Struct serde_with::PickFirst [−][src]
pub struct PickFirst<T>(_);
Try multiple deserialization options until one succeeds.
This adapter allows you to specify a list of deserialization options. They are tried in order and the first one working is applied. Serialization always picks the first option.
PickFirst
has one type parameter which must be instanciated with a tuple of two, three, or four elements.
For example, PickFirst<(_, DisplayFromStr)>
on a field of type u32
allows to deserialize from a number or from a string via the FromStr
trait.
The value will be serialized as a number, since that is what the first type _
indicates.
Examples
Deserialize a number from either a number or a string.
#[serde_as] #[derive(Deserialize, serde::Serialize)] struct Data { #[serde_as(as = "PickFirst<(_, DisplayFromStr)>")] as_number: u32, #[serde_as(as = "PickFirst<(DisplayFromStr, _)>")] as_string: u32, } let data = Data { as_number: 123, as_string: 456 }; // Both fields can be deserialized from numbers: let j = json!({ "as_number": 123, "as_string": 456, }); assert_eq!(data, serde_json::from_value(j).unwrap()); // or from a string: let j = json!({ "as_number": "123", "as_string": "456", }); assert_eq!(data, serde_json::from_value(j).unwrap()); // For serialization the first type in the tuple determines the behavior. // The `as_number` field will use the normal `Serialize` behavior and produce a number, // while `as_string` used `Display` to produce a string. let expected = json!({ "as_number": 123, "as_string": "456", }); assert_eq!(expected, serde_json::to_value(&data).unwrap());
Trait Implementations
impl<T: Clone> Clone for PickFirst<T>
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impl<T: Copy> Copy for PickFirst<T>
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impl<T: Debug> Debug for PickFirst<T>
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impl<T: Default> Default for PickFirst<T>
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impl<'de, T, TAs1> DeserializeAs<'de, T> for PickFirst<(TAs1,)> where
TAs1: DeserializeAs<'de, T>,
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TAs1: DeserializeAs<'de, T>,
fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<'de, T, TAs1, TAs2> DeserializeAs<'de, T> for PickFirst<(TAs1, TAs2)> where
TAs1: DeserializeAs<'de, T>,
TAs2: DeserializeAs<'de, T>,
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TAs1: DeserializeAs<'de, T>,
TAs2: DeserializeAs<'de, T>,
fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<'de, T, TAs1, TAs2, TAs3> DeserializeAs<'de, T> for PickFirst<(TAs1, TAs2, TAs3)> where
TAs1: DeserializeAs<'de, T>,
TAs2: DeserializeAs<'de, T>,
TAs3: DeserializeAs<'de, T>,
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TAs1: DeserializeAs<'de, T>,
TAs2: DeserializeAs<'de, T>,
TAs3: DeserializeAs<'de, T>,
fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<'de, T, TAs1, TAs2, TAs3, TAs4> DeserializeAs<'de, T> for PickFirst<(TAs1, TAs2, TAs3, TAs4)> where
TAs1: DeserializeAs<'de, T>,
TAs2: DeserializeAs<'de, T>,
TAs3: DeserializeAs<'de, T>,
TAs4: DeserializeAs<'de, T>,
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TAs1: DeserializeAs<'de, T>,
TAs2: DeserializeAs<'de, T>,
TAs3: DeserializeAs<'de, T>,
TAs4: DeserializeAs<'de, T>,
fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<T, TAs1> SerializeAs<T> for PickFirst<(TAs1,)> where
TAs1: SerializeAs<T>,
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TAs1: SerializeAs<T>,
fn serialize_as<S>(source: &T, serializer: S) -> Result<S::Ok, S::Error> where
S: Serializer,
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S: Serializer,
impl<T, TAs1, TAs2> SerializeAs<T> for PickFirst<(TAs1, TAs2)> where
TAs1: SerializeAs<T>,
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TAs1: SerializeAs<T>,
fn serialize_as<S>(source: &T, serializer: S) -> Result<S::Ok, S::Error> where
S: Serializer,
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S: Serializer,
impl<T, TAs1, TAs2, TAs3> SerializeAs<T> for PickFirst<(TAs1, TAs2, TAs3)> where
TAs1: SerializeAs<T>,
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TAs1: SerializeAs<T>,
fn serialize_as<S>(source: &T, serializer: S) -> Result<S::Ok, S::Error> where
S: Serializer,
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S: Serializer,
impl<T, TAs1, TAs2, TAs3, TAs4> SerializeAs<T> for PickFirst<(TAs1, TAs2, TAs3, TAs4)> where
TAs1: SerializeAs<T>,
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TAs1: SerializeAs<T>,
fn serialize_as<S>(source: &T, serializer: S) -> Result<S::Ok, S::Error> where
S: Serializer,
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S: Serializer,
Auto Trait Implementations
impl<T> RefUnwindSafe for PickFirst<T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
impl<T> Send for PickFirst<T> where
T: Send,
T: Send,
impl<T> Sync for PickFirst<T> where
T: Sync,
T: Sync,
impl<T> Unpin for PickFirst<T> where
T: Unpin,
T: Unpin,
impl<T> UnwindSafe for PickFirst<T> where
T: UnwindSafe,
T: UnwindSafe,
Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,