Add get_or_create JetStream management API

async-nats/src/jetstream/context.rs

@@ -117,6 +117,31 @@ impl Context {
         }
     }
 
+    pub async fn get_or_create_stream<S>(&self, stream_config: S) -> Result<Stream, Error>
+    where
+        S: Into<StreamConfig>,
+    {
+        let config: StreamConfig = stream_config.into();
+        let subject = format!("{}.STREAM.INFO.{}", self.prefix, config.name);
+
+        let request: Response<StreamInfo> = self.request(subject, &()).await?;
+
+        match request {
+            Response::Err { error } if error.code == 404 => self
+                .create_stream(&config)
+                .await
+                .map(|info| Stream { info }),
+            Response::Err { error } => Err(Box::new(io::Error::new(
+                ErrorKind::Other,
+                format!(
+                    "nats: error while getting or creating stream: {}, {}",
+                    error.code, error.description
+                ),
+            ))),
+            Response::Ok(info) => Ok(Stream { info }),
+        }
+    }
+
     pub async fn delete_stream<T: AsRef<str>>(&self, stream: T) -> Result<DeleteStatus, Error> {
         let stream = stream.as_ref();
         if stream.is_empty() {

async-nats/tests/jetstream_tests.rs

@@ -100,12 +100,20 @@ mod jetstream {
     }
 
     #[tokio::test]
-    async fn add_stream() {
+    async fn create_stream() {
         let server = nats_server::run_server("tests/configs/jetstream.conf");
         let client = async_nats::connect(server.client_url()).await.unwrap();
         let context = async_nats::jetstream::new(client);
 
         context.create_stream("events").await.unwrap();
+
+        context
+            .create_stream(&StreamConfig {
+                name: "events2".to_string(),
+                ..Default::default()
+            })
+            .await
+            .unwrap();
     }
 
     #[tokio::test]
@@ -121,6 +129,40 @@ mod jetstream {
         );
     }
 
+    #[tokio::test]
+    async fn get_or_create_stream() {
+        let server = nats_server::run_server("tests/configs/jetstream.conf");
+        let client = async_nats::connect(server.client_url()).await.unwrap();
+        let context = async_nats::jetstream::new(client);
+
+        context.create_stream("events").await.unwrap();
+        assert_eq!(
+            context
+                .get_or_create_stream("events")
+                .await
+                .unwrap()
+                .info
+                .config
+                .name,
+            "events".to_string()
+        );
+
+        assert_eq!(
+            context
+                .get_or_create_stream(&StreamConfig {
+                    name: "events2".to_string(),
+                    ..Default::default()
+                })
+                .await
+                .unwrap()
+                .info
+                .config
+                .name,
+            "events2".to_string()
+        );
+    }
+
+    #[tokio::test]
     async fn delete_stream() {
         let server = nats_server::run_server("tests/configs/jetstream.conf");
         let client = async_nats::connect(server.client_url()).await.unwrap();