Spectral update: struct defaults, field filtering, codec helpers, and a compile-time speedup
Struct defaults on decode
Missing JSON fields now fill from the struct’s own default values (__struct__/0) rather than always defaulting to nil. Non-nullable fields with a nil default still produce a missing_data error.
defmodule Job do
use Spectral
defstruct timeout: 30, retries: 3
@type t :: %Job{timeout: pos_integer(), retries: non_neg_integer()}
end
Spectral.decode(~s({}), Job, :t)
#=> {:ok, %Job{timeout: 30, retries: 3}}
Field filtering
New only key in @spectral accepts a list of field atoms, restricting which fields participate in encode, decode, and schema generation. Excluded fields are filled from defaults on decode and ignored on encode. Useful for computed or internal fields you never want in the API.
defmodule User do
use Spectral
defstruct [:name, :email, role: :viewer]
spectral(only: [:name, :role])
@type t :: %User{name: String.t(), email: String.t() | nil, role: atom()}
end
Spectral.encode(%User{name: "Alice", email: "alice@example.com", role: :admin}, User, :t)
#=> {:ok, ~s({"name":"Alice","role":"admin"})} # email excluded
Spectral.decode(~s({"name":"Alice","email":"alice@example.com"}), User, :t)
#=> {:ok, %User{name: "Alice", email: nil, role: :viewer}} # email ignored, role filled from default
Built-in String codec
String.t() encoding and decoding is now handled by a dedicated built-in codec rather than by reading the String module’s type definitions from its BEAM file (even when cached, this is now eliminated entirely). Constraint validation (min_length, max_length, pattern, format) works as before.
Compile-time type info
Previously, use Spectral injected a spectra_type_info/0 that built type information from the module’s BEAM abstract code at runtime (cached via persistent_term). Now the type information is fully built at compile time and baked into the generated function as a constant — no runtime work at all. No API changes needed.