extend-mongoose-schema.js

import mongoose from 'mongoose'

/**
 * Inherate from another existing mongoose schema
 * @param {mongoose.Schema} parentSchema Any existing mongoose.Schema e.g UserSchema
 * @param {{}} redefineOrAddFieldsOrEmpty see example below:
 * @param {{}} options https://mongoosejs.com/docs/guide.html#options
 * * ALLOWS:
 * * Modifying Fields
 * * Adding Fields
 * * Adding Mongoose Options
 * * Remove fields? (Untested/Unlikely)
 * * USAGE

 * @example
  // Imported Example Schema to extend.
  const UserSchema = new mongoose.Schema({
    firstname: {type: String},
    lastname: {type: String},
    phone: {type: String},
    email: {type: String, unique: true, required: true},
    passwordHash: {type: String, required: true}
  })

  // Field are refined here.
  const redefineOrAddFieldsOrEmpty = {
    // Modified
    firstname: { type: String, required: true },
     // Modified
    lastname: { type: String, required: true },
    // Field Added
    adminID: { type: Number, max: 0, min: 99999 required: true }
  }
  // Create the new Schema AdminUserSchema
  // Which inherates from the UserSchema
  // redefineOrAddFieldsOrEmpty take user define object to extend/modify
  AdminUserSchema = extendSchema(UserSchema, redefineOrAddFieldsOrEmpty)

 * @license MIT https://opensource.org/licenses/MIT
 * @author Jerome Hurley
*/
function extendSchema (parentSchema, redefineOrAddFieldsOrEmpty, options) {
  return new mongoose.Schema(Object.assign({}, parentSchema.obj, redefineOrAddFieldsOrEmpty), options)
}

export default extendSchema