Error handling in Node.js can be done using try-catch blocks, which allow you to handle exceptions thrown by your code.
However, this approach can become repetitive and verbose when dealing with multiple error-prone functions. To avoid this, you can wrap these functions in a generic error-handling function (a "wrapper function") that takes care of catching any errors and handling them in a centralized way.
For example, you could define a wrapper function that receives a function as a parameter and returns a new function that automatically handles errors:
const wrap = (fn) => (req, res, next) =>
fn(req, res, next).catch(next);
With this wrapper function, you can simplify your error handling code by simply wrapping your route handlers:
app.post("/shoot", wrap(async (req, res) => {
const data = await doSomething();
res.send(data);
}));
Let's work with a better example.
Old code
exports.getAllTrips = async (req, res, next) => {
try {
const { id } = req.user;
console.log(id);
const trips = await Trip.find({ userId: id })
.sort({ createdAt: -1 });
if (!trips) return errorResMsg(res, 404, "No trips found");
const dataInfo = {
message: "Trips found",
trips,
};
return successResMsg(res, 200, dataInfo);
} catch (error) {
next(error);
}
};
New Code
First we create wrapper function
// handle callback
const handleCallback = (callback) => {
return async (req, res, next) => {
try {
await callback(req, res, next);
} catch (error) {
next(error);
}
};
};
Then use the handleCallback to wrap the route
exports.getAllTrips = handleCallback(async (req, res) => {
const { id } = req.user;
const trips = await Trip.find({ userId: id }).sort({ createdAt: -1 });
if (!trips) return errorResMsg(res, 404, "No trips found");
const dataInfo = {
message: "Trips found",
trips,
};
return successResMsg(res, 200, dataInfo);
});
Conclusion
Wrapper function can be utilized to streamline the try/catch block and promote DRY (Don't Repeat Yourself) principles in coding.
Top comments (9)
If you want to handle error in express routes, you don't need to wrap the controller with a wrapper function, just use express-async-errors and create error middleware handling for handling errors.
Look to the docs for know how to use it
I have used this package too. Thanks for the contribution
This was very helpful sir...
So with just that one handleCallBack function it can be applied to all the routes?
Yes, you will just follow the same syntax as shown in the getAllTrips controller function
@abhaysinghr1 Thanks for the comment
Great post. Makes a cleaner code.
Thanks @wilmela. Glad it was helpful
I already use this, thanks very useful! Just thinking.. Can we add some kind of middle-ware code? Like how express-async-error solves it? Since we still need to repeat ourselves now on each API end-point.