How to protect the password field in mongoose and it wont return in a query

You can change the default behavior at the schema definition level using the select attribute of the field:

shell
password: { type: String, select: false }

Then you can pull it in as needed in find and populate calls via field selection as '+password'. For example:

shell
Users.findOne({_id: id}).select('+password').exec(...);

.populate('user' , '-password')

http://mongoosejs.com/docs/populate.html

JohnnyHKs answer using Schema options is probably the way to go here.

Also note that query.exclude() only exists in the 2.x branch.

Edit:

After trying both approaches, I found that the exclude always approach wasn't working for me for some reason using passport-local strategy, don't really know why.

So, this is what I ended up using:

shell
Blogs.findOne({_id: id})
    .populate("user", "-password -someOtherField -AnotherField")
    .populate("comments.items.user")
    .exec(function(error, result) {
        if(error) handleError(error);
        callback(error, result);
    });

There's nothing wrong with the exclude always approach, it just didn't work with passport for some reason, my tests told me that in fact the password was being excluded / included when I wanted. The only problem with the include always approach is that I basically need to go through every call I do to the database and exclude the password which is a lot of work.

---

After a couple of great answers I found out there are two ways of doing this, the "always include and exclude sometimes" and the "always exclude and include sometimes"?

An example of both:

The include always but exclude sometimes example:

shell
Users.find().select("-password")

or

shell
Users.find().exclude("password")

The exclude always but include sometimes example:

shell
Users.find().select("+password")

but you must define in the schema:

shell
password: { type: String, select: false }

You can achieve that using the schema, for example:

shell
const UserSchema = new Schema({/* */})

UserSchema.set('toJSON', {
    transform: function(doc, ret, opt) {
        delete ret['password']
        return ret
    }
})

const User = mongoose.model('User', UserSchema)
User.findOne() // This should return an object excluding the password field

User.find().select('-password') is the right answer. You can not add select: false on the Schema since it will not work, if you want to login.

Mongoose is a MongoDB object modeling library designed for asynchronous environments. Protecting password fields in Mongoose typically requires two steps: encrypting the password and ensuring it is not included in queries.

Encrypting Passwords

The first step to protect password fields is to encrypt them before saving to the database. Typically, this is achieved using bcrypt or similar libraries. bcrypt is a secure approach as it hashes passwords and includes a salt to protect against rainbow table attacks.

In Mongoose, you can use pre-save hooks to automatically encrypt passwords before saving documents. Here is an example:

javascript
const bcrypt = require('bcrypt');
const mongoose = require('mongoose');
const Schema = mongoose.Schema;

const userSchema = new Schema({
  username: String,
  password: String,
  // Other fields...
});

// Pre-save hook for encrypting password
userSchema.pre('save', async function(next) {
  // Encrypt password only when modified or new
  if (this.isModified('password') || this.isNew) {
    try {
      const salt = await bcrypt.genSalt(10);
      const hash = await bcrypt.hash(this.password, salt);
      this.password = hash;
      next();
    } catch (error) {
      next(error);
    }
  } else {
    next();
  }
});

const User = mongoose.model('User', userSchema);

module.exports = User;

Ensuring Password Fields Are Not Included in Queries

Even if the password is encrypted, you typically do not want it included in query responses. In Mongoose, you can use query projection to exclude specific fields or set select: false in the schema to default exclude certain fields.

Example of excluding password fields in the schema:

javascript
const userSchema = new Schema({
  username: String,
  password: { type: String, select: false },
  // Other fields...
});

// ... rest of schema and model definition

When using this approach, even when performing a regular query like User.find(), the password field will not be returned. If you need the password field in a specific query, you can use .select('+password') to explicitly request it:

javascript
User.findOne({ username: 'exampleUser' }).select('+password').exec((err, user) => {
  // Now `user` object includes the password field
  // ...
});

By following these two steps, Mongoose helps ensure that password fields are properly protected and not returned by default in queries.