Demonstration of User Models. Keystone can display the adminUI using a boolean or virtual field.

User.boolean.js

var keystone = require('keystone'),
  Types = keystone.Field.Types;

/**
 * canAccessKeystone using a Types.Boolean
 * 
 * To set admin privileges change value of `user.canAccessKeystone`
 * ==========
 */
var User = new keystone.List('User');

User.add({
  name:               { type: Types.Name,     required: true, index: true },
  email:              { type: Types.Email,    required: true, initial: true, index: true },
  password:           { type: Types.Password, required: true, initial: true },
  canAccessKeystone:  { type: Types.Boolean,  required: true, initial: true}
);

/**
 * Registration
 */
User.defaultColumns = 'name, email, isAdmin';
User.register();

User.virtual.js

/*
 * show AdminUI only if the user is an admin
 * or, the user is a moderator who has paid money
 */
var keystone = require('keystone'),
  Types = keystone.Field.Types;

var User = new keystone.List('User');

User.add({
  name:         { type: Types.Name,     required: true, index: true },
  email:        { type: Types.Email,    required: true, initial: true, index: true },
  password:     { type: Types.Password, required: true, initial: true },
  paidBalance:  { type: Types.Boolean },
  moderator:    { type: Types.Boolean }
}, 'Permissions', {
  isAdmin: { type: Boolean, label: 'Can access Keystone', index: true }
});

// Provide access to Keystone
User.schema.virtual('canAccessKeystone').get(function() {
  if (this.isAdmin) {
  return true;
  } else if (this.paidBalance && this.moderator){
  return true;
  } else {
  return false;
  }
});

/**
 * Registration
 */
User.defaultColumns = 'name, email, isAdmin';
User.register();

If the user is "this.isAdmin" I would like to show the "User" List in Admin UI,
If not, the "User" list should not be shown.
==> Only the Admin should have access to User List

How should one implement that?