eventuary_core/
payload_codec.rs

1use serde::Serialize;
2use serde::de::DeserializeOwned;
3
4use crate::error::Result;
5use crate::event::Event;
6use crate::payload::Payload;
7
8pub trait PayloadCodec<P>: Clone + Send + Sync + 'static {
9    fn encode(&self, payload: &P) -> Result<Payload>;
10    fn decode(&self, payload: &Payload) -> Result<P>;
11}
12
13pub trait EventCodec<P>: Clone + Send + Sync + 'static {
14    fn encode(&self, event: &Event<P>) -> Result<Event<Payload>>;
15    fn decode(&self, event: Event<Payload>) -> Result<Event<P>>;
16}
17
18#[derive(Debug, Clone)]
19pub struct PayloadEventCodec<C> {
20    payload_codec: C,
21}
22
23impl<C> PayloadEventCodec<C> {
24    pub fn new(payload_codec: C) -> Self {
25        Self { payload_codec }
26    }
27
28    pub fn payload_codec(&self) -> &C {
29        &self.payload_codec
30    }
31}
32
33impl<P, C> EventCodec<P> for PayloadEventCodec<C>
34where
35    C: PayloadCodec<P>,
36{
37    fn encode(&self, event: &Event<P>) -> Result<Event<Payload>> {
38        event.encode_payload(&self.payload_codec)
39    }
40
41    fn decode(&self, event: Event<Payload>) -> Result<Event<P>> {
42        event.decode_payload(&self.payload_codec)
43    }
44}
45
46#[derive(Debug, Clone, Copy, Default)]
47pub struct JsonPayloadCodec;
48
49impl<P> PayloadCodec<P> for JsonPayloadCodec
50where
51    P: Serialize + DeserializeOwned,
52{
53    fn encode(&self, payload: &P) -> Result<Payload> {
54        Payload::from_json(payload)
55    }
56
57    fn decode(&self, payload: &Payload) -> Result<P> {
58        payload.to_json()
59    }
60}
61
62#[derive(Debug, Clone, Copy, Default)]
63pub struct PayloadPassthroughCodec;
64
65impl PayloadCodec<Payload> for PayloadPassthroughCodec {
66    fn encode(&self, payload: &Payload) -> Result<Payload> {
67        Ok(payload.clone())
68    }
69
70    fn decode(&self, payload: &Payload) -> Result<Payload> {
71        Ok(payload.clone())
72    }
73}
74
75#[cfg(test)]
76mod tests {
77    use super::*;
78
79    use crate::error::Error;
80
81    #[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
82    struct UserUpdated {
83        user_id: String,
84        email: String,
85    }
86
87    #[test]
88    fn json_codec_roundtrips_typed_payload() {
89        let codec = JsonPayloadCodec;
90        let typed = UserUpdated {
91            user_id: "u-1".to_owned(),
92            email: "a@example.com".to_owned(),
93        };
94
95        let payload = codec.encode(&typed).unwrap();
96        assert_eq!(payload.content_type(), crate::ContentType::Json);
97
98        let decoded: UserUpdated = codec.decode(&payload).unwrap();
99        assert_eq!(decoded, typed);
100    }
101
102    #[test]
103    fn json_codec_rejects_non_json_payload() {
104        let codec = JsonPayloadCodec;
105        let payload = Payload::from_string("not-json");
106        let decoded: Result<serde_json::Value> = codec.decode(&payload);
107        let err = decoded.unwrap_err();
108        assert!(matches!(err, Error::InvalidPayload(_)));
109    }
110
111    #[test]
112    fn payload_passthrough_clones_payload() {
113        let codec = PayloadPassthroughCodec;
114        let payload = Payload::from_string("hello");
115        let encoded = codec.encode(&payload).unwrap();
116        let decoded = codec.decode(&encoded).unwrap();
117        assert_eq!(decoded.data(), b"hello");
118        assert_eq!(decoded.content_type(), crate::ContentType::PlainText);
119    }
120
121    #[test]
122    fn payload_event_codec_encodes_and_decodes_event() {
123        let codec = PayloadEventCodec::new(JsonPayloadCodec);
124        let event: Event<UserUpdated> = Event::create(
125            "acme",
126            "/users",
127            "user.updated",
128            "thing-1",
129            UserUpdated {
130                user_id: "u-1".to_owned(),
131                email: "a@example.com".to_owned(),
132            },
133        )
134        .unwrap();
135
136        let id = event.id();
137        let encoded = codec.encode(&event).unwrap();
138        assert_eq!(encoded.id(), id);
139        assert_eq!(encoded.payload().content_type(), crate::ContentType::Json);
140
141        let decoded: Event<UserUpdated> = codec.decode(encoded).unwrap();
142        assert_eq!(decoded.id(), id);
143        assert_eq!(decoded.payload().email, "a@example.com");
144    }
145}
eventuary_core/payload_codec.rs

eventuary_core/
payload_codec.rs
