Enum Change 

pub enum Change<T> {
    Unchanged,
    Set(T),
}

A field of a partial-update (PATCH) body: absent, or a new value.

Mark the field #[serde(default)]: an absent field is Unchanged, a present one is Set with the value T reads from the input. null is therefore a value: Change<Option<T>> holds Set(None) for it (clear the column), while for a T that rejects null (String, numbers, …) the body fails validation. Validation and the schema are T’s.

use serde::Deserialize;
use siderite_validation::Change;

#[derive(Deserialize)]
struct Patch {
    #[serde(default)]
    note: Change<Option<String>>,
}

let absent: Patch = serde_json::from_str("{}").unwrap();
assert_eq!(absent.note, Change::Unchanged);
let cleared: Patch = serde_json::from_str(r#"{"note":null}"#).unwrap();
assert_eq!(cleared.note, Change::Set(None));

Variants

Unchanged

The field was absent: keep the current value.

Set(T)

The field was present: the new value.

Implementations

impl<T> Change<T>

pub fn apply(self, target: &mut T)

Store the new value in target, if there is one.

Args: target: The value to replace.

pub fn into_option(self) -> Option<T>

The new value, if the field was present.

Returns: Some for Set, None for Unchanged.

pub const fn is_set(&self) -> bool

Whether the field was present.

Trait Implementations

impl<T: Clone> Clone for Change<T>

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: Copy> Copy for Change<T>

impl<T: Debug> Debug for Change<T>

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

Formats the value using the given formatter.

impl<T> Default for Change<T>

fn default() -> Change<T>

Returns the “default value” for a type.

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

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

Deserialize this value from the given Serde deserializer.

impl<T: Eq> Eq for Change<T>

impl<T: Hash> Hash for Change<T>

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<T: PartialEq> PartialEq for Change<T>

fn eq(&self, other: &Change<T>) -> bool

Equality operator ==.

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

Inequality operator !=.

impl<T: Schema + 'static> Schema for Change<T>

fn schema(registry: &mut SchemaRegistry) -> SchemaObject

The schema definition of this type. Use SchemaRegistry::subschema for nested types.

fn schema_name() -> Option<&'static str>

Stable component name. Named types are emitted once under components.schemas and referenced with $ref.

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

impl<T: Validate> Validate for Change<T>

fn prepare(input: &mut Value, ctx: &mut ValidationContext)

Check and normalise the raw input for this type in place.

fn validate(&self, ctx: &mut ValidationContext)

Check invariants of the deserialized value.