Struct ChangeId 

pub struct ChangeId { /* private fields */ }

The complete identity of a submitted command — Canton’s change ID.

The Ledger API does not identify a command by its command_id alone: it de-duplicates on the triple (user_id, act_as, command_id), and two applications sharing a participant can legitimately use the same command id. Anything that goes looking for a command’s outcome afterwards — a completion after a lost response, say — has to match on all three or it can find somebody else’s answer.

A Submission hands one of these back before the command is sent, which is the point: after an ambiguous failure the id is the only way back to the outcome, and a generated id the caller never saw is no way back at all.

Implementations

impl ChangeId

pub fn new( user_id: impl Into<String>, act_as: Vec<String>, command_id: impl Into<String>, ) -> Self

Assemble a change ID from its three parts.

An empty user_id means “whichever user the bearer token resolves to”, which is what the participant fills in when a submission leaves it unset — see Self::matches.

pub fn command_id(&self) -> &str

The command id.

pub fn user_id(&self) -> &str

The submitting user id; empty when it was left to the token.

pub fn act_as(&self) -> &[String]

The acting parties.

pub fn matches(&self, completion: &Completion) -> bool

Whether completion is the completion of this command.

The command id must match, and the acting parties must be the same set — order is not meaningful, and Canton may echo them in its own.

Two deliberate asymmetries. A user_id this side left empty is not compared: the participant resolved it from the token and the client genuinely does not know it, so requiring equality would reject every completion. And a completion that carries no act_as at all is not rejected on that ground — some rejections are reported without one, and refusing to recognise a rejection is worse than the narrow risk of a same-user, same-command-id collision it guards against.

pub fn matches_json(&self, completion: &Value) -> bool

Self::matches for a completion from the JSON transport, which carries the same three fields under their camelCase names.

The rule lives here rather than in the JSON client so that the two transports cannot come to disagree about what identifies a command.

Trait Implementations

impl Clone for ChangeId

fn clone(&self) -> ChangeId

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ChangeId

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for ChangeId

impl Hash for ChangeId

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ChangeId

fn eq(&self, other: &ChangeId) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for ChangeId