Add :any attribute type

[abelino]

Intended to be a passthrough attribute where the value is not validated or coerced but the value must be not nil at a minimum if optional: false. The any type is useful if you want to split out schemas where the top level schema is a generic envelope containing a nested data structure that could possibly be of a polymorphic nature. Example:

struct MQTT.AWS.Shadow.Update.V1

name "aws_shadow_update"

attribute :state do
  attribute :desired, :any
end

struct MQTT.Light.State.V1

name "light_state"

attribute [:schedule] do
  attribute :start, :datetime
  attribute :stop,  :datetime
end

with {:ok, shadow} <- Speck.validate(MQTT.AWS.Shadow.Update.V1, payload),
     {:ok, light_state} <- Speck.validate(MQTT.Light.State.V1, shadow.state.desired) do
  # do something with light_state
end

[amclain]

Does :any actually mean != nil, or is it more like Map.has_key? In other words, is the following :not_present, or should it be passed through?

params = %{
  "param1" => nil
}

[abelino]

I gave this some thought and this suggestion would change how other types/options behave. Lets observe how typed attributes currently behave:

When a field is optional, we currently check if the raw_value is nil and if it isn't nil, then a best attempt coercion occurs.
When a field is strict and not optional, we check the value type and by extension validate it's not nil.

So if we unwrap that into steps, we have:

• type validation
• optional validation

Now, with the :any type, that is essentially the absence of type so if we remove type validation, everything else should remain the same. However, you did uncover something, the guard clause for do_strict_validate(:any, value, _opts) is redundant because it is already handled prior to the validation sub-routines. So, I can get rid of that.

[amclain]

Result of our offline convo:

Move forward with the same behavior as the other types. :any, optional: false considers a nil value to be :not_present, in other words "any non-nil value". To let everything pass through, use :any, optional: true.