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WsError

The only public typed error in dango-sdk. Returned inside subscription stream items.

Definition

#[derive(Debug, Clone, thiserror::Error)]
pub enum WsError {
    #[error("WebSocket connection closed: {0}")]
    Closed(String),
 
    #[error("WebSocket transport error: {0}")]
    Transport(String),
 
    #[error("subscription returned error: {0}")]
    Subscription(serde_json::Value),
 
    #[error("failed to decode message: {0}")]
    Decode(String),
}

Variants

Closed(reason) — the server (or the network) closed the WebSocket. reason is the close-frame body if present, or "stream ended" for unexpected EOF. Terminal: the stream emits this once, then None.

Transport(message) — tokio_tungstenite reported an I/O or protocol failure. Terminal at the connection level — every subscription on the same connection fails together.

Subscription(payload) — the server sent a GraphQL error frame for this subscription id. The payload is the raw serde_json::Value. Terminal for this stream only; sibling subscriptions on the same Session keep running.

Decode(message) — the SDK could not parse a server message into the expected type. Includes Response<T> decoding failures (the schema and the client disagree).

Example

use {
    anyhow::Result,
    dango_sdk::{SubscribeBlock, WsClient, WsError, subscribe_block},
    futures::StreamExt,
};
 
#[tokio::main]
async fn main() -> Result<()> {
    let ws = WsClient::new("wss://api-mainnet.dango.zone/graphql")?;
    let mut stream = ws
        .subscribe::<SubscribeBlock>(subscribe_block::Variables {})
        .await?;
 
    while let Some(item) = stream.next().await {
        match item {
            Ok(resp) => println!("ok: {resp:?}"),
            Err(WsError::Closed(reason))         => { eprintln!("closed: {reason}"); break; }
            Err(WsError::Transport(msg))         => { eprintln!("transport: {msg}"); break; }
            Err(WsError::Subscription(payload))  =>  eprintln!("server: {payload}"),
            Err(WsError::Decode(msg))            =>  eprintln!("decode: {msg}"),
        }
    }
    Ok(())
}

Notes

  • Implements thiserror::Error. Display formats each variant per the #[error] attribute above.
  • Clone + Debug. The driver task may broadcast the same error to multiple subscription channels when a connection dies.
  • Outside subscriptions, the SDK uses anyhow::Error. There is no equivalent typed enum for HTTP errors.

See also