From 8191e31f6f64ab5d485f64ea4c3a04ef871f292d Mon Sep 17 00:00:00 2001
From: Stefano Simonelli <16114781+s-simoncelli@users.noreply.github.com>
Date: Thu, 10 Oct 2024 15:56:50 +0100
Subject: [PATCH] Implement zero loss fix of PR #266

---
 pywr-schema/src/nodes/river.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/pywr-schema/src/nodes/river.rs b/pywr-schema/src/nodes/river.rs
index 0e28fd01..598ebf99 100644
--- a/pywr-schema/src/nodes/river.rs
+++ b/pywr-schema/src/nodes/river.rs
@@ -111,6 +111,10 @@ impl RiverNode {
     ) -> Result<(), SchemaError> {
         if let Some(loss_factor) = &self.loss_factor {
             let factors = loss_factor.load(network, args)?;
+            if factors.is_none() {
+                // Loaded a constant zero factor; ensure that the loss node has zero flow
+                network.set_node_max_flow(self.meta.name.as_str(), Self::loss_node_sub_name(), Some(0.0.into()))?;
+            }
             network.set_aggregated_node_relationship(self.meta.name.as_str(), Self::agg_sub_name(), factors)?;
         }