This would be quite helpful to deal with environment variables that are
expected to be boolean or integers. In my experience, I always have to
copy-paste a helper function to do the type cast:
defp to_boolean(nil), do: false
defp to_boolean(var) when is_boolean(var) do
var
end
defp to_boolean(var) do
String.downcase(to_string(var)) in ["1", "true", "on", "yes", "y"]
end
On Tuesday, February 18, 2025 at 5:07:50 PM UTC+1 dave.lu...@gmail.com
wrote:
> In Elixir applications, config/runtime.exs is often used to parse
> environment variables from System.get_env2/ and friends, and convert into
> Application configuration.
>
> Since environment variables can only be strings, it is often necessary to
> cast from string values into booleans and integer values. E.g.
>
> config :my_app, :bool_value, System.get_env("BOOL_VALUE") == "true"
>
> config :my_app, :int_value, String.to_string(System.get_env("INT_VALUE",
> "5"))
>
> While there are entire libraries that deal with advanced runtime
> configuration, like Vapor <https://github.com/elixir-toniq/vapor> and
> elixir-specify <https://github.com/Qqwy/elixir-specify>, I believe there
> is an opportunity to simplify common patterns and duplicative code in
> Elixir configuration that often leads to confusion and edge case issues.
>
> My proposal is to add parsing for both booleans and integers to
> environment variable parsing. As an example:
>
> config :my_app, :bool_value, System.get_env_as!("BOOL_VALUE", "false", as:
> :boolean)
>
> config :my_app, :int_value, System.get_env_as!("INT_VALUE", "5", as:
> :integer)
>
> The trickiness would be in the acceptable range of edge case values. For
> example, "1" and "0" are often used for boolean values, in addition to
> "TRUE" and "FALSE". I believe there could be a reasonable compromise and
> appropriate documentation for addressing these issues.
>
> More complex parsing, such as floats and custom data types would not be
> supported.
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