Mongoose: Is not a function ERROR - this.isModified is not a function

Created on 18 Sep 2016 · 11Comments · Source: Automattic/mongoose

When I use following code:

userSchema.pre('save', (done) => {
  if(this.isModified('password')) {
    bcrypt.hash(this.password, null, null, (err, hash) => {
      if(err) return next(err);

      this.password = hash;
      this.updated_at = new Date().toISOString();
      done();
    });
  } else {
    return done();
  }
});

I receive following Error:

TypeError: this.isModified is not a function
    at model.userSchema.pre (C:\code\project\core\models\user.js:26:11)
    at _next (C:\code\project\node_modules\hooks-fixed\hooks.js:62:30)
    at fnWrapper (C:\code\project\node_modules\hooks-fixed\hooks.js:186:8)
    at model.Object.defineProperty.value.fn (C:\code\project\node_modules\mongoose\lib\schema.js:221:11)
    at _next (C:\code\project\node_modules\hooks-fixed\hooks.js:62:30)
    at fnWrapper (C:\code\project\node_modules\hooks-fixed\hooks.js:186:8)
    at C:\code\project\node_modules\mongoose\lib\schema.js:196:17
    at C:\code\project\node_modules\kareem\index.js:127:16
    at _combinedTickCallback (internal/process/next_tick.js:67:7)
    at process._tickCallback (internal/process/next_tick.js:98:9)

Problem:

this is not a Document, Query or Schema. It's value is {}

How can I solve that?

Source

ghost

👍13

Most helpful comment

You are using an arrow operator for the callback, which changes the scope of this. If you define a regular callback you should be fine, e.g.:

userSchema.pre('save',  function(done)  {
});

VictorGerritsenQLVR on 20 Sep 2016

👍44 🎉14 😄11

All 11 comments

You are using an arrow operator for the callback, which changes the scope of this. If you define a regular callback you should be fine, e.g.:

userSchema.pre('save',  function(done)  {
});

VictorGerritsenQLVR on 20 Sep 2016

👍44 🎉14 😄11

Ok. Thanks. It works.

ghost on 20 Sep 2016

Fix your eslintrc

On Tue, Nov 29, 2016 at 5:16 AM, Nick Rameau notifications@github.com
wrote:

Is there a way to do it with arrow functions? I'm using ES6 and my
eslintrc is complaining about regular callbacks.

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vkarpov15 on 3 Dec 2016

I had this issue, as well. Thanks for help @VictorGerritsenQLVR!

codingleo on 15 Jan 2017

Is there a way to change the code to accommodate the arrow operator, rather than using function(next)?

domarp-j on 3 Apr 2017

@domarp-j Good question. I thought about it and tried to figure it out but I couldn't come up with anything easier than just switching to a regular callback function. Maybe someone else has done it tho. I'll keep an eye on this issue.