Vulcan/packages/vulcan-posts/lib/custom_fields.js

import Users from "meteor/vulcan:users";

Users.addField([
  /**
    Count of the user's posts
  */
  {
    fieldName: "postCount",
    fieldSchema: {
      type: Number,
      optional: true,
      defaultValue: 0,
      viewableBy: ['guests'],
    }
  },
  /**
    The user's associated posts (GraphQL only)
  */
  {
    fieldName: "posts",
    fieldSchema: {
      type: Array,
      optional: true,
      viewableBy: ['guests'],
      resolveAs: {
        fieldName: 'posts',
        type: '[Post]',
        resolver: (user, args, { currentUser, Users, Posts }) => {
          const posts = Posts.find({userId: user._id}).fetch();

          // restrict documents fields
          const viewablePosts = _.filter(posts, post => Posts.checkAccess(currentUser, post));
          const restrictedPosts = Users.restrictViewableFields(currentUser, Posts, viewablePosts);
        
          return restrictedPosts;
        }
      }
    }
  }
]);