Module serde_with::rust::default_on_error
source · [−]Expand description
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.
Converting to serde_as
The same functionality can be more clearly expressed via DefaultOnError
and using the serde_as
macro.
It can be combined with other converts as shown.
#[serde_as]
#[derive(Deserialize)]
struct A {
#[serde_as(as = "DefaultOnError")]
value: u32,
#[serde_as(as = "DefaultOnError<DisplayFromStr>")]
value2: u32,
}
Examples
#[derive(Deserialize)]
struct A {
#[serde(deserialize_with = "serde_with::rust::default_on_error::deserialize")]
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 = 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:
#[derive(Deserialize)]
struct B {
#[serde(default, deserialize_with = "serde_with::rust::default_on_error::deserialize")]
value: u32,
}
let b: B = serde_json::from_str(r#"{ }"#).unwrap();
assert_eq!(0, b.value);
Functions
Deserialize T and return the Default
value on error
Serialize value with the default serializer