Struct PickFirst 

pub struct PickFirst<A>(/* private fields */);

Tries adapters in order until one of them accepts the value.

The adapters are given as a tuple of two to four adapters, _ stands for Same. When deserializing, the value is delivered to the adapters in order and the first one that accepts it wins. Values other than atoms are recorded and replayed for every adapter (like for untagged enums, see Recording), which keeps their source locations. If no adapter accepts the value, the error of the first adapter is reported. Missing values are handled by the first adapter. Serialization uses the first adapter.

The most common use is to accept a value in more than one form, like numbers that are also sent as strings:

use deser::adapters::{DisplayFromStr, PickFirst};
use deser::{Deserialize, Serialize};

#[derive(Serialize, Deserialize, Debug, PartialEq)]
pub struct Item {
    #[deser(as = PickFirst<(_, DisplayFromStr)>)]
    id: u64,
}

let a: Item = deser_json::from_str(r#"{"id": 42}"#).unwrap();
let b: Item = deser_json::from_str(r#"{"id": "42"}"#).unwrap();
assert_eq!(a, b);
assert_eq!(deser_json::to_string(&b).unwrap(), r#"{"id":42}"#);

Trait Implementations

impl<'de, T: Send, A1: Deserialize<'de, T>, A2: Deserialize<'de, T>> Deserialize<'de, T> for PickFirst<(A1, A2)>

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 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 describe_type(d: &mut dyn Describe)

Describes the Rust shape of the type.

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

Creates a sink that updates an existing value.

impl<'de, T: Send, A1: Deserialize<'de, T>, A2: Deserialize<'de, T>, A3: Deserialize<'de, T>> Deserialize<'de, T> for PickFirst<(A1, A2, A3)>

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 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 describe_type(d: &mut dyn Describe)

Describes the Rust shape of the type.

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

Creates a sink that updates an existing value.

impl<'de, T: Send, A1: Deserialize<'de, T>, A2: Deserialize<'de, T>, A3: Deserialize<'de, T>, A4: Deserialize<'de, T>> Deserialize<'de, T> for PickFirst<(A1, A2, A3, A4)>

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 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 describe_type(d: &mut dyn Describe)

Describes the Rust shape of the type.

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, A1: Serialize<T>, A2> Serialize<T> for PickFirst<(A1, A2)>

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.

impl<T: ?Sized, A1: Serialize<T>, A2, A3> Serialize<T> for PickFirst<(A1, A2, A3)>

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.

impl<T: ?Sized, A1: Serialize<T>, A2, A3, A4> Serialize<T> for PickFirst<(A1, A2, A3, A4)>

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.