How to effectively manage Mongoose Query Exceptions in Express.js

Question

How to effectively manage Mongoose Query Exceptions in Express.js

Let's imagine a scenario where I need to execute a Mongoose query in an Express post route:

app.post("/login",(req,res)=>{
    const username = req.body.username
    const password = req.body.password
    User.find({username:username},(err,user)=>{
        if (err) handleError(err)
        //if user exists
        if (user.length) {
            //check password
            if (user.password === password) {
                //assign jwt, redirect
            } else {
                //"username/password is incorrect"
            }
        } else {
            //"username/password is incorrect"
        }
    })
})

I'm uncertain about the purpose of the handleError function. Since it involves a simple query in Mongoose, what kinds of errors could potentially occur and how should they be handled within the handleError function? Additionally, what type of response should I provide to the user in such cases?

javascript mongodb rest express mongoose

Answer 1

Answer №1

In my view, here is what you should do:

Consider implementing promises with async/await.
Avoid catching errors in your middleware and instead manage errors in the top-level express error handler. Further details can be found here.
In the top-level express error handler, choose the appropriate action based on the environment. For instance, for production, return a simple message like:
```
return res.status(500).json({ message: "Our server is currently inaccessible, please try again later." });
```
. In a local environment, send a JSON payload containing the error using:
```
return res.status(500).json({ err: <Error> });
```
.

To summarize, ensure your code resembles this structure:

app.post('/login', async (req, res) {
  
  // Utilize ES6 Destructuring
  const { username, password } = req.body;

  // Opt for findOne over find for faster query execution
  const user = await User.findOne({ username });

  if (!user || (user.password !== hashFunction(password))) {
    return res.status(403).json({ message: 'Invalid credentials' });
  }

  // Generate JWT token and redirect
});

Answer 2

In my view, here is what you should do:

Consider implementing promises with async/await.
Avoid catching errors in your middleware and instead manage errors in the top-level express error handler. Further details can be found here.
In the top-level express error handler, choose the appropriate action based on the environment. For instance, for production, return a simple message like:
```
return res.status(500).json({ message: "Our server is currently inaccessible, please try again later." });
```
. In a local environment, send a JSON payload containing the error using:
```
return res.status(500).json({ err: <Error> });
```
.

To summarize, ensure your code resembles this structure:

app.post('/login', async (req, res) {
  
  // Utilize ES6 Destructuring
  const { username, password } = req.body;

  // Opt for findOne over find for faster query execution
  const user = await User.findOne({ username });

  if (!user || (user.password !== hashFunction(password))) {
    return res.status(403).json({ message: 'Invalid credentials' });
  }

  // Generate JWT token and redirect
});

Answer 3

Answer №2

To handle Mongoose response, it is recommended to send an error message in your response.

app.post("/login",(req,res)=>{
    const userName = req.body.userName
    const password = req.body.password
    User.findOne({userName:userName},(error,user)=>{
        if (error){
          return res.status(400).json({message:"Error finding user.", error: error });
        }
        //if user exists
        if (user) {
            //check password
            if (user.password === password) {
                //generate jwt token, redirect
            } else {
                //respond with "Invalid username or password"
            }
        } else {
            //respond with "Invalid username or password"
        }
    })
})

Answer 4

To handle Mongoose response, it is recommended to send an error message in your response.

app.post("/login",(req,res)=>{
    const userName = req.body.userName
    const password = req.body.password
    User.findOne({userName:userName},(error,user)=>{
        if (error){
          return res.status(400).json({message:"Error finding user.", error: error });
        }
        //if user exists
        if (user) {
            //check password
            if (user.password === password) {
                //generate jwt token, redirect
            } else {
                //respond with "Invalid username or password"
            }
        } else {
            //respond with "Invalid username or password"
        }
    })
})

How to effectively manage Mongoose Query Exceptions in Express.js

Answer №1

Answer №2

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