pub struct TryFromInto<T>(_);
Expand description

Serialize value by converting to/from a proxy type with serde support.

This adapter serializes a type O by converting it into a second type T and serializing T. Deserializing works analogue, by deserializing a T and then converting into O.

struct S {
    #[serde_as(as = "TryFromInto<T>")]
    value: O,
}

For serialization O needs to be O: TryInto<T> + Clone. For deserialization the opposite T: TryInto<O> is required. The Clone bound is required since serialize operates on a reference but TryInto implementations on references are uncommon. In both cases the TryInto::Error type must implement Display.

Note: FromInto is the more specialized version of this adapter which uses the infallible Into trait instead. TryFromInto is strictly more general and can also be used where FromInto is applicable. The example shows a use case, when only the deserialization behavior is fallible, but not serializing.

Example

#[derive(Clone, Debug, PartialEq)]
enum Boollike {
    True,
    False,
}

impl From<Boollike> for u8 { ... }
impl TryFrom<u8> for Boollike {
    type Error = String;
    fn try_from(v: u8) -> Result<Self, Self::Error> {
        match v {
            0 => Ok(Boollike::False),
            1 => Ok(Boollike::True),
            _ => Err(format!("Boolikes can only be constructed from 0 or 1 but found {}", v))
        }
    }
}

#[serde_as]
#[derive(Deserialize, Serialize)]
struct Data {
    #[serde_as(as = "TryFromInto<u8>")]
    b: Boollike,
}
let data = Data {
    b: Boollike::True,
};

// Define our expected JSON form
let j = json!({
    "b": 1,
});
// Ensure serialization and deserialization produce the expected results
assert_eq!(j, serde_json::to_value(&data).unwrap());
assert_eq!(data, serde_json::from_value(j).unwrap());

// Numbers besides 0 or 1 should be an error
let j = json!({
    "b": 2,
});
assert_eq!("Boolikes can only be constructed from 0 or 1 but found 2", serde_json::from_value::<Data>(j).unwrap_err().to_string());

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

Deserialize this value from the given Serde deserializer.

Serialize this value into the given Serde serializer.

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

Uses borrowed data to replace owned data, usually by cloning. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.