Practical GraphQL - Become a GraphQL Ninja - Solution to the Student Challenge - GraphQL Type Relationships

The video tutorial explains how to add a 'car' field to a user type in a data schema, which involves creating a custom resolver function. The process includes mapping car IDs to user data and testing the implementation to ensure it returns the correct car information for each user. The tutorial concludes with a successful test of the solution.

Describe the process of mapping car IDs to the actual car objects in the resolver function.

What happens when a user does not own any cars according to the resolver function?