flabk/src/astreams/serde_ext.rs

134 lines
3.9 KiB
Rust

use std::{convert::Infallible, fmt, marker::PhantomData, str::FromStr};
use serde::{
de::{self, MapAccess, Visitor},
Deserialize, Deserializer,
};
// Allows a value that's a string to be expanded into an object (move string into id property via From<IRI>)
// AND the serialization of that object itself
pub fn expand_partial<'de, T, D>(deserializer: D) -> Result<T, D::Error>
where
T: Deserialize<'de> + FromStr<Err = ()>,
D: Deserializer<'de>,
{
struct BaseExpander<T>(PhantomData<fn() -> T>);
impl<'de, T> Visitor<'de> for BaseExpander<T>
where
T: Deserialize<'de> + FromStr<Err = ()>,
{
type Value = T;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("string or map")
}
fn visit_str<E>(self, value: &str) -> Result<T, E>
where
E: de::Error,
{
Ok(FromStr::from_str(value).unwrap())
}
fn visit_map<M>(self, map: M) -> Result<T, M::Error>
where
M: MapAccess<'de>,
{
Deserialize::deserialize(de::value::MapAccessDeserializer::new(map))
}
}
deserializer.deserialize_any(BaseExpander(PhantomData))
}
// Allows deserialization of a single item into a vector of that item
// As long as they implement the From<String> trait
pub(super) fn pull_single_into_vec<'de, D, Out>(deserializer: D) -> Result<Vec<Out>, D::Error>
where
D: Deserializer<'de>,
Out: From<String> + serde::Deserialize<'de>,
{
struct VecVisitor<Out>(PhantomData<Vec<Out>>);
impl<'de, Out> Visitor<'de> for VecVisitor<Out>
where
Out: From<String> + serde::Deserialize<'de>,
{
type Value = Vec<Out>;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
let name = std::any::type_name::<Out>();
formatter.write_str(format!("{} or Vec<{}>", name, name).as_str())
}
fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
where
E: serde::de::Error,
{
Ok(vec![value.to_string().into()])
}
fn visit_seq<S>(self, visitor: S) -> Result<Self::Value, S::Error>
where
S: serde::de::SeqAccess<'de>,
{
Deserialize::deserialize(serde::de::value::SeqAccessDeserializer::new(visitor))
}
}
deserializer.deserialize_any(VecVisitor(PhantomData))
}
#[cfg(test)]
mod tests {
use flabk_derive::IRI;
use serde::Deserialize;
use super::expand_partial;
#[test]
fn expand_partial_populates_iri_from_string() {
#[derive(Deserialize, IRI, Default)]
struct Context {
pub id: String,
pub context: bool,
}
#[derive(Deserialize)]
struct WithContext {
#[serde(deserialize_with = "expand_partial")]
pub context: Context,
}
const JSONLD_INPUT: &str = r#"{"context": "https://www.w3.org/ns/activitystreams"}"#;
let result =
serde_json::from_str::<WithContext>(JSONLD_INPUT).expect("deserializing with expand");
assert!(result.context.id == "https://www.w3.org/ns/activitystreams");
assert!(result.context.context == false);
}
#[test]
fn expand_partial_expands_into_object_fully() {
#[derive(Deserialize, IRI, Default)]
struct Expanded {
pub id: String,
pub truth: bool,
}
#[derive(Deserialize)]
struct Expandable {
#[serde(deserialize_with = "expand_partial")]
pub expansive: Expanded,
}
const JSONLD_INPUT: &str = r#"{"expansive": { "id": "1", "truth": true }}"#;
let result =
serde_json::from_str::<Expandable>(JSONLD_INPUT).expect("deserializing with expand");
assert!(result.expansive.id == "1");
assert!(result.expansive.truth);
}
}