[−][src]Struct serde_with::DefaultOnError
Deserialize value and return Default
on error
The main use case is ignoring error while deserializing.
Instead of erroring, it simply deserializes the Default
variant of the type.
It is not possible to find the error location, i.e., which field had a deserialization error, with this method.
The same functionality is also available as serde_with::rust::default_on_error
compatible with serde's with-annotation.
Examples
#[serde_as] #[derive(Deserialize, Debug)] struct A { #[serde_as(deserialize_as = "DefaultOnError")] value: u32, } let a: A = serde_json::from_str(r#"{"value": 123}"#).unwrap(); assert_eq!(123, a.value); // null is of invalid type let a: A = serde_json::from_str(r#"{"value": null}"#).unwrap(); assert_eq!(0, a.value); // String is of invalid type let a: A = serde_json::from_str(r#"{"value": "123"}"#).unwrap(); assert_eq!(0, a.value); // Map is of invalid type let a: A = dbg!(serde_json::from_str(r#"{"value": {}}"#)).unwrap(); assert_eq!(0, a.value); // Missing entries still cause errors assert!(serde_json::from_str::<A>(r#"{ }"#).is_err());
Deserializing missing values can be supported by adding the default
field attribute:
#[serde_as] #[derive(Deserialize)] struct B { #[serde_as(deserialize_as = "DefaultOnError")] #[serde(default)] value: u32, } let b: B = serde_json::from_str(r#"{ }"#).unwrap(); assert_eq!(0, b.value);
DefaultOnError
can be combined with other conversion methods.
In this example we deserialize a Vec
, each element is deserialized from a string.
If the string does not parse as a number, then we get the default value of 0.
#[serde_as] #[derive(Serialize, Deserialize)] struct C { #[serde_as(as = "Vec<DefaultOnError<DisplayFromStr>>")] value: Vec<u32>, }; let c: C = serde_json::from_value(json!({ "value": ["1", "2", "a3", "", {}, "6"] })).unwrap(); assert_eq!(vec![1, 2, 0, 0, 0, 6], c.value);
Trait Implementations
impl<T: Clone> Clone for DefaultOnError<T>
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fn clone(&self) -> DefaultOnError<T>
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fn clone_from(&mut self, source: &Self)
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impl<T: Copy> Copy for DefaultOnError<T>
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impl<T: Debug> Debug for DefaultOnError<T>
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impl<T: Default> Default for DefaultOnError<T>
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fn default() -> DefaultOnError<T>
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impl<'de, T, TAs> DeserializeAs<'de, T> for DefaultOnError<TAs> where
TAs: DeserializeAs<'de, T>,
T: Default,
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TAs: DeserializeAs<'de, T>,
T: Default,
fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error> where
D: Deserializer<'de>,
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D: Deserializer<'de>,
impl<T, TAs> SerializeAs<T> for DefaultOnError<TAs> where
TAs: SerializeAs<T>,
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TAs: 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 DefaultOnError<T> where
T: RefUnwindSafe,
T: RefUnwindSafe,
impl<T> Send for DefaultOnError<T> where
T: Send,
T: Send,
impl<T> Sync for DefaultOnError<T> where
T: Sync,
T: Sync,
impl<T> Unpin for DefaultOnError<T> where
T: Unpin,
T: Unpin,
impl<T> UnwindSafe for DefaultOnError<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,
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.
fn to_owned(&self) -> T
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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.
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>,