I’m fairly new to those stacks as I’m trying to use them to build an app (GraphQL, NestJS, and implementing with MongoDB).

I have a file for my Model, in which I export a custom Class and Type to use later on defined as such:

address.model.ts :

@ObjectType()
export class myAddress {
    @Field(type => Int, { nullable: true })
    id?: number;
    @Field()
    name: string;
    @Field()
    company: string;
    @Field()
    street1: string;
    @Field()
    street2: string;
    @Field()
    city: string;
    @Field()
    state: string;
    @Field()
    zip: string;
    @Field()
    country: string;
    @Field()
    email: string;
    @Field()
    phone: string;
    @Field()
    verify: string[];
    @Field()
    notes: string;

Following the docs in NestJS for GraphQL and Mongo integration, I created an input and dto file to, I believe, fill the fields. They use a simple “cat” example, but I want to use my own class I defined.

I’ve been trying to define the input and dto as such:

create-address.dto.ts:

import { Field, ObjectType } from "@nestjs/graphql";
import { myAddress } from "../addresses.model";
@ObjectType()
export class CreateAddressDto {
    @Field(type => myAddress)
    readonly address: myAddress;
}

Then, in

address.input.ts:

import { Field, InputType } from "@nestjs/graphql";
import { myAddress } from "../addresses.model";

@InputType()
export class AddressInput {
    @Field(type => myAddress)
    readonly address: myAddress;
};

This throws me an error:

throw new cannot_determine_output_type_error_1.CannotDetermineOutputTypeError(hostType);
^
Error: Cannot determine a GraphQL output type for the “address”. Make sure your class is decorated with an appropriate decorator.
at OutputTypeFactory.create

Which I believe I understand, but my question is: Can we use custom classes and types when we want to create such input and dto files? Or GraphQL can only handle primitive types? (string, Int…).

To extend my situation, I would like to create some custom class from classes from other packages. So I would not be writing myself every single field, but will be borrowing models from other packages. If that makes sense…
To illustrate:

in address.model.ts:

import { Field, Int, ObjectType } from "@nestjs/graphql";
import { Address } from '@easypost/api';
import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
import { Document } from 'mongoose';

@ObjectType()
export class myAddress {
    @Field(type => Int, { nullable: true }) //makes it optional
    id?: number;

    @Field(type => Address, { nullable: true })
    address?: Address;

    @Field(type => String, { nullable: true })
    notes?: string;
};

export type AddressDocument = AddressDB & Document;

@Schema()
export class AddressDB {
    @Prop()
    address: myAddress;
}

export const AddressSchema = SchemaFactory.createForClass(AddressDB);

Thank you