Struct serde_with::OneOrMany [−][src]
Deserialize one or many elements
Sometime it is desireable to have a shortcut in writing 1-element lists in a config file.
Usually, this is done by either writing a list or the list element itself.
This distinction is not semantically important on the Rust side, thus both forms should serialize into the same Vec
.
The OneOrMany
adapter achieves exactly this use case.
The serialization behavior can be tweaked to either always serialize as a list using PreferMany
or to serialize as the inner element if possible using PreferOne
.
By default PreferOne
is assumed, which can also be omitted like OneOrMany<_>
.
Examples
#[serde_as] #[derive(Deserialize, serde::Serialize)] struct Data { #[serde_as(deserialize_as = "OneOrMany<_, PreferOne>")] countries: Vec<String>, #[serde_as(deserialize_as = "OneOrMany<_, PreferMany>")] cities: Vec<String>, } // The adapter allows deserializing a `Vec` from either // a single element let j = json!({ "countries": "Spain", "cities": "Berlin", }); assert!(serde_json::from_value::<Data>(j).is_ok()); // or from a list. let j = json!({ "countries": ["Germany", "France"], "cities": ["Amsterdam"], }); assert!(serde_json::from_value::<Data>(j).is_ok()); // For serialization you can choose how a single element should be encoded. // Either directly, with `PreferOne` (default), or as a list with `PreferMany`. let data = Data { countries: vec!["Spain".to_string()], cities: vec!["Berlin".to_string()], }; let j = json!({ "countries": "Spain", "cities": ["Berlin"], }); assert_eq!(data, serde_json::from_value(j).unwrap());
Trait Implementations
impl<T: Clone, FORMAT: Clone + Format> Clone for OneOrMany<T, FORMAT>
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impl<T: Copy, FORMAT: Copy + Format> Copy for OneOrMany<T, FORMAT>
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impl<T: Debug, FORMAT: Debug + Format> Debug for OneOrMany<T, FORMAT>
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impl<T: Default, FORMAT: Default + Format> Default for OneOrMany<T, FORMAT>
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impl<'de, T, U, FORMAT> DeserializeAs<'de, Vec<T, Global>> for OneOrMany<U, FORMAT> where
U: DeserializeAs<'de, T>,
FORMAT: Format,
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U: DeserializeAs<'de, T>,
FORMAT: Format,
fn deserialize_as<D>(deserializer: D) -> Result<Vec<T>, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<T, U> SerializeAs<Vec<T, Global>> for OneOrMany<U, PreferOne> where
U: SerializeAs<T>,
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U: SerializeAs<T>,
fn serialize_as<S>(source: &Vec<T>, serializer: S) -> Result<S::Ok, S::Error> where
S: Serializer,
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S: Serializer,
impl<T, U> SerializeAs<Vec<T, Global>> for OneOrMany<U, PreferMany> where
U: SerializeAs<T>,
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U: SerializeAs<T>,
fn serialize_as<S>(source: &Vec<T>, serializer: S) -> Result<S::Ok, S::Error> where
S: Serializer,
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S: Serializer,
Auto Trait Implementations
impl<T, FORMAT> RefUnwindSafe for OneOrMany<T, FORMAT> where
FORMAT: RefUnwindSafe,
T: RefUnwindSafe,
FORMAT: RefUnwindSafe,
T: RefUnwindSafe,
impl<T, FORMAT> Send for OneOrMany<T, FORMAT> where
FORMAT: Send,
T: Send,
FORMAT: Send,
T: Send,
impl<T, FORMAT> Sync for OneOrMany<T, FORMAT> where
FORMAT: Sync,
T: Sync,
FORMAT: Sync,
T: Sync,
impl<T, FORMAT> Unpin for OneOrMany<T, FORMAT> where
FORMAT: Unpin,
T: Unpin,
FORMAT: Unpin,
T: Unpin,
impl<T, FORMAT> UnwindSafe for OneOrMany<T, FORMAT> where
FORMAT: UnwindSafe,
T: UnwindSafe,
FORMAT: 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>,