From b2eb0975853fbfced39c85b5da83f0a26c30240b Mon Sep 17 00:00:00 2001
From: alemi <me@alemi.dev>
Date: Thu, 10 Nov 2022 21:53:50 +0100
Subject: [PATCH] fix: surveyor now distinguishes nulls from errors

---
 src/data/entities/metrics.rs |  8 ++------
 src/worker/surveyor.rs       | 17 +++++++++++------
 2 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/src/data/entities/metrics.rs b/src/data/entities/metrics.rs
index 5315cbf..4e4a7e7 100644
--- a/src/data/entities/metrics.rs
+++ b/src/data/entities/metrics.rs
@@ -52,12 +52,8 @@ impl Related<super::panels::Entity> for Entity {
 impl ActiveModelBehavior for ActiveModel {}
 
 impl Model {
-	pub fn extract(&self, value: &serde_json::Value) -> Result<PlotPoint, FetchError> {
-		let x = Utc::now().timestamp() as f64;
-		let y = jql::walker(value, self.query.as_str())?
-			.as_f64()
-			.ok_or(FetchError::JQLError("query result is null".to_string()))?;
-		Ok(PlotPoint { x, y })
+	pub fn extract(&self, value: &serde_json::Value) -> Result<Option<f64>, FetchError> {
+		Ok(jql::walker(value, self.query.as_str())?.as_f64())
 	}
 }
 
diff --git a/src/worker/surveyor.rs b/src/worker/surveyor.rs
index 5f9ddac..390eb4a 100644
--- a/src/worker/surveyor.rs
+++ b/src/worker/surveyor.rs
@@ -74,14 +74,19 @@ pub async fn surveyor_loop(
 							error!(target: "surveyor", "[{}] Failed setting last_update ({:?}) for source {:?} but successfully fetched '{}', aborting", index, e, source_clone, res);
 							return;
 						}
+						let now = Utc::now().timestamp() as f64;
 						for metric in metrics_snapshot.iter().filter(|x| source_clone.id == x.source_id) {
 							match metric.extract(&res) {
-								Ok(v) => {
-									if let Err(e) = entities::points::Entity::insert(
-										entities::points::ActiveModel {
-											id: NotSet, metric_id: Set(metric.id), x: Set(v.x), y: Set(v.y),
-									}).exec(&db_clone).await {
-										error!(target: "surveyor", "[{}] Could not insert record {:?} : {:?}", index, v, e);
+								// note that Err and None mean different things: Err for broken queries, None for
+								// missing values. Only first one is reported
+								Ok(value) => {
+									if let Some(v) = value {
+										if let Err(e) = entities::points::Entity::insert(
+											entities::points::ActiveModel {
+												id: NotSet, metric_id: Set(metric.id), x: Set(now), y: Set(v),
+										}).exec(&db_clone).await {
+											error!(target: "surveyor", "[{}] Could not insert record ({},{}) : {:?}", index, now, v, e);
+										}
 									}
 								},
 								Err(e) => error!(target: "surveyor", "[{}] Failed extracting '{}' from {}: {:?}", index, metric.name, source_clone.name, e),