chore: logs for express body parser (#577)

.changeset/shy-hounds-train.md

@@ -0,0 +1,8 @@
+---
+"uploadthing": patch
+---
+
+chore(express): add logs for express body parser
+
+Enables easier debugging for a common issue Express users has had when registed other middlewares before UploadThing that processes the body in an incompatible way.
+These logs should help track down these cases more easily

packages/uploadthing/src/express.ts

@@ -15,7 +15,7 @@ import {
   buildRequestHandler,
 } from "./internal/handler";
 import { incompatibleNodeGuard } from "./internal/incompat-node-guard";
-import { initLogger } from "./internal/logger";
+import { initLogger, logger } from "./internal/logger";
 import { getPostBody } from "./internal/node-http/getBody";
 import { toWebRequest } from "./internal/node-http/toWebRequest";
 import type { FileRouter } from "./internal/types";
@@ -47,6 +47,9 @@ export const createRouteHandler = <TRouter extends FileRouter>(
     const bodyResult = await getPostBody({ req });
 
     if (!bodyResult.ok) {
+      logger.error(
+        "Error parsing body. UploadThing expects a raw JSON body, make sure any body-parsing middlewares are registered after uploadthing.",
+      );
       res.status(400);
       res.setHeader("x-uploadthing-version", UPLOADTHING_VERSION);
       res.send(

packages/uploadthing/src/internal/node-http/getBody.ts

@@ -2,6 +2,8 @@ import type { IncomingMessage } from "node:http";
 
 import { UploadThingError } from "@uploadthing/shared";
 
+import { logger } from "../logger";
+
 export type BodyResult =
   | {
       ok: true;
@@ -18,9 +20,10 @@ export async function getPostBody(opts: {
   const { req, maxBodySize = Infinity } = opts;
   return new Promise((resolve) => {
     if ("body" in req) {
-      const isJsonType = req.headers["content-type"] === "application/json";
+      const contentType = req.headers["content-type"];
 
-      if (!isJsonType) {
+      if (contentType !== "application/json") {
+        logger.error("Expected JSON content type, got:", contentType);
         resolve({
           ok: false,
           error: new UploadThingError({
@@ -32,6 +35,10 @@ export async function getPostBody(opts: {
       }
 
       if (typeof req.body !== "object") {
+        logger.error(
+          "Expected body to be of type 'object', got:",
+          typeof req.body,
+        );
         resolve({
           ok: false,
           error: new UploadThingError({
@@ -42,6 +49,7 @@ export async function getPostBody(opts: {
         return;
       }
 
+      logger.debug("Body parsed successfully.", req.body);
       resolve({
         ok: true,
         data: req.body,
@@ -54,6 +62,13 @@ export async function getPostBody(opts: {
       body += data;
       hasBody = true;
       if (body.length > maxBodySize) {
+        logger.error(
+          "Body too large, max size is",
+          maxBodySize,
+          "bytes but received",
+          body.length,
+          "bytes",
+        );
         resolve({
           ok: false,
           error: new UploadThingError({
@@ -67,18 +82,22 @@ export async function getPostBody(opts: {
     req.on("end", () => {
       let parsedBody: unknown;
       try {
+        logger.debug("Finished reading body, parsing as JSON", body);
         parsedBody = JSON.parse(body);
       } catch (e) {
+        logger.error("Error parsing JSON:", body);
         resolve({
           ok: false,
           error: new UploadThingError({
             code: "BAD_REQUEST",
             message: "INVALID_JSON",
+            cause: e,
           }),
         });
         return;
       }
 
+      logger.debug("Body parsed successfully.", parsedBody);
       resolve({
         ok: true,
         data: hasBody ? parsedBody : undefined,