Derive Macro serde_with_macros::DeserializeFromStr
source · [−]#[derive(DeserializeFromStr)]
{
// Attributes available to this derive:
#[serde_with]
}
Expand description
Deserialize value by using its FromStr
implementation
This is an alternative way to implement Deserialize
for types which also implement FromStr
by deserializing the type from string.
Ensure that the struct/enum also implements FromStr
.
If the implementation is missing, you will get an error message like
error[E0277]: the trait bound `Struct: std::str::FromStr` is not satisfied
Additionally, FromStr::Err
must implement Display
as otherwise you will see a rather unhelpful error message
Serialization with Display
is available with the matching SerializeDisplay
derive.
Attributes
Attributes for the derive can be specified via the #[serde_with(...)]
attribute on the struct or enum.
Currently, these arguments to the attribute are possible:
-
#[serde_with(crate = "...")]
: This allows usingDeserializeFromStr
whenserde_with
is not available from the crate root. This happens while renaming dependencies in Cargo.toml or when re-exporting the macro from a different crate.This argument is analogue to serde’s crate argument and the crate argument to
serde_as
.
Example
use std::str::FromStr;
#[derive(DeserializeFromStr)]
struct A {
a: u32,
b: bool,
}
impl FromStr for A {
type Err = String;
/// Parse a value like `123<>true`
fn from_str(s: &str) -> Result<Self, Self::Err> {
let mut parts = s.split("<>");
let number = parts
.next()
.ok_or_else(|| "Missing first value".to_string())?
.parse()
.map_err(|err: ParseIntError| err.to_string())?;
let bool = parts
.next()
.ok_or_else(|| "Missing second value".to_string())?
.parse()
.map_err(|err: ParseBoolError| err.to_string())?;
Ok(Self { a: number, b: bool })
}
}
let a: A = serde_json::from_str("\"159<>true\"").unwrap();
assert_eq!(A { a: 159, b: true }, a);