Papillon6814

Papillon6814

Handling nil in case

Hello. I’m thinking the way to handle nil in case.

|> case do
    x when not is_nil(x) -> 
      ...
      {:ok, "xxxxxx"}
    nil ->
      ...
      {:error, "xxxxxxxx"}
end
|> case do
    nil -> 
      ...
      {:error, "xxxxxxxx"}
    topic ->
      ...
      {:ok, "xxxxxxxx"}
end

When I handle nil in case, I write codes in a latter way. What do you think of that?

Most Liked

dimitarvp

dimitarvp

In case, I always go from most concrete to least concrete, like so:

case something do
  nil -> "nil"
  :a -> "the atom :a"
  text when is_binary(text) -> "text"
  list when is_list(list) -> "list"
  other -> raise(ArgumentError, "unexpected value: #{inspect(other)}"
end
kokolegorille

kokolegorille

You can also do like this, if topic is some kind of struct.

|> case do
  %Topic{} = topic -> ...
  nil -> ...
end
dmitrykleymenov

dmitrykleymenov

About piping into case a good mention was in Good and Bad Elixir post. May be you should consider to match it to some variable? Especially with nil result possibility, you could rewrite it to if some_result, do: something, else: another

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