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//! De/Serialization of JSON
//!
//! This modules is only available if using the `json` feature of the crate.
/// Serialize value as string containing JSON
///
/// # Examples
///
/// ```
/// # extern crate serde;
/// # extern crate serde_derive;
/// # extern crate serde_json;
/// # extern crate serde_with;
/// #
/// # use serde_derive::{Deserialize, Serialize};
/// #
/// #[derive(Deserialize, Serialize)]
/// struct A {
/// #[serde(with = "serde_with::json::nested")]
/// other_struct: B,
/// }
/// #[derive(Deserialize, Serialize)]
/// struct B {
/// value: usize,
/// }
///
/// let v: A = serde_json::from_str(r#"{"other_struct":"{\"value\":5}"}"#).unwrap();
/// assert_eq!(5, v.other_struct.value);
///
/// let x = A {
/// other_struct: B { value: 10 },
/// };
/// assert_eq!(r#"{"other_struct":"{\"value\":10}"}"#, serde_json::to_string(&x).unwrap());
/// ```
///
pub mod nested {
use serde::{
de::{DeserializeOwned, Deserializer, Error, Visitor},
ser::{self, Serialize, Serializer},
};
use serde_json;
use std::{fmt, marker::PhantomData};
/// Deserialize value from a string which is valid JSON
pub fn deserialize<'de, D, T>(deserializer: D) -> Result<T, D::Error>
where
D: Deserializer<'de>,
T: DeserializeOwned,
{
#[derive(Default)]
struct Helper<S: DeserializeOwned>(PhantomData<S>);
impl<'de, S> Visitor<'de> for Helper<S>
where
S: DeserializeOwned,
{
type Value = S;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
write!(formatter, "valid json object")
}
fn visit_str<E>(self, value: &str) -> Result<S, E>
where
E: Error,
{
serde_json::from_str(value).map_err(Error::custom)
}
}
deserializer.deserialize_str(Helper(PhantomData))
}
/// Serialize value as string containing JSON
///
/// # Errors
///
/// Serialization can fail if `T`'s implementation of `Serialize` decides to
/// fail, or if `T` contains a map with non-string keys.
pub fn serialize<T, S>(value: &T, serializer: S) -> Result<S::Ok, S::Error>
where
T: Serialize,
S: Serializer,
{
let s = serde_json::to_string(value).map_err(ser::Error::custom)?;
serializer.serialize_str(&*s)
}
}
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