middleware logger.mjs
+```
+
+```js
+// logger.mjs
+import chalk from 'chalk';
+
+export default (req, _res, next) => {
+  const currentDate = new Date().toISOString();
+  console.log(chalk.green(req.method), chalk.yellow(req.url), chalk.blue(`${currentDate}`));
+
+  // Check if the request body is already parsed
+  if (req.body && Object.keys(req.body).length > 0) {
+    console.log(chalk.magenta('Body:'), req.body);
+  } else {
+    // Manually parse the request body if not already parsed
+    let body = '';
+    req.on('data', (chunk) => {
+      body += chunk.toString();
+    });
+    req.on('end', () => {
+      if (body) {
+        try {
+          const parsedBody = JSON.parse(body);
+          console.log(chalk.magenta('Body:'), parsedBody);
+        } catch (error) {
+          console.log(chalk.red('Failed to parse body'), error);
+        }
+      }
+      next();
+    });
+    return;
+  }
+
+  next();
+};
+```
+
+This will output:
+
+```sh
+Index:
+http://localhost:3000/
+
+Static files:
+Serving ./public directory if it exists
+
+Endpoints:
+http://localhost:3000/posts
+http://localhost:3000/comments
+http://localhost:3000/profile
+
+PATCH /posts/1 2025-01-03T08:25:13.138Z
+Body: { title: 'foo', body: 'bar', userId: 1 }
+POST /posts 2025-01-03T08:25:18.661Z
+Body: { title: 'foo', body: 'bar', userId: 1 }
+GET /posts 2025-01-03T08:25:20.159Z
+```
+
 ## Notable differences with v0.17
 
 - `id` is always a string and will be generated for you if missing

middleware/logger.mjs

@@ -0,0 +1,31 @@
+import chalk from 'chalk';
+
+export default (req, _res, next) => {
+  const currentDate = new Date().toISOString();
+  console.log(chalk.green(req.method), chalk.yellow(req.url), chalk.blue(`${currentDate}`));
+
+  // Check if the request body is already parsed
+  if (req.body && Object.keys(req.body).length > 0) {
+    console.log(chalk.magenta('Body:'), req.body);
+  } else {
+    // Manually parse the request body if not already parsed
+    let body = '';
+    req.on('data', (chunk) => {
+      body += chunk.toString();
+    });
+    req.on('end', () => {
+      if (body) {
+        try {
+          const parsedBody = JSON.parse(body);
+          console.log(chalk.magenta('Body:'), parsedBody);
+        } catch (error) {
+          console.log(chalk.red('Failed to parse body'), error);
+        }
+      }
+      next();
+    });
+    return;
+  }
+
+  next();
+};

package.json

@@ -18,6 +18,7 @@
     "dev": "tsx watch src/bin.ts fixtures/db.json",
     "build": "rm -rf lib && tsc",
     "test": "node --import tsx/esm --test src/*.test.ts",
+    "logger": "tsx watch src/bin.ts fixtures/db.json --middleware=middleware/logger.mjs",
     "lint": "eslint src",
     "prepare": "husky",
     "prepublishOnly": "npm run build"
@@ -60,4 +61,4 @@
     "sirv": "^2.0.4",
     "sort-on": "^6.1.0"
   }
-}
+}

src/app.ts

@@ -16,6 +16,7 @@ const isProduction = process.env['NODE_ENV'] === 'production'
 export type AppOptions = {
   logger?: boolean
   static?: string[]
+  middleware?: (req: unknown, res: unknown, next: unknown) => void
 }
 
 const eta = new Eta({
@@ -36,6 +37,11 @@ export function createApp(db: Low<Data>, options: AppOptions = {}) {
     ?.map((path) => (isAbsolute(path) ? path : join(process.cwd(), path)))
     .forEach((dir) => app.use(sirv(dir, { dev: !isProduction })))
 
