error 500 fixed in orders

src/models/orders.rs

@@ -54,6 +54,23 @@ pub async fn place(
     details: Checkout,
     user: Option<&users::Model>,
 ) -> Result<Model> {
+    // Resolve the price of every line *before* opening the transaction. Pricing
+    // loads its context from the connection pool; doing it while the order
+    // transaction holds a connection would acquire a second one and can exhaust
+    // the pool (it times out under contention or a small pool). Prices are stable
+    // within a request, so this snapshot is what we charge; stock is still
+    // re-validated against the transaction below.
+    let line_variants = product_variants::Entity::find()
+        .filter(product_variants::Column::Id.is_in(items.iter().map(|(id, _)| *id)))
+        .all(&ctx.db)
+        .await?;
+    let priced = pricing::price_variants(ctx, &line_variants, user).await?;
+    let price_by_variant: std::collections::HashMap<i32, i64> = line_variants
+        .iter()
+        .zip(priced)
+        .map(|(v, p)| (v.id, p.price_cents))
+        .collect();
+
     let txn = ctx.db.begin().await?;
 
     let mut subtotal: i64 = 0;
@@ -78,10 +95,12 @@ pub async fn place(
                 )));
             }
         }
-        // Snapshot the price the buyer actually pays — public sale or, for a
-        // business account, their negotiated/lowest price (same resolver the
-        // cart and storefront use).
-        let unit_price_cents = pricing::price_variant(ctx, &variant, user).await?.price_cents;
+        // The price the buyer actually pays — public sale or, for a business
+        // account, their negotiated/lowest price (resolved above, outside the
+        // transaction, with the same resolver the cart and storefront use).
+        let unit_price_cents = *price_by_variant
+            .get(&variant.id)
+            .ok_or_else(|| Error::BadRequest("an item is no longer available".to_string()))?;
         subtotal += unit_price_cents * i64::from(*qty);
 
         if let Some(on_hand) = variant.stock {