Picnic.Decode (Picnic v0.1.0)

Lenient decoding of API payloads.

The Picnic API is unofficial and its payloads drift. The decoder is built so that drift degrades gracefully instead of breaking callers:

By default responses stay plain maps — that always works.
Typed structs (Picnic.Schema.*) are an opt-in convenience: known fields are mapped in, unknown fields are ignored, missing fields become nil, and the complete original payload is stashed under :raw so nothing is ever lost.
A field with a surprising type is not an error: the value is kept as-is, a [:picnic, :schema, :drift] telemetry event is emitted, and a Logger.warning is logged. Callers who need a field the struct doesn't model can always reach into :raw.
Only a payload whose overall shape can't be reconciled with the struct at all (e.g. a bare string where an object was expected) becomes {:error, %Picnic.Error{category: :schema}}.

Summary

Functions

as(result, schema \\ nil)

Optionally casts a Picnic.HTTP.request/4 result into a schema struct.

cast(body, schema)

Casts one JSON object into schema's struct, leniently.

Functions

as(result, schema \\ nil)

@spec as(Picnic.HTTP.result(), module() | nil) :: Picnic.HTTP.result()

Optionally casts a Picnic.HTTP.request/4 result into a schema struct.

With schema set to nil the result passes through untouched (plain map). With a Picnic.Schema module, maps are cast into the struct and lists are cast element-wise. Errors pass through untouched.

cast(body, schema)

@spec cast(map(), module()) :: struct()

Casts one JSON object into schema's struct, leniently.

Never raises on payload contents: unknown fields are dropped, missing ones are nil, mistyped ones are kept verbatim (with a drift warning), and the whole original ends up under :raw.