error handler middleware

Author: patrick-carmo

package-lock.json

@@ -15,6 +15,7 @@
         "dotenv": "^16.4.5",
         "env-var": "^7.4.1",
         "express": "^4.19.2",
+        "express-async-errors": "^3.1.1",
         "joi": "^17.12.2",
         "knex": "^3.1.0",
         "pg": "^8.11.3",

package.json

@@ -1,36 +1,25 @@
 import { Request, Response } from "express";
 import { currencyService } from "../services/currencyService";
 import { Conversion, Currency } from "../types/currency";
+import { BadRequestError } from "../utils/apiError";
 
 const listCurrencies = async (_: Request, res: Response) => {
-    try {
-        const currencies = await currencyService.getCurrencies();
-
-        return res.status(200).json(currencies);
-    } catch (error: any) {
-        return res.status(500).json({ message: error.message });
-    }
+    const currencies = await currencyService.getCurrencies();
+    return res.status(200).json(currencies);
 };
 
 const getCurrency = async (req: Request, res: Response) => {
     const code = (req.params.code as string).toUpperCase();
 
-    try {
-        const supportedCurrencies =
-            await currencyService.getSupportedCurrencies();
+    const supportedCurrencies = await currencyService.getSupportedCurrencies();
 
-        if (!supportedCurrencies.includes(code)) {
-            return res
-                .status(400)
-                .json({ message: "The currency is not supported" });
-        }
+    if (!supportedCurrencies.includes(code)) {
+        throw new BadRequestError("The currency is not supported");
+    }
 
-        const currency = await currencyService.getCurrency(code);
+    const currency = await currencyService.getCurrency(code);
 
-        return res.status(200).json(currency);
-    } catch (error: any) {
-        return res.status(500).json({ message: error.message });
-    }
+    return res.status(200).json(currency);
 };
 
 const convertCurrency = async (req: Request, res: Response) => {
@@ -43,36 +32,29 @@ const convertCurrency = async (req: Request, res: Response) => {
     const uppercaseFrom = from.toUpperCase();
     const uppercaseTo = to.toUpperCase();
 
-    try {
-        const supportedCurrencies =
-            await currencyService.getSupportedCurrencies();
-
-        if (!supportedCurrencies.includes(uppercaseFrom)) {
-            return res
-                .status(400)
-                .json({ message: "The currency from is not supported" });
-        }
-
-        if (!supportedCurrencies.includes(uppercaseTo)) {
-            return res
-                .status(400)
-                .json({ message: "The currency to is not supported" });
-        }
-
-        const data: Conversion = {
-            from: uppercaseFrom,
-            to: uppercaseTo,
-            amount,
-        };
-
-        const conversion: Conversion = await currencyService.getConversion(
-            data
+    const supportedCurrencies = await currencyService.getSupportedCurrencies();
+
+    if (!supportedCurrencies.includes(uppercaseFrom)) {
+        throw new BadRequestError(
+            `The currency ${uppercaseFrom} is not supported`
         );
+    }
 
-        return res.status(200).json(conversion);
-    } catch (error: any) {
-        return res.status(500).json({ message: error.message });
+    if (!supportedCurrencies.includes(uppercaseTo)) {
+        throw new BadRequestError(
+            `The currency ${uppercaseTo} is not supported`
+        );
     }
+
+    const data: Conversion = {
+        from: uppercaseFrom,
+        to: uppercaseTo,
+        amount,
+    };
+
+    const conversion: Conversion = await currencyService.getConversion(data);
+
+    return res.status(200).json(conversion);
 };
 
 const createCurrency = async (req: Request, res: Response) => {
@@ -84,13 +66,8 @@ const createCurrency = async (req: Request, res: Response) => {
         value,
     };
 
-    try {
-        await currencyService.createCurrency(currency);
-
-        return res.status(201).json(currency);
-    } catch (error: any) {
-        return res.status(500).json({ message: error.message });
-    }
+    await currencyService.createCurrency(currency);
+    return res.status(201).json(currency);
 };
 
 const updateCurrency = async (req: Request, res: Response) => {
@@ -103,25 +80,15 @@ const updateCurrency = async (req: Request, res: Response) => {
         value,
     };
 
-    try {
-        await currencyService.updateCurrency(codeParams, currency);
-
-        return res.status(204).send();
-    } catch (error: any) {
-        return res.status(500).json({ message: error.message });
-    }
+    await currencyService.updateCurrency(codeParams, currency);
+    return res.status(204).send();
 };
 
 const deleteCurrency = async (req: Request, res: Response) => {
     const code = (req.params.code as string).toUpperCase();
 
-    try {
-        await currencyService.deleteCurrency(code);
-
-        return res.status(204).send();
-    } catch (error: any) {
-        return res.status(500).json({ message: error.message });
-    }
+    await currencyService.deleteCurrency(code);
+    return res.status(204).send();
 };
 
 export const currencyController = {

src/controllers/currencyController.ts

@@ -1,16 +1,18 @@
 import "dotenv/config";
+import 'express-async-errors'
 import env from "./config/envConfig";
 import express from "express";
 import redis from "./database/redis";
 
 import currencyRoutes from "./routes/currencyRoute";
+import errorMiddleware from "./middlewares/error";
 
 redis.connect();
-
 const app = express();
 
 app.use(express.json());
 
 app.use(currencyRoutes);
+app.use(errorMiddleware)
 
 app.listen(env.PORT, () => console.log(`Server running on port ${env.PORT}`));

src/index.ts

@@ -0,0 +1,13 @@
+import { Request, Response, NextFunction } from "express";
+import { ApiError } from "../utils/apiError";
+
+export default function errorMiddleware(
+    error: Error & Partial<ApiError>,
+    req: Request,
+    res: Response,
+    next: NextFunction
+) {
+    const statusCode = error.statusCode ?? 500;
+    const message = statusCode !== 500 ? error.message : "Internal server error";
+    res.status(statusCode).json({ message });
+}

src/middlewares/error.ts

@@ -1,5 +1,6 @@
 import { Request, Response, NextFunction } from "express";
 import { ObjectSchema } from "joi";
+import { BadRequestError } from "../utils/apiError";
 
 const requestValidation =
     (schema: ObjectSchema) =>
@@ -8,26 +9,20 @@ const requestValidation =
         const params = Object.keys(req.params).length;
         const query = Object.keys(req.query).length;
         if (req.method !== "GET" && !body && !params && !query) {
-            return res
-                .status(400)
-                .json({ message: "Please fill out all the fields" });
+            throw new BadRequestError("Please fill out all the fields");
         }
 
-        try {
-            if (body) {
-                await schema.validateAsync({ body: req.body });
-            }
-            if (params) {
-                await schema.validateAsync({ params: req.params });
-            }
-            if (query) {
-                await schema.validateAsync({ query: req.query });
-            }
-
-            return next();
-        } catch (error: any) {
-            return res.status(400).json({ message: error.message });
+        if (body) {
+            await schema.validateAsync({ body: req.body });
+        }
+        if (params) {
+            await schema.validateAsync({ params: req.params });
         }
+        if (query) {
+            await schema.validateAsync({ query: req.query });
+        }
+
+        return next();
     };
 
 export default requestValidation;

src/middlewares/requestValidation.ts

@@ -2,7 +2,6 @@ import { Router } from "express";
 import { currencyController } from "../controllers/currencyController";
 import joi from "../middlewares/requestValidation";
 import { schema } from "../models/joiCurrency";
-import redis from "../database/redis";
 
 const route = Router();