feat: support the already parsed body

README.md

@@ -89,6 +89,16 @@ app.use((ctx) => {
   );
   ```
 
+- **enableRawChecking**: support the already parsed body on the raw request by override and prioritize the parsed value over the sended payload. (default is `false`)
+
+```js
+app.use(
+  bodyParser({
+    enableRawChecking: true,
+  })
+);
+```
+
 - **disableBodyParser**: you can dynamic disable body parser by set `ctx.disableBodyParser = true`.
 
   ```js

src/body-parser.ts

@@ -14,6 +14,12 @@ declare module 'koa' {
   }
 }
 
+declare module 'http' {
+  // eslint-disable-next-line @typescript-eslint/consistent-type-definitions
+  interface IncomingMessage {
+    body?: any;
+  }
+}
 /**
  * Middleware wrapper which delegate options to the core code
  */
@@ -23,6 +29,7 @@ export function bodyParserWrapper(opts: BodyParserOptions = {}) {
     onerror,
     enableTypes = ['json', 'form'],
     extendTypes = {} as NonNullable<BodyParserOptions['extendTypes']>,
+    enableRawChecking = false,
     ...restOpts
   } = opts;
   const isEnabledBodyAs = getIsEnabledBodyAs(enableTypes);
@@ -60,6 +67,13 @@ export function bodyParserWrapper(opts: BodyParserOptions = {}) {
 
   return async function (ctx: Koa.Context, next: Koa.Next) {
     if (ctx.request.body !== undefined || ctx.disableBodyParser) return next();
+    // raw request parsed and contain 'body' values and it's enabled to override the koa request
+    if (enableRawChecking && ctx.req.body !== undefined) {
+      // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
+      ctx.request.body = ctx.req.body;
+      return next();
+    }
+
     try {
       const response = await parseBody(ctx);
       ctx.request.body = 'parsed' in response ? response.parsed : {};

src/body-parser.types.ts

@@ -16,6 +16,10 @@ export type BodyParserOptions = {
    * error handler, can help to customize the response on error case
    */
   onerror?: (error: Error, ctx: Koa.Context) => void;
+  /**
+   *  False to disable the raw request body checking to prevent koa request override
+   */
+  enableRawChecking?: boolean;
   /**
    * co-body parser will only parse when request type hits enableTypes
    * @default ['json', 'form']

test/middleware.test.ts

@@ -6,8 +6,21 @@ import type { BodyParserOptions } from "../src/body-parser.types";
 import { UnsupportedBodyTypeError } from "../src/body-parser.utils";
 
 const fixtures = path.join(__dirname, "fixtures");
-const createApp = (options?: BodyParserOptions) => {
+type CreateAppConfig = BodyParserOptions & {
+  rawParsedBody?: Record<string, string>;
+};
+
+const createApp = (config: CreateAppConfig = {}) => {
+  const { rawParsedBody, ...options } = config;
   const app = new Koa();
+  rawParsedBody &&
+    app.use((ctx, next) => {
+      ctx.req.body = rawParsedBody;
+      console.log("==== middelware ====", rawParsedBody);
+
+      return next();
+    });
+
   app.use(bodyParser(options));
   return app;
 };
@@ -464,4 +477,33 @@ describe("test/body-parser.test.ts", () => {
         .expect("empty", done);
     });
   });
+
+  describe("enableRawChecking", () => {
+    it("should override koa request with raw request body if exist and enableRawChecking is truthy", (done) => {
+      const rawParsedBody = { rawFoo: "rawBar" };
+      const app = createApp({ rawParsedBody, enableRawChecking: true });
+      app.use(async (ctx) => {
+        ctx.body = ctx.request.body;
+      });
+
+      server = app.listen();
+      request(server)
+        .post("/")
+        .send({ foo: "bar" })
+        .expect(rawParsedBody, done);
+    });
+    it("shouldn't override koa request with raw request body if not exist and enableRawChecking is truthy", (done) => {
+      const rawParsedBody = undefined;
+      const app = createApp({ rawParsedBody, enableRawChecking: true });
+      app.use(async (ctx) => {
+        ctx.body = ctx.request.body;
+      });
+
+      server = app.listen();
+      request(server)
+        .post("/")
+        .send({ foo: "bar" })
+        .expect({ foo: "bar" }, done);
+    });
+  });
 });