Handle mongoose to json conversions in a custom plugin

src/controllers/auth.controller.js

@@ -10,7 +10,7 @@ const register = catchAsync(async (req, res) => {
   }
   const user = await User.create(req.body);
   const tokens = await tokenService.generateAuthTokens(user.id);
-  const response = { user: user.transform(), tokens };
+  const response = { user, tokens };
   res.status(httpStatus.CREATED).send(response);
 });
 
@@ -21,7 +21,7 @@ const login = catchAsync(async (req, res) => {
     throw new ApiError(httpStatus.UNAUTHORIZED, 'Incorrect email or password');
   }
   const tokens = await tokenService.generateAuthTokens(user.id);
-  const response = { user: user.transform(), tokens };
+  const response = { user, tokens };
   res.send(response);
 });
 

src/controllers/user.controller.js

@@ -10,14 +10,14 @@ const createUser = catchAsync(async (req, res) => {
     throw new ApiError(httpStatus.BAD_REQUEST, 'Email already taken');
   }
   const user = await User.create(req.body);
-  res.status(httpStatus.CREATED).send(user.transform());
+  res.status(httpStatus.CREATED).send(user);
 });
 
 const getUsers = catchAsync(async (req, res) => {
   const filter = pick(req.query, ['name', 'role']);
   const options = getQueryOptions(req.query);
   const users = await User.find(filter, null, options);
-  const response = users.map((user) => user.transform());
+  const response = users;
   res.send(response);
 });
 
@@ -26,7 +26,7 @@ const getUser = catchAsync(async (req, res) => {
   if (!user) {
     throw new ApiError(httpStatus.NOT_FOUND, 'User not found');
   }
-  res.send(user.transform());
+  res.send(user);
 });
 
 const updateUser = catchAsync(async (req, res) => {
@@ -39,7 +39,7 @@ const updateUser = catchAsync(async (req, res) => {
   }
   Object.assign(user, req.body);
   await user.save();
-  res.send(user.transform());
+  res.send(user);
 });
 
 const deleteUser = catchAsync(async (req, res) => {

src/models/token.model.js

@@ -1,4 +1,5 @@
 const mongoose = require('mongoose');
+const { toJSON } = require('./utils');
 
 const tokenSchema = mongoose.Schema(
   {
@@ -28,11 +29,12 @@ const tokenSchema = mongoose.Schema(
   },
   {
     timestamps: true,
-    toObject: { getters: true },
-    toJSON: { getters: true },
   }
 );
 
+// add plugin that converts mongoose to json
+tokenSchema.plugin(toJSON);
+
 const Token = mongoose.model('Token', tokenSchema);
 
 module.exports = Token;

src/models/user.model.js

@@ -1,7 +1,7 @@
 const mongoose = require('mongoose');
 const validator = require('validator');
 const bcrypt = require('bcryptjs');
-const { omit, pick } = require('lodash');
+const { toJSON } = require('./utils');
 const { roles } = require('../config/roles');
 
 const userSchema = mongoose.Schema(
@@ -33,6 +33,7 @@ const userSchema = mongoose.Schema(
           throw new Error('Password must contain at least one letter and one number');
         }
       },
+      private: true, // used by the toJSON plugin
     },
     role: {
       type: String,
@@ -42,11 +43,12 @@ const userSchema = mongoose.Schema(
   },
   {
     timestamps: true,
-    toObject: { getters: true },
-    toJSON: { getters: true },
   }
 );
 
+// add plugin that converts mongoose to json
+userSchema.plugin(toJSON);
+
 userSchema.statics.isEmailTaken = async function (email, excludeUserId) {
   const user = await this.findOne({ email, _id: { $ne: excludeUserId } });
   return !!user;
@@ -57,16 +59,6 @@ userSchema.methods.isPasswordMatch = async function (password) {
   return bcrypt.compare(password, user.password);
 };
 
-userSchema.methods.toJSON = function () {
-  const user = this;
-  return omit(user.toObject(), ['password']);
-};
-
-userSchema.methods.transform = function () {
-  const user = this;
-  return pick(user.toJSON(), ['id', 'email', 'name', 'role']);
-};
-
 userSchema.pre('save', async function (next) {
   const user = this;
   if (user.isModified('password')) {

src/models/utils.js

@@ -0,0 +1,36 @@
+/* eslint-disable no-param-reassign */
+
+/**
+ * A mongoose schema plugin which applies the following in the toJSON transform call:
+ *  - removes __v, createdAt, updatedAt, and any path that has private: true
+ *  - replaces _id with id
+ */
+const toJSON = (schema) => {
+  let transform;
+  if (schema.options.toJSON && schema.options.toJSON.transform) {
+    transform = schema.options.toJSON.transform;
+  }
+
+  schema.options.toJSON = Object.assign(schema.options.toJSON || {}, {
+    transform(doc, ret, options) {
+      Object.keys(schema.paths).forEach((path) => {
+        if (schema.paths[path].options && schema.paths[path].options.private) {
+          delete ret[path];
+        }
+      });
+
+      ret.id = ret._id.toString();
+      delete ret._id;
+      delete ret.__v;
+      delete ret.createdAt;
+      delete ret.updatedAt;
+      if (transform) {
+        return transform(doc, ret, options);
+      }
+    },
+  });
+};
+
+module.exports = {
+  toJSON,
+};