Mongoose the Typescript way…?

Question

Trying to implement a Mongoose model in Typescript. Scouring the Google has revealed only a hybrid approach (combining JS and TS). How would one go about implementing the

Answer 1

Here's a strong typed way to match a plain model with a mongoose schema. The compiler will ensure the definitions passed to mongoose.Schema matches the interface. Once you have the schema, you can use

common.ts

export type IsRequired =
  undefined extends T
  ? false
  : true;

export type FieldType =
  T extends number ? typeof Number :
  T extends string ? typeof String :
  Object;

export type Field = {
  type: FieldType,
  required: IsRequired,
  enum?: Array
};

export type ModelDefinition = {
  [P in keyof M]-?:
    M[P] extends Array ? Array> :
    Field
};

user.ts

import * as mongoose from 'mongoose';
import { ModelDefinition } from "./common";

interface User {
  userName  : string,
  password  : string,
  firstName : string,
  lastName  : string,
  email     : string,
  activated : boolean,
  roles     : Array
}

// The typings above expect the more verbose type definitions,
// but this has the benefit of being able to match required
// and optional fields with the corresponding definition.
// TBD: There may be a way to support both types.
const definition: ModelDefinition = {
  userName  : { type: String, required: true },
  password  : { type: String, required: true },
  firstName : { type: String, required: true },
  lastName  : { type: String, required: true },
  email     : { type: String, required: true },
  activated : { type: Boolean, required: true },
  roles     : [ { type: String, required: true } ]
};

const schema = new mongoose.Schema(
  definition
);

Once you have your schema, you can use methods mentioned in other answers such as

const userModel = mongoose.model('User', schema);