metadata

Types

Attributes

Free-form attribute key/value pairs attached to an event.

pub type Attributes =
  dict.Dict(String, String)

Metadata

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Tracing and correlation metadata shared by every event.

correlation_id groups events that belong to the same business transaction. causation_id points to the immediate parent event’s id. trace_id is reserved for bridging with W3C TraceContext / OpenTelemetry. attributes carries free-form string-keyed labels for routing and observability.

pub type Metadata {
  Metadata(
    correlation_id: option.Option(String),
    causation_id: option.Option(String),
    trace_id: option.Option(String),
    attributes: dict.Dict(String, String),
  )
}

Constructors

Metadata(
  correlation_id: option.Option(String),
  causation_id: option.Option(String),
  trace_id: option.Option(String),
  attributes: dict.Dict(String, String),
)

Values

attribute

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pub fn attribute(
  metadata metadata: Metadata,
  key key: String,
) -> option.Option(String)

Look up an attribute by key. Returns None when no value is set.

empty

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pub fn empty() -> Metadata

Empty metadata with no ids and no attributes.

has_attribute

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pub fn has_attribute(
  metadata metadata: Metadata,
  key key: String,
) -> Bool

True when key is present in the attribute map (regardless of its value).

with_attribute

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pub fn with_attribute(
  metadata metadata: Metadata,
  key key: String,
  value value: String,
) -> Metadata

Insert (or overwrite) a free-form attribute pair.

with_causation_id

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pub fn with_causation_id(
  metadata metadata: Metadata,
  id id: String,
) -> Metadata

Set the causation id pointing at the immediate parent event.

with_correlation_id

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pub fn with_correlation_id(
  metadata metadata: Metadata,
  id id: String,
) -> Metadata

Tag this metadata with the correlation id that groups events belonging to the same business transaction.

with_trace_id

</>

pub fn with_trace_id(
  metadata metadata: Metadata,
  id id: String,
) -> Metadata

Set the W3C/OpenTelemetry-style trace id.