server_fn/codec/
json.rs

use super::{Encoding, FromReq, FromRes, Streaming};
use crate::{
    error::{NoCustomError, ServerFnError},
    request::{ClientReq, Req},
    response::{ClientRes, Res},
    IntoReq, IntoRes,
};
use bytes::Bytes;
use futures::{Stream, StreamExt};
use http::Method;
use serde::{de::DeserializeOwned, Serialize};
use std::pin::Pin;
/// Pass arguments and receive responses as JSON in the body of a `POST` request.
pub struct Json;

impl Encoding for Json {
    const CONTENT_TYPE: &'static str = "application/json";
    const METHOD: Method = Method::POST;
}

impl<CustErr, T, Request> IntoReq<Json, Request, CustErr> for T
where
    Request: ClientReq<CustErr>,
    T: Serialize + Send,
{
    fn into_req(
        self,
        path: &str,
        accepts: &str,
    ) -> Result<Request, ServerFnError<CustErr>> {
        let data = serde_json::to_string(&self)
            .map_err(|e| ServerFnError::Serialization(e.to_string()))?;
        Request::try_new_post(path, accepts, Json::CONTENT_TYPE, data)
    }
}

impl<CustErr, T, Request> FromReq<Json, Request, CustErr> for T
where
    Request: Req<CustErr> + Send + 'static,
    T: DeserializeOwned,
{
    async fn from_req(req: Request) -> Result<Self, ServerFnError<CustErr>> {
        let string_data = req.try_into_string().await?;
        serde_json::from_str::<Self>(&string_data)
            .map_err(|e| ServerFnError::Args(e.to_string()))
    }
}

impl<CustErr, T, Response> IntoRes<Json, Response, CustErr> for T
where
    Response: Res<CustErr>,
    T: Serialize + Send,
{
    async fn into_res(self) -> Result<Response, ServerFnError<CustErr>> {
        let data = serde_json::to_string(&self)
            .map_err(|e| ServerFnError::Serialization(e.to_string()))?;
        Response::try_from_string(Json::CONTENT_TYPE, data)
    }
}

impl<CustErr, T, Response> FromRes<Json, Response, CustErr> for T
where
    Response: ClientRes<CustErr> + Send,
    T: DeserializeOwned + Send,
{
    async fn from_res(res: Response) -> Result<Self, ServerFnError<CustErr>> {
        let data = res.try_into_string().await?;
        serde_json::from_str(&data)
            .map_err(|e| ServerFnError::Deserialization(e.to_string()))
    }
}

/// An encoding that represents a stream of JSON data.
///
/// A server function that uses this as its output encoding should return [`StreamingJson`]
///
/// ## Browser Support for Streaming Input
///
/// Browser fetch requests do not currently support full request duplexing, which
/// means that that they do begin handling responses until the full request has been sent.
/// This means that if you use a streaming input encoding, the input stream needs to
/// end before the output will begin.
///
/// Streaming requests are only allowed over HTTP2 or HTTP3.
pub struct StreamingJson;

impl Encoding for StreamingJson {
    // Each chunk is encoded as a JSON object, but the overall stream is not valid JSON so this uses the default stream content type
    const CONTENT_TYPE: &'static str = Streaming::CONTENT_TYPE;
    const METHOD: Method = Streaming::METHOD;
}

/// A stream of typed data encoded as JSON.
///
/// A server function can return this type if its output encoding is [`StreamingJson`].
///
/// ## Browser Support for Streaming Input
///
/// Browser fetch requests do not currently support full request duplexing, which
/// means that that they do begin handling responses until the full request has been sent.
/// This means that if you use a streaming input encoding, the input stream needs to
/// end before the output will begin.
///
/// Streaming requests are only allowed over HTTP2 or HTTP3.
pub struct JsonStream<T, CustErr = NoCustomError>(
    Pin<Box<dyn Stream<Item = Result<T, ServerFnError<CustErr>>> + Send>>,
);

impl<T, CustErr> std::fmt::Debug for JsonStream<T, CustErr> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_tuple("JsonStream").finish()
    }
}

impl<T> JsonStream<T> {
    /// Creates a new `ByteStream` from the given stream.
    pub fn new(
        value: impl Stream<Item = Result<T, ServerFnError>> + Send + 'static,
    ) -> Self {
        Self(Box::pin(value.map(|value| value.map(Into::into))))
    }
}

impl<T, CustErr> JsonStream<T, CustErr> {
    /// Consumes the wrapper, returning a stream of text.
    pub fn into_inner(
        self,
    ) -> impl Stream<Item = Result<T, ServerFnError<CustErr>>> + Send {
        self.0
    }
}

impl<S, T: 'static, CustErr: 'static> From<S> for JsonStream<T, CustErr>
where
    S: Stream<Item = T> + Send + 'static,
{
    fn from(value: S) -> Self {
        Self(Box::pin(value.map(Ok)))
    }
}

impl<CustErr, S, T, Request> IntoReq<StreamingJson, Request, CustErr> for S
where
    Request: ClientReq<CustErr>,
    S: Stream<Item = T> + Send + 'static,
    T: Serialize + 'static,
{
    fn into_req(
        self,
        path: &str,
        accepts: &str,
    ) -> Result<Request, ServerFnError<CustErr>> {
        let data: JsonStream<T> = self.into();
        Request::try_new_streaming(
            path,
            accepts,
            Streaming::CONTENT_TYPE,
            data.0.map(|chunk| {
                serde_json::to_vec(&chunk)
                    .unwrap_or_else(|_| Vec::new())
                    .into()
            }),
        )
    }
}

impl<CustErr, T, S, Request> FromReq<StreamingJson, Request, CustErr> for S
where
    Request: Req<CustErr> + Send + 'static,
    // The additional `Stream<Item = T>` bound is never used, but it is required to avoid an error where `T` is unconstrained
    S: Stream<Item = T> + From<JsonStream<T>> + Send + 'static,
    T: DeserializeOwned + 'static,
{
    async fn from_req(req: Request) -> Result<Self, ServerFnError<CustErr>> {
        let data = req.try_into_stream()?;
        let s = JsonStream::new(data.map(|chunk| {
            chunk.and_then(|bytes| {
                serde_json::from_slice(bytes.as_ref())
                    .map_err(|e| ServerFnError::Deserialization(e.to_string()))
            })
        }));
        Ok(s.into())
    }
}

impl<CustErr, T, Response> IntoRes<StreamingJson, Response, CustErr>
    for JsonStream<T, CustErr>
where
    Response: Res<CustErr>,
    CustErr: 'static,
    T: Serialize + 'static,
{
    async fn into_res(self) -> Result<Response, ServerFnError<CustErr>> {
        Response::try_from_stream(
            Streaming::CONTENT_TYPE,
            self.into_inner().map(|value| {
                serde_json::to_vec(&value?)
                    .map(Bytes::from)
                    .map_err(|e| ServerFnError::Serialization(e.to_string()))
            }),
        )
    }
}

impl<CustErr, T, Response> FromRes<StreamingJson, Response, CustErr>
    for JsonStream<T>
where
    Response: ClientRes<CustErr> + Send,
    T: DeserializeOwned,
{
    async fn from_res(res: Response) -> Result<Self, ServerFnError<CustErr>> {
        let stream = res.try_into_stream()?;
        Ok(JsonStream::new(stream.map(|chunk| {
            chunk.and_then(|bytes| {
                serde_json::from_slice(bytes.as_ref())
                    .map_err(|e| ServerFnError::Deserialization(e.to_string()))
            })
        })))
    }
}
server_fn/codec/json.rs

server_fn/codec/
json.rs
