🚧 WIP: Error Handling

Author: nabadeep25

src/app.ts

@@ -5,6 +5,7 @@ import cors from "cors";
 import { customRequest } from "./types/customDefinition";
 import { deserializeUser } from "./middleware";
 import appRouter from "./routes/v1";
+import { errorHandler } from "./middleware/error";
 
 // Create Express server
 const app = express();
@@ -50,5 +51,6 @@ app.patch("/api/sync", async (req, res) => {
     return res.status(400).json({ errorMsg: msg, error: true });
   }
 });
-
+// middleware to handle error
+app.use(errorHandler);
 export default app;

src/middleware/error.ts

@@ -0,0 +1,37 @@
+import { customError } from "customDefinition";
+import { NextFunction, Request, Response } from "express";
+import { ApiError } from "../util/ApiError";
+
+/**
+ * Error Handler Middleware
+ * @param error
+ * @param req
+ * @param res
+ * @param next
+ */
+export const errorHandler = (
+  error: customError,
+  req: Request,
+  res: Response,
+  // eslint-disable-next-line @typescript-eslint/no-unused-vars
+  next: NextFunction
+): void => {
+  let err = error;
+
+  if (!(error instanceof ApiError)) {
+    const statusCode = 500;
+    const message = error.message || "Internal server error";
+    err = new ApiError(statusCode, message);
+  }
+
+  const { statusCode, message } = err;
+
+  res.locals.errorMessage = err.message;
+
+  const response = {
+    code: statusCode,
+    message,
+  };
+
+  res.status(statusCode).send(response);
+};

src/types/customDefinition.ts

@@ -1,5 +1,15 @@
-import { Request } from "express";
+import { NextFunction, Request, Response } from "express";
 
 export interface customRequest extends Request {
   user: any;
 }
+
+export interface customError extends Error {
+  statusCode: number;
+}
+
+export type ControllerFunction = (
+  req: Request,
+  res: Response,
+  next: NextFunction
+) => void;

src/util/ApiError.ts

@@ -0,0 +1,8 @@
+export class ApiError extends Error {
+  statusCode: number;
+
+  constructor(statusCode: number, message: string) {
+    super(message);
+    this.statusCode = statusCode;
+  }
+}

src/util/handleError.ts

@@ -0,0 +1,8 @@
+import { ControllerFunction } from "customDefinition";
+import { NextFunction, Request, Response } from "express";
+
+export function handleError(fn: ControllerFunction) {
+  return (req: Request, res: Response, next: NextFunction): void => {
+    Promise.resolve(fn(req, res, next)).catch(err => next(err));
+  };
+}