Enum FieldRole 

#[non_exhaustive]
pub enum FieldRole {
    None,
    Key,
    SpanId,
    ParentSpanId,
}

The semantic role a field plays beyond its raw type.

Roles are mutually exclusive — a field is at most one of these — so a single enum makes the illegal combinations unrepresentable instead of forcing consumers to reconcile parallel booleans. Key is the original #[event(key)] promotion; the two span roles let the trace converter pair begin/end records and build parent/child links purely from the schema.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

None

An ordinary field with no special role.

Key

A high-value join/index column the reader promotes to the top level (#[event(key)]).

SpanId

The span’s own id (#[event(span_id)]): a u64 the converter pairs enter/exit records by.

ParentSpanId

The id of the enclosing span (#[event(parent_span_id)]): a u64 linking this record to its parent, for nesting in the trace view.

Trait Implementations

impl Clone for FieldRole

fn clone(&self) -> FieldRole

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for FieldRole

impl Debug for FieldRole

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

Formats the value using the given formatter.

impl Default for FieldRole

fn default() -> FieldRole

Returns the “default value” for a type.

impl Eq for FieldRole

impl PartialEq for FieldRole

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for FieldRole