Kevin Powell - Community•17mo ago

Issue with throwing error

there is something confusing here in express how i got 200 response in the both cases if i find a book or not this is the error handler middleware

const errorhandler = (err, req, res, next) => {
    console.log(res.statusCode);
    const statusCode = res.statusCode ? res.statusCode : 500; 

    switch (statusCode) {
        case 400:
            return res.status(400).json({
                title: "Validation failed",
                message: err.message,
                stackTrace: err.stack,
            });
        case 401:
            return res.status(401).json({
                title: "Not Authorized",
                message: err.message,
                stackTrace: err.stack,
            });
        case 403:
            return res.status(403).json({
                title: "Forbidden",
                message: err.message,
                stackTrace: err.stack,
            });
        case 404:
            return res.status(404).json({
                title: "Not Found",
                message: err.message,
                stackTrace: err.stack,
            });
        default:
            console.log("No errors");
            break;
    }
    res.json();
};

module.exports = errorhandler;

const errorhandler = (err, req, res, next) => {
    console.log(res.statusCode);
    const statusCode = res.statusCode ? res.statusCode : 500; 

    switch (statusCode) {
        case 400:
            return res.status(400).json({
                title: "Validation failed",
                message: err.message,
                stackTrace: err.stack,
            });
        case 401:
            return res.status(401).json({
                title: "Not Authorized",
                message: err.message,
                stackTrace: err.stack,
            });
        case 403:
            return res.status(403).json({
                title: "Forbidden",
                message: err.message,
                stackTrace: err.stack,
            });
        case 404:
            return res.status(404).json({
                title: "Not Found",
                message: err.message,
                stackTrace: err.stack,
            });
        default:
            console.log("No errors");
            break;
    }
    res.json();
};

module.exports = errorhandler;

and this is the function

const updateBook = asyncHandler(async (req, res) => {
    const book = await Books.findById(req.params.bookId);
    if (!book) {
        res.status(404); // Set the response status to 404
        throw new Error("Book not found");
    } else {
        res.status(200).json(book);
    }
});

const updateBook = asyncHandler(async (req, res) => {
    const book = await Books.findById(req.params.bookId);
    if (!book) {
        res.status(404); // Set the response status to 404
        throw new Error("Book not found");
    } else {
        res.status(200).json(book);
    }
});

34 Replies

Jochem•17mo ago

I'm not super familiar with express or its middleware, but

 const statusCode = res.statusCode ? res.statusCode : 500;

 const statusCode = res.statusCode ? res.statusCode : 500;

Are you sure you want to use res.statusCode? https://expressjs.com/en/4x/api.html#res This seems to suggest res doesn't have a statusCode property that would mean the statusCode variable would be 500, which is a case you're not handling (also, you can write that as const statusCode = res.statusCode ?? 500; instead of having res.statusCode twice) hm, wait, it does log out the 200 doesn't it. Maybe Books.findById is returning something truthy even if it doesn't find anything? What ORM are you using?

MuhammedAlaaOP•17mo ago

yep that what i was going to tell you that it logs out 200 when it goes to the error handler im using mongoose

Jochem•17mo ago

seems like you need to call exec() on findById https://mongoosejs.com/docs/api/model.html#Model.findById()

await Adventure.findById(id).exec();

await Adventure.findById(id).exec();

which would return null, which is falsey, so it should work as expected

MuhammedAlaaOP•17mo ago

same issue i tried to log the result from the findById it doesn't log any thing if not found

MuhammedAlaaOP•17mo ago

const updateBook = asyncHandler(async (req, res) => {
    const book = await Books.findById(req.params.bookId).exec();
    console.log(book);
    if (!book) {
        res.status(404); // Set the response status to 404
        throw new Error("Book not found");
    } else {
        res.status(200).json(book);
    }
});

const updateBook = asyncHandler(async (req, res) => {
    const book = await Books.findById(req.params.bookId).exec();
    console.log(book);
    if (!book) {
        res.status(404); // Set the response status to 404
        throw new Error("Book not found");
    } else {
        res.status(200).json(book);
    }
});

Jochem•17mo ago

can you change it to console.log(typeof book);?

