Adding Methods Mongoose Schema w/NestJS

Question

I need a transformation method attached to my Schema type. How can I accomplished with without duplicating code? If I remove the class methodasGrpcProgram I get the following error:

src/programs/programs.controller.ts:129:30 - error TS2339: Property 'asGrpcProgram' does not exist on type 'Program'.

If I remove the function expression assigned to ProgramSchema.methods.asGrpcProgram I get the following error when the method is invoked at runtime:

ERROR [RpcExceptionsHandler] program.asGrpcProgram is not a function

import { grpc } from 'lis-protobuf';
import { Document } from 'mongoose';

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

@Schema()
export class Program extends Document {
  @Prop({ required: true })
  name: string;

  @Prop()
  externalId: string;

  @Prop([String])
  skillIds: string[];

  public asGrpcProgram(): grpc.Program {
    const { id, name, externalId, skillIds } = this;
    return { id, name, externalId, skillIds };
  }
}

export const ProgramSchema = SchemaFactory.createForClass(Program);

ProgramSchema.methods.asGrpcProgram = function (): grpc.Program {
  const { id, name, externalId, skillIds } = this;
  return { id, name, externalId, skillIds };
};

score 2 · Answer 1 · answered Dec 29 '21 at 18:50

As is said here, you can just:

import { grpc } from 'lis-protobuf';
import { Document } from 'mongoose';

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

@Schema()
export class Program extends Document {
  @Prop({ required: true })
  name: string;

  @Prop()
  externalId: string;

  @Prop([String])
  skillIds: string[];

  asGrpcProgram: Function;
}

export const ProgramSchema = SchemaFactory.createForClass(Program);

ProgramSchema.methods.asGrpcProgram = function (): grpc.Program {
  const { id, name, externalId, skillIds } = this;
  return { id, name, externalId, skillIds };
};

Note: If the error persists after the above approach, try this one.

Adding Methods Mongoose Schema w/NestJS

1 Answers1