odbc: skip result counts in fetch_optional

Author: lovasoa

sqlx-core/src/odbc/connection/executor.rs

@@ -5,7 +5,7 @@ use crate::odbc::{Odbc, OdbcConnection, OdbcQueryResult, OdbcRow, OdbcStatement,
 use either::Either;
 use futures_core::future::BoxFuture;
 use futures_core::stream::BoxStream;
-use futures_util::{future, FutureExt, StreamExt};
+use futures_util::TryStreamExt;
 
 impl<'c> Executor<'c> for &'c mut OdbcConnection {
     type Database = Odbc;
@@ -30,12 +30,17 @@ impl<'c> Executor<'c> for &'c mut OdbcConnection {
         'c: 'e,
         E: Execute<'q, Self::Database> + 'q,
     {
-        Box::pin(self.fetch_many(query).into_future().then(|(v, _)| match v {
-            Some(Ok(Either::Right(r))) => future::ok(Some(r)),
-            Some(Ok(Either::Left(_))) => future::ok(None),
-            Some(Err(e)) => future::err(e),
-            None => future::ok(None),
-        }))
+        let mut stream = self.fetch_many(query);
+
+        Box::pin(async move {
+            while let Some(step) = stream.try_next().await? {
+                if let Either::Right(row) = step {
+                    return Ok(Some(row));
+                }
+            }
+
+            Ok(None)
+        })
     }
 
     fn prepare_with<'e, 'q: 'e>(

tests/odbc/odbc.rs

@@ -174,6 +174,23 @@ async fn it_streams_multiple_result_sets() -> anyhow::Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn fetch_optional_skips_empty_result_sets() -> anyhow::Result<()> {
+    let mut conn = new::<Odbc>().await?;
+
+    if conn.dbms_name().await? != "PostgreSQL" {
+        return Ok(());
+    }
+
+    let row = conn
+        .fetch_optional("SELECT 1 WHERE 1=0; SELECT 2 AS v")
+        .await?
+        .expect("second result set should contain one row");
+
+    assert_eq!(row.try_get::<i64, _>("v")?, 2);
+    Ok(())
+}
+
 #[tokio::test]
 async fn it_handles_empty_result() -> anyhow::Result<()> {
     let mut conn = new::<Odbc>().await?;