pub struct DefaultOnError<T = Same>(/* private fields */);alloc only.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.
During serialization this wrapper does nothing.
The serialization behavior of the underlying type is preserved.
The type must implement Default for this conversion to work.
§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§
Source§impl<'de, T, TAs> DeserializeAs<'de, T> for DefaultOnError<TAs>where
TAs: DeserializeAs<'de, T>,
T: Default,
impl<'de, T, TAs> DeserializeAs<'de, T> for DefaultOnError<TAs>where
TAs: DeserializeAs<'de, T>,
T: Default,
Source§fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error>where
D: Deserializer<'de>,
fn deserialize_as<D>(deserializer: D) -> Result<T, D::Error>where
D: Deserializer<'de>,
Source§impl<T, TA> JsonSchemaAs<T> for DefaultOnError<TA>where
TA: JsonSchemaAs<T>,
Available on crate feature schemars_0_8 only.
impl<T, TA> JsonSchemaAs<T> for DefaultOnError<TA>where
TA: JsonSchemaAs<T>,
schemars_0_8 only.Source§fn schema_name() -> String
fn schema_name() -> String
Source§fn schema_id() -> Cow<'static, str>
fn schema_id() -> Cow<'static, str>
Source§fn json_schema(gen: &mut SchemaGenerator) -> Schema
fn json_schema(gen: &mut SchemaGenerator) -> Schema
Source§fn is_referenceable() -> bool
fn is_referenceable() -> bool
$ref keyword. Read moreSource§impl<T, TA> JsonSchemaAs<T> for DefaultOnError<TA>where
TA: JsonSchemaAs<T>,
Available on crate feature schemars_0_9 only.
impl<T, TA> JsonSchemaAs<T> for DefaultOnError<TA>where
TA: JsonSchemaAs<T>,
schemars_0_9 only.Source§fn schema_id() -> Cow<'static, str>
fn schema_id() -> Cow<'static, str>
Source§fn json_schema(gen: &mut SchemaGenerator) -> Schema
fn json_schema(gen: &mut SchemaGenerator) -> Schema
Source§fn inline_schema() -> bool
fn inline_schema() -> bool
$ref
keyword. Read moreSource§impl<T, TA> JsonSchemaAs<T> for DefaultOnError<TA>where
TA: JsonSchemaAs<T>,
Available on crate feature schemars_1 only.
impl<T, TA> JsonSchemaAs<T> for DefaultOnError<TA>where
TA: JsonSchemaAs<T>,
schemars_1 only.Source§fn schema_id() -> Cow<'static, str>
fn schema_id() -> Cow<'static, str>
Source§fn json_schema(gen: &mut SchemaGenerator) -> Schema
fn json_schema(gen: &mut SchemaGenerator) -> Schema
Source§fn inline_schema() -> bool
fn inline_schema() -> bool
$ref
keyword. Read more