Create mongoose schema methods using TypeScript

Question

I try to create method hashPassword for user schema.

schema.method("hashPassword", function (): void {
  const salt = bcrypt.genSaltSync(10);
  const hash = bcrypt.hashSync(this.password, salt);

  this.password = hash;
});

And get an error Property 'password' does not exist on type 'Document<any>'. on password

Here is my file

import mongoose, { Schema, Document } from "mongoose";
import bcrypt from "bcryptjs";

/**
 * This interface should be the same as JWTPayload declared in types/global.d.ts file
 */
export interface IUser extends Document {
  name: string;
  email: string;
  username: string;
  password: string;
  confirmed: boolean;
  hashPassword: () => void;
  checkPassword: (password: string) => boolean;
}

// User schema
const schema = new Schema(
  {
    name: {
      type: String,
      required: true,
    },
    email: {
      type: String,
      required: true,
    },
    username: {
      type: String,
      required: true,
    },
    password: {
      type: String,
      required: true,
    },
    confirmed: {
      type: Boolean,
      default: false,
    },
  },
  { timestamps: true }
);

schema.method("hashPassword", function (): void {
  const salt = bcrypt.genSaltSync(10);
  const hash = bcrypt.hashSync(this.password, salt);

  this.password = hash;
});

// User model
export const User = mongoose.model<IUser>("User", schema, "users");

Answer 1

At the point where you define the method, the schema object doesn't know that it is the Schema for an IUser and not just any Document. You need to set the generic type for the Schema when you create it: new Schema<IUser>( ... ).