title: role object default value is selected even after specifying a different value from the object enum in mongoose schema
body: <p>I have created a schema named userschema.The role object default value is selcted even after specifying a different value from role enum. If I change role manually in the database everything
  works fine.</p>
  <p>Check the image below.</p>
  <pre><code> const mongoose = require('mongoose');
   const validator = require('validator');
   const bcrypt = require('bcryptjs');
      
  const userSchema = new mongoose.Schema({
          name: {
              type: String,
              required: [true , 'Name is Required'],
              unique: true
          },
          email: {
              type: String,
              required: [true , &quot;E-mail is Required&quot;],
              trim: true,
              lowercase: true,
              unique: true,
              validator:[validator.isEmail , 'Enter a Valid Email']   
          },
          photo: {
              type: String,
          },
          role:{
              type:String,
              enum: [&quot;user&quot;,&quot;guide&quot;,&quot;lead-guide&quot;,&quot;admin&quot;],
              default:&quot;user&quot;
          },
          password: {
              type: String,
              trim: true,
              minlength:8,
              required: [true , 'Enter a Password'],
              select:false
          },
          passwordConfirm: {
              type:String,
              trim:true,
              required: [true , 'Confirm Password'],
              validate: {
                  validator:function(el){
                      return el === this.password;
                  },
              message: 'Did not match the above password!'    
              }
                
          },
          passwordChangedAt: Date
      });
     
  </code></pre>
  <ol>
  <li>List item</li>
  </ol>
  <p>In the post request the role has value of &quot;admin&quot;. But after sending the request the role value is &quot;user&quot; which is also the default value in the role object.</p>