如何修复Mongoose中findOneAndUpdate的FailedToParse错误？

Hey there, let's break down why your logout route is throwing that FailedToParse error (code 9) and fix it up.

The Root Cause #

The error message tells us MongoDB can't parse the update values you're sending. Looking at your code, the issue is with the tokenExp field: you're trying to set it to an empty string (""), but your schema defines tokenExp as a number type. MongoDB rejects this because it can't convert a string to a number automatically for this operation.

Your useFindAndModify: false configuration isn't the problem here—that setting just tells Mongoose to use MongoDB's native findOneAndUpdate instead of the older findAndModify method, which is totally fine.

The Fix #

You need to update tokenExp with a value that matches its number type. Here are two common options depending on your schema:

1. Use null (if your schema allows null values for tokenExp):
   Modify your update object to set tokenExp to null instead of an empty string:

   router.get("/logout", auth, (req, res) => { 
     console.log(req.user.email) 
     User.findOneAndUpdate(
       { email: req.user.email }, 
       { token: "", tokenExp: null },
       { new: true, useFindAndModify: false }, // Explicitly set the option for clarity
       (err, doc) => { 
         if (err) return res.json({ success: false, err }); 
         return res.status(200).send({ success: true }); 
       }
     ); 
   });
   

2. Use an invalid numeric value (like 0, if null isn't allowed):
   If your schema doesn't permit null for tokenExp, set it to a number that clearly indicates the token is expired (like 0):

   { token: "", tokenExp: 0 }
   

Double-Check Your Schema #

Make sure your User schema aligns with the value you choose. For example, if you want to use null, your schema should allow it:

const userSchema = new mongoose.Schema({
  // ... other fields
  token: String,
  tokenExp: {
    type: Number,
    allowNull: true, // Add this if you want to use null
    default: 0 // Optional default value
  }
});

That should resolve the FailedToParse error and let your logout endpoint correctly clear the token fields.

内容的提问来源于stack exchange，提问作者Jonathan G.