Mongoose: Cannot add a virtual getter or setter to a schema, Object #<Object> has no method 'get'

[eytanbiala]

I'm using version 3.8.19.

Code:

var UserSchema = new mongoose.Schema({
   username: {
      type: String,
   }
});
UserSchema.virtual('username').get(function() {
    return this.username;
}).set(function(username) {
    this.usernameLower = username.toLowerCase();
});

Error:

/project/node_modules/mongoose/node_modules/mongodb/lib/mongodb/db.js:296
          throw err;
                ^
TypeError: Object #<Object> has no method 'get'
    at Object.<anonymous> (/project/models/user.js:115:32)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)

[k10der]

Hello!
I think that you can't assign a getter, because first you defininig a real property in your schema and then trying to redeclare it as a virtual.
So the solution is to change either a name of a virtual property or an object's property.

var UserSchema = new mongoose.Schema({
   username: {
      type: String,
   }
});
UserSchema.virtual('usernameLower').get(function() {
    return this.username.toLowerCase();
}).set(function(usernameLower) {
    this.username = usernameLower;
});

or

var UserSchema = new mongoose.Schema({
   usernameLower: {
      type: String,
   }
});
UserSchema.virtual('username').get(function() {
    return this.usernameLower;
}).set(function(username) {
    this.usernameLower = username.toLowerCase();
});

[vkarpov15]

@k10der is correct

[eytanbiala]

What is the correct way to override a setter or getter with mongoose, and to make sure that method is used?

[k10der]

Hi, eytanbiala.
If you need a custom getter(setter) for your schema field, you need just need to define a getter(setter) function for the path:
http://mongoosejs.com/docs/api.html#schematype_SchemaType-get
http://mongoosejs.com/docs/api.html#schematype_SchemaType-set

For example:

var UserSchema = new mongoose.Schema({
   username: {
      type: String,
   }
});
UserSchema.path('username')
    .get(function(value) {
        return value;
    })
    .set(function(value) {
    return value.toLowerCase();
});

[eytanbiala]

Thanks!

[henriquecustodia]

Thank you @k10der, great answer!

[polyclick]

Would be great if @k10der's answer was in the docs here: http://mongoosejs.com/docs/guide.html
I had the same problem. I wanted to update a date when a specific field in my schema changed. Made the same mistake by making a virtual that had the same name as the schema property.