How to gracefully show error in Ecto / Elixir?

0
votes

Something like Repo.get!(User, 10)

Bring a result like:

(Ecto.NoResultsError) expected at least one result but got none in query:

from u in Db.User,
  where: u.id == ^10

    (ecto) lib/ecto/repo/queryable.ex:80: Ecto.Repo.Queryable.one!/4

How can I gracefully return something like {:error, "No Record found"}

I can use try do block however it is frowned upon in Elixir. Or I can use Recursive function method

I thought something like this (doesn't work though, just a concept):

def find_user(id) do
  case res = Repo.get!(User, id) do
     Ecto.NoResultsError -> {:error, "not found"}
     _ -> {:ok, res}
   end
end

This is not a Phoenix application.

2
elixirecto

2 Answers

2
votes

Use Repo.get/2 and check for nil. 

case Repo.get(User, id) do
  nil -> {:error, :not_found}
  user -> {:ok, user}
end
2
votes

Although the answer bu @JayJun is perfectly valid, the [arguably] more idiomatic approach would be to implement a helper, having two different clauses:

defp gracefully_handle_get(nil), do: {:error, :not_found}
defp gracefully_handle_get(user), do: {:ok, user}

and use it that way:

User
|> Repo.get(id)
|> gracefully_handle_get()