Enum FieldUpdate 

pub enum FieldUpdate<T> {
    Keep,
    Set(T),
    Clear,
}

Tri-state field for UpdateEnvironmentPayload: callers can keep the existing value, set a new one, or clear an optional field back to None.

Keep maps to the prior None behavior (no change). Set(v) maps to the prior Some(v). Clear writes None into the persisted field, which a plain Option<T> patch shape could not express.

Wire format

Serde mirrors the A8 wire encoding established by the PR-3b client: Set(v) is {"value": v}, Clear is {"clear": true}, and Keep is the absent field (every payload field carries #[serde(default, skip_serializing_if = "FieldUpdate::is_keep")]). A present-but-{"clear": false} value deserializes to Keep — the caller said “don’t clear” and named no new value.

Deserialization is strict: a body carrying both value and clear keys is rejected (contradictory patch intent), and unknown keys are rejected via deny_unknown_fields. {"value": null} is treated as absent for T that deserializes from null.

Variants

Keep

Leave the existing value unchanged (the prior None behavior).

Set(T)

Write a new value.

Clear

Clear an optional field back to None. Only valid for fields that are Option<T> on the persisted struct.

Implementations

impl<T> FieldUpdate<T>

pub fn from_option(opt: Option<T>) -> Self

Convert from Option<T> (backward-compat): None → Keep, Some(v) → Set(v). Existing callers that pass bare None keep the prior semantics with no code change beyond wrapping.

pub fn from_double_option(opt: Option<Option<T>>) -> Self

Convert from Option<Option<T>> (JSON tri-state): outer None → Keep, Some(None) → Clear, Some(Some(v)) → Set(v).

pub fn is_keep(&self) -> bool

Whether this update is a no-op.

pub fn apply_to(self, target: &mut Option<T>)

Apply this update to an Option<T> target field: Keep is a no-op, Set(v) writes Some(v), Clear writes None.

Trait Implementations

impl<T: Clone> Clone for FieldUpdate<T>

fn clone(&self) -> FieldUpdate<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Debug> Debug for FieldUpdate<T>

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

Formats the value using the given formatter.

impl<T> Default for FieldUpdate<T>

fn default() -> FieldUpdate<T>

Returns the “default value” for a type.

impl<'de, T: Deserialize<'de>> Deserialize<'de> for FieldUpdate<T>

fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl<T: Eq> Eq for FieldUpdate<T>

impl<T: PartialEq> PartialEq for FieldUpdate<T>

fn eq(&self, other: &FieldUpdate<T>) -> 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<T: Serialize> Serialize for FieldUpdate<T>

fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl<T: PartialEq> StructuralPartialEq for FieldUpdate<T>