Crate serde_this_or_that

  

Custom deserialization for fields that can be specified as multiple types.

Usage

use serde::Deserialize;
use serde_json::from_str;
use serde_this_or_that::{as_bool, as_f64, as_u64};

#[derive(Deserialize, Debug)]
#[serde(rename_all = "camelCase")]
struct MyStruct {
    #[serde(deserialize_with = "as_bool")]
    is_active: bool,
    #[serde(deserialize_with = "as_u64")]
    num_attempts: u64,
    #[serde(deserialize_with = "as_f64")]
    grade: f64,
}

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let string = r#"
    {
        "isActive": "True",
        "numAttempts": "",
        "grade": "81"
    }
    "#;

    let s: MyStruct = from_str(string)?;
    println!("{s:#?}");

    assert!(s.is_active);
    assert_eq!(s.num_attempts, 0);
    assert_eq!(s.grade, 81.0);

    Ok(())
}

Examples

You can check out sample usage of this crate in the examples/ folder in the project repo on GitHub.

Performance

The benchmarks suggest that implementing a custom Visitor as serde-this-or-that does, performs on average about 15x better than an approach with an untagged enum.

A separate benchmark compares performance against the serde_with crate: it indicates both crates perform about the same, assuming only DisplayFromStr is used. But when PickFirst is involved, serde-this-or-that appears to perform about 12x better in an average case.

The benchmarks live in the benches/ folder, and can be run with cargo bench.

Readme Docs

You can find the crate’s readme documentation on the crates.io page, or alternatively in the README.md file on the GitHub project repo.

Functions

as_bool

De-serialize either a null, bool, str, u64, or f64 as a boolean value.

as_f64

De-serialize either a null, str, f64, u64, or i64 as a float value.

as_i64

De-serialize either a null, str, i64, f64, or u64 as a signed value.

as_string

De-serialize either a null, str, bool, i64, f64, or u64 as an (owned) string value.

as_u64

De-serialize either a null, str, u64, f64, or i64 as an unsigned value.