MuhammedAlaaOP•17mo ago

if found => object not found doesn't log anything

Jochem•17mo ago

that is very strange, even if it is returning null it should still log out something, in both situations btw with the ID that should 404, is it still matching with this route?

MuhammedAlaaOP•17mo ago

but it goes inside the if because if it didn't then it will not log the res.statusCode

Jochem•17mo ago

that's in the middleware though

MuhammedAlaaOP•17mo ago

idk how it goes inside the if and still response with 200

Jochem•17mo ago

it looks like the 404 isn't hitting updateBook at all, otherwise you'd see the log and have an error thrown, I see none of those in the console add a console.log above findById that just logs out something like "in updateBook"

MuhammedAlaaOP•17mo ago

Jochem•17mo ago

hm, that is very strange I'm honestly not sure what's causing that then

MuhammedAlaaOP•17mo ago

np appreciate your help i will try to figure it out or look for a tutorial doing the same thing

Jochem•17mo ago

Hopefully someone else will come along that does know 🙂 good luck!

MuhammedAlaaOP•17mo ago

i tried to put my code in a try catch block and it worked fine idk why i can't figure out

const updateBook = asyncHandler(async (req, res) => {
    try {
        const book = await Books.findById(req.params.bookId);
        console.log(book);
        res.status(200).json(book);
    } catch (error) {
        console.log(error);
        res.status(404); // Set the response status to 404
        throw new Error("Book not found");
    }
});

const updateBook = asyncHandler(async (req, res) => {
    try {
        const book = await Books.findById(req.params.bookId);
        console.log(book);
        res.status(200).json(book);
    } catch (error) {
        console.log(error);
        res.status(404); // Set the response status to 404
        throw new Error("Book not found");
    }
});

Jochem•17mo ago

hm, the docs for mongoose claim it just returns null when it can't find the book, but I guess it's throwing after all good to know you found a solution though!

MuhammedAlaaOP•17mo ago

yep im just wondering how , i found a tutorial doing what i did exactly and works fine maybe something is new in moongose idk

Jochem•17mo ago

yeah, could be a version issue

MuhammedAlaaOP•17mo ago

yep, any ways thanks for your time ❤️

ErickO•17mo ago

haha, timezones I would've told you this right away cause been there done that always been that way, if you look for 1 thing and it's not there it throws

Jochem•17mo ago

stupid, lying docs 😄

ErickO•17mo ago

only time when it doesn't throw is if you look for more than one thing findMany and it's not there because ofc it does consistency

Jochem•17mo ago

another good reason I usually prefer just a DB driver over a ORM

ErickO•17mo ago

haha funny you should mention that that's just mongo same thing happens in Go so I'm guessing is how mongo works so...another good reason to not use mongo 😎

Jochem•17mo ago

haha, well, nice to see I can just move the column over without changing its header ;D

ErickO•17mo ago

reason why I hate this so much is that now you have to consider the error if you want to do something specific in each case, because sure any error you can send a 404 but it isn't always a not found error...so if you wanted to show different messages you now have to check what error it is to send either a 404 or a 500

MuhammedAlaaOP•17mo ago

ok i got u but still can't know why it doesn't log book when its not found ?

Jochem•17mo ago

because throwing an error stops code execution in the current context

MuhammedAlaaOP•17mo ago

hmm, but the log was before even checking if there is book or not ok maybe because asynchandler of express resolve the await directly and throw the error ?

Jochem•17mo ago

hm, I'm not sure

MuhammedAlaaOP•17mo ago

https://www.npmjs.com/package/express-async-handler i think because it take a look here

npm

express-async-handler

Express Error Handler for Async Functions. Latest version: 1.2.0, last published: 2 years ago. Start using express-async-handler in your project by running npm i express-async-handler. There are 201 other projects in the npm registry using express-async-handler.

MuhammedAlaaOP•17mo ago

asyncHandler catches the error automatically i think because of this it doesn't log

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Issue with throwing error