+  // Use middleware if specified
+  if (options.middleware) {
+    app.use(options.middleware)
+  }
+
   // CORS
   app
     .use((req, res, next) => {

src/bin.ts

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 import { existsSync, readFileSync, writeFileSync } from 'node:fs'
-import { extname } from 'node:path'
+import { extname, resolve } from 'node:path'
 import { parseArgs } from 'node:util'
 
 import chalk from 'chalk'
@@ -19,11 +19,12 @@ function help() {
   console.log(`Usage: json-server [options] <file>
 
 Options:
-  -p, --port <port>  Port (default: 3000)
-  -h, --host <host>  Host (default: localhost)
-  -s, --static <dir> Static files directory (multiple allowed)
-  --help             Show this message
-  --version          Show version number
+  -p, --port <port>        Port (default: 3000)
+  -h, --host <host>        Host (default: localhost)
+  -s, --static <dir>       Static files directory (multiple allowed)
+  --middleware <file>      Middleware file
+  --help                   Show this message
+  --version                Show version number
 `)
 }
 
@@ -33,6 +34,7 @@ function args(): {
   port: number
   host: string
   static: string[]
+  middleware: string
 } {
   try {
     const { values, positionals } = parseArgs({
@@ -53,6 +55,10 @@ function args(): {
           multiple: true,
           default: [],
         },
+        middleware: {
+          type: 'string',
+          default: '',
+        },
         help: {
           type: 'boolean',
         },
@@ -97,9 +103,10 @@ function args(): {
     // App args and options
     return {
       file: positionals[0] ?? '',
-      port: parseInt(values.port as string),
-      host: values.host as string,
-      static: values.static as string[],
+      port: parseInt(values.port),
+      host: values.host,
+      static: values.static,
+      middleware: values.middleware,
     }
   } catch (e) {
     if ((e as NodeJS.ErrnoException).code === 'ERR_PARSE_ARGS_UNKNOWN_OPTION') {
@@ -112,7 +119,19 @@ function args(): {
   }
 }
 
-const { file, port, host, static: staticArr } = args()
+// Load middleware
+async function loadMiddleware(middlewarePath: string) {
+  const resolvedPath = resolve(process.cwd(), middlewarePath)
+  if (existsSync(resolvedPath)) {
+    const middlewareModule = await import(resolvedPath)
+    return middlewareModule.default || middlewareModule
+  } else {
+    console.error(`Middleware file not found: ${resolvedPath}`)
+    process.exit(1)
+  }
+}
+
+const { file, port, host, static: staticArr, middleware } = args()
 
 if (!existsSync(file)) {
   console.log(chalk.red(`File ${file} not found`))
@@ -139,8 +158,19 @@ const observer = new Observer(adapter)
 const db = new Low<Data>(observer, {})
 await db.read()
 
+// Load middleware if specified
+let middlewareFunction
+if (middleware) {
+  console.log(chalk.gray(`Loading middleware from ${middleware}`))
+  middlewareFunction = await loadMiddleware(middleware)
+}
+
 // Create app
-const app = createApp(db, { logger: false, static: staticArr })
+const app = createApp(db, {
+  logger: false,
+  static: staticArr,
+  middleware: middlewareFunction,
+})
 
 function logRoutes(data: Data) {
   console.log(chalk.bold('Endpoints:'))
@@ -157,6 +187,7 @@ function logRoutes(data: Data) {
       )
       .join('\n'),
   )
+  console.log()
 }
 
 const kaomojis = ['♡⸜(˶˃ ᵕ ˂˶)⸝♡', '♡( ◡‿◡ )', '( ˶ˆ ᗜ ˆ˵ )', '(˶ᵔ ᵕ ᵔ˶)']

test.http

@@ -0,0 +1,22 @@
+###
+GET http://localhost:3000/posts
+
+###
+POST http://localhost:3000/posts
+Content-Type: application/json
+
+{
+  "title": "foo",
+  "body": "bar",
+  "userId": 1
+}
+
+###
+PATCH http://localhost:3000/posts/1
+Content-Type: application/json
+
+{
+  "title": "foo",
+  "body": "bar",
+  "userId": 1
+}