Attribute Reference

Supported built-in attributes, targets, and arguments.

Attributes precede the element they annotate. Use #[...] for definitions, fields, and cases, or #![...] for schema metadata. The attribute guide explains syntax.

JSON

Target	Arguments	Meaning
Opaque type	`type = "..."`, `schema = "..."`	JSON shape and optional JSON Schema reference
Record	`rename_all = "..."`	Default field naming
Field	`name = "..."`, `rename = "..."`, `inline`	Explicit name, naming convention, or flattening metadata
Variant	`rename_all = "..."`, `tagged = ...`, `tag = "..."`, `content = "..."`	Case naming and tagging
Variant case	`name = "..."`, `rename = "..."`, `content = "..."`	Case name and content field override

JSON shape names are number, boolean, string, null, object, array, and any. Combine them with |, as in "string|null".

Naming conventions are none, lowercase, UPPERCASE, camelCase, PascalCase, snake_case, SCREAMING_SNAKE_CASE, kebab-case, and SCREAMING-KEBAB-CASE.

Tagging values are unquoted paths: internally, adjacently, externally, and implicitly. Defaults are internal tagging, tag for the tag key, content for the payload key, camelCase record fields, and unchanged case names.

The parser accepts inline metadata, but flattening support is not uniform across current backends. Prefer an explicit record structure when sharing models between languages. See JSON mapping for supported tagging examples.

Rust

Target	Arguments
Definition	`type = "..."`, `derive(...)`, `attr(...)`
Field	`name = "..."`, `pub`, `pub(crate)`, `pub(super)`, `private`, `box`, `arc`, `rc`, `wrap = "..."`

Fields are public by default. pub and private cannot both apply to a field. Indirection attributes wrap the native field type without changing JSON shape. derive and attr arguments accumulate.

#[rust(derive(Clone, Debug), attr(non_exhaustive))]
record Profile {
    #[rust(private)]
    display_name: string,
}

A bare #[default] on a record field tells the Rust builder plugin to initialize it with Default::default() instead of adding it to the constructor arguments.

Python

#[py(typ = "module.Type")] maps an opaque definition to a native Python type:

#[json(type = "string")]
#[py(typ = "uuid.UUID")]
opaque UserId

The argument is named typ, while the Rust attribute uses type.

Validation

Targets are fields, records, wrappers, and opaque types. Each attribute contains one expression and optional message and code strings:

#[validate({ 1 <= _.size <= 64 }, message = "Use 1 to 64 characters.", code = "name:size")]

Repeat attributes for multiple rules. See validation for expression syntax, generator activation, and runtime limitations.

API Lifecycle

These attributes target definitions, fields, cases, and schemas:

Attribute	Arguments
`deprecated`	Optional `since`, `remove_in`, and `note` strings; may be bare
`unstable`	Optional `feature`, `note`, and `issue` strings; may be bare
`since`	Required `version` string

See API lifecycle for lint behavior and migration examples.

Requests

request applies to a request definition and requires:

name = "...": wire request identifier.
response = Type: resolved response type reference.

#[request(name = "tasks.CreateTask", response = CreateTaskOutput)]
record CreateTask {
    title: string,
}

Define or import CreateTaskOutput in the same bundle. Request metadata explains how tools can consume this relationship.

Attribute Plugin Schemas

attrs and attr describe custom typed attribute plugins:

#[attrs(plugin = "ui", target = record, repeated)]
record UiRule {
    #[attr(name = "label")]
    display_label: string,
}

They are compiler extension metadata. See extending Sidex for discovery and generator integration.

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