Struct DefaultOnNull 

pub struct DefaultOnNull<A = Same>(/* private fields */);

Uses the Default if the value is null.

A null (or a value that is null in the format, like ~ in YAML) is replaced with the default value, everything else is deserialized with the adapter A (by default Same). This is for data that sends null instead of an empty list or a zero. Missing values are handled by the inner adapter, combine it with #[deser(default)] to also accept them. Serialization uses the inner adapter.

use deser::Deserialize;
use deser::adapters::DefaultOnNull;

#[derive(Deserialize)]
pub struct Item {
    #[deser(as = DefaultOnNull)]
    tags: Vec<String>,
    #[deser(as = DefaultOnNull, default)]
    count: u32,
}

let item: Item = deser_json::from_str(r#"{"tags": null}"#).unwrap();
assert!(item.tags.is_empty());
assert_eq!(item.count, 0);

In formats where keys can be given more than once (see ContainerShape::set_multimap) collections receive the values of all occurrences of their key from the inner adapter, nulls among them are not replaced.

Trait Implementations

impl<'de, T: Default + Send, A: Deserialize<'de, T>> Deserialize<'de, T> for DefaultOnNull<A>

fn deserialize_into<'out>( out: &'out mut Option<T>, state: &mut State, ) -> SinkHandle<'out, 'de>

Creates a sink that deserializes the value into the given slot.

fn expecting() -> Cow<'static, str>

Returns what the value expects, for error messages.

fn describe_type(d: &mut dyn Describe)

Describes the Rust shape of the type.

fn initial_value() -> Option<T>

Provides the value of a missing struct field.

fn deserialize_atom( slot: &mut Slot<T, Self>, atom: Atom<'_>, state: &mut State, ) -> Result<(), Error>

Deserializes an atom into the slot.

fn deserialize_borrowed_atom( slot: &mut Slot<T, Self>, atom: Atom<'de>, state: &mut State, ) -> Result<(), Error>

Deserializes an atom that borrows from the data being deserialized into the slot.

fn deserialize_update<'out>( value: &'out mut T, state: &mut State, ) -> SinkHandle<'out, 'de>

Creates a sink that updates an existing value.

impl<T: ?Sized, A: Serialize<T>> Serialize<T> for DefaultOnNull<A>

fn serialize<'a>(value: &'a T, state: &mut State) -> Result<Emit<'a>, Error>

Serializes the value.

fn finish(value: &T, state: &mut State) -> Result<(), Error>

Invoked after the serialization finished.

fn is_optional(value: &T) -> bool

Checks if the value represents an optional value.

fn container_shape(value: &T) -> ContainerShape

Returns the shape of the value if it’s a map or sequence.

fn describe(value: &T, d: &mut dyn Describe)

Describes the Rust shape of the value.