How to define mongoose method in schema class with using nestjs/mongoose?

Question

I want to implement method in schema class like below.

import { SchemaFactory, Schema, Prop } from '@nestjs/mongoose';
import { Document } from 'mongoose';
import bcrypt from 'bcrypt';

@Schema()
export class Auth extends Document {
  @Prop({ required: true, unique: true })
  username: string;

  @Prop({ required: true })
  password: string;

  @Prop({
    methods: Function,
  })
  async validatePassword(password: string): Promise<boolean> {
    return bcrypt.compareAsync(password, this.password);
  }
}
export const AuthSchema = SchemaFactory.createForClass(Auth);

this schema return undefined when log the method . How can I write method in class schema with nestjs/mongoose package?

That would be instance methods. Are you looking for static methods? — Chau Tran, Jun 10 '20 at 15:15
No i'm looking for instance methods. I can't define it inside class — Sajjad Hadafi, Jun 11 '20 at 06:08
The Schema will definitely return `undefined` for `validatePassword` since it is an instance method which it is on the model, not the schema. — Chau Tran, Jun 11 '20 at 12:16
Ya,you say true but the point is how to write method on schema — Sajjad Hadafi, Jun 13 '20 at 08:29

score 29 · Accepted Answer · answered Oct 15 '20 at 18:55

29

You can use below approach to achieve this.

@Schema()
export class Auth extends Document {
    ...
    
    validatePassword: Function;
}

export const AuthSchema = SchemaFactory.createForClass(Auth);

AuthSchema.methods.validatePassword = async function (password: string): Promise<boolean> {
    return bcrypt.compareAsync(password, this.password);
};

answered Oct 15 '20 at 18:55

Suroor Ahmmad

1,110
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Hi, new to typed mongo in nestjs. Why cant we define these instance methods in the `@Schema` decorator with methods option. I tired this but it doesnt seem to work! Thanks for your solution, it works! Just wondering why its provided in the decorator and if you are aware of how to use it @Suroor Ahmmad – utsavojha95 Mar 15 '23 at 21:09
1

With the `@Schema()` decorator, you can only specify the schema and not define the method inside it. – Suroor Ahmmad Mar 17 '23 at 10:11
Ok thanks, just wondering why we can define an instance/methods object with functions in it in @Schema() decorator in @nestjs/mongoose. But yes it does not work I am wondering what is the use of this option that we can pass to the @Schema decorator. – utsavojha95 Mar 17 '23 at 22:07

score 0 · Answer 2 · answered Dec 30 '21 at 14:53

Use this function instead of SchemaFactory.createForClass(Auth):

export function createSchema(document: any) {
  const schema = SchemaFactory.createForClass(document);

  const instance = Object.create(document.prototype);

  for (const objName of Object.getOwnPropertyNames(document.prototype)) {
    if (
      objName != 'constructor' &&
      typeof document.prototype[objName] == 'function'
    ) {
      schema.methods[objName] = instance[objName];
    }
  }

  return schema;
}

How to define mongoose method in schema class with using nestjs/mongoose?

2 Answers2

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