What gets generated

One spec in, one file out. The Go and TypeScript files come from the same model, so they hold the same pieces under each language’s names.

Spec Go TypeScript
object schema struct with strict UnmarshalJSON, Validate, and MarshalJSON when it has const properties interface plus validate<Type>
enum named type plus constants literal union plus <Type>Values
oneOf / anyOf union type with From<X>, As<X>, Value, Discriminator union type plus validate<Type>
allOf one merged struct one merged interface
contentSchema string <Field>Value() and Set<Field>Value() <type><Field>Value() and set<Type><Field>Value()
message Message<Name> constant, headers type, correlation ID location Message<Name> constant
send operation Client method Client method
receive operation, reply Handler method, DecodeReceivedMessage, Dispatch, Client.Run optional Handler method, decodeReceivedMessage, dispatch, Client.receive
server Server<Name>URL, plus URLTemplate and URLWith for variables Server<Name>URL, plus server<Name>URLWith
channel <Channel>AddressTemplate, plus <Channel>Address(...) for parameters <Channel>AddressTemplate, plus <channel>Address(...)

generate: {models: true} in the config keeps the types, codecs, validation and message constants, and leaves out message decoding, the Handler, Dispatch and the Client.

Go details

  • Required fields are values, optional and nullable ones are pointers.
  • Decoding checks required properties, additionalProperties: false, string length and pattern, numeric bounds, multipleOf, item counts, uniqueItems, property counts and dependentRequired. Failures wrap commerr.ErrValidationFailed or commerr.ErrRequiredFieldNotSet from ctxerrors.
  • Constraints of an optional array, map or raw JSON field are skipped when the field is absent, and of a nullable one when it is null.
  • UnimplementedHandler ignores every message. Its HandleUnknownMessage logs a warning and keeps reading.
  • Keywords the generated code does not enforce are listed in the type’s doc comment, under “Not enforced by the generated code”.

TypeScript details

  • Optional properties are ?:, nullable ones add | null, const properties are literal types.
  • Validators throw ValidationError with a path such as "JoinRequest.room".
  • Transport is anything with send(data: string) and close(). A browser WebSocket fits.
  • Runtime helpers are copied into the file only when the generated code calls them, so a small spec gives a small file.

Every AsyncAPI object and schema keyword, one row each, is on the AsyncAPI 3 coverage page.

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