[Question] Is it better to return 'Result' or 'Maybe' from methods? -- .FirstOrDefault() -- What is the recommended return type?

Hello!

The title basically says it all.

Let’s say I have a method like this which uses EFCore and queries the DB:

// This method takes a 'where expression' as a parameter, then returns the first result in the result set. 
// If there are no results, null is naturally returned (thank you microsoft)
// Take note that it is nullable
public Student? GetFirstStudent(IQueryable<Student> queryable) 
{

  // dbContext removed for the example...
  return queryable.FirstOrDefault();

}

In the example above, and based on the examples in the README.md I would think that the return type should be Result<Student>

So if the ‘Student’ is null, then the Result will be failed.

BUT

Isn’t that the same purpose and functionality as Maybe<T>?

---

Questions

1.) When is it appropiate / recommended to return Result<T>

2.) When is it appropiate / recommended to return Maybet<T>

Thanks all

[vkhorikov]

Well, in your particular situation Maybe<Student> would be more appropriate. Result<Maybe<Student>> is for when for e.g you are requesting a student from an external API and that API may or may not have that student, and also it may or may not fail due to let’s say connectivity issues and you know how to process that connectivity issue.

Another example is input validation. For example, you are validating a student email address when registering a student, and that address may be empty (which is allowed) or it may be not empty but invalid (which is not allowed):

private Result<Maybe<EmailAddress>> ValidateEmailAddress(string emailAddress)
{
// ...
}

[vkhorikov]

Fail as in some issue arises where the task completes with an error

May fail and also you know how to handle this failure. Otherwise, there’s no point in wrapping it in a Result. Check out this article: https://enterprisecraftsmanship.com/posts/error-handling-exception-or-result/