JSON API

std.json implements the format-independent serialization interfaces and provides a JsonValue tree for dynamic JSON. json.norm defines its public signatures; see Serialization for the shared annotations and mapper interfaces.

@Serializable()
value User {
  @SerialName(name: "user_name")
  String name
}

String encoded = User(name: "Norm").toJson()
User decoded = encoded.fromJson<User>()

Automatic structural serialization accepts only explicitly marked value types. @SerialName renames a field; @SerialIgnore is allowed only on nullable fields, which decode to null. Nested values, nullable types, arrays/lists, Map<String, T>, enums without payloads, and basic scalars recursively use the same exact type shape.

fromJson<T> strictly rejects unknown fields, duplicate fields, missing non-nullable fields, numeric overflow, and trailing content. Parsing, shape, and resource-limit failures all throw JsonException; its code, path, offset, line, and column help locate data errors. Target values are created through their canonical constructors, so field interceptors and validation constraints are not bypassed.

See HTTP API for HTTP integration and the serialization runtime for runtime boundaries.

jsonSchema(type:) and functionSchema(operation:) derive JSON Schema from the same serialization shape. invokeJson(operation:, arguments:) validates and decodes a JSON object against a function signature, invokes a top-level function or bound method, and encodes the result. Omitted arguments use declared defaults; nullable arguments without defaults use null. Unknown, duplicate, missing, or mistyped arguments are rejected before invocation. Exceptions thrown by the function propagate unchanged. See JsonFunctionExecutionTest for execution tests.