no data case

src/datasources/prometheus.rs

@@ -40,6 +40,15 @@ impl Prometheus {
 pub fn parse_result(value: Value) -> types::Result<MetricResult> {
     // TODO: check that metric exists
     // TODO: check status: "error"
+    if value.get("data").is_none() {
+        return Err(anyhow::format_err!("no data in response"));
+    }
+    if value["data"].get("result").is_none() {
+        return Err(anyhow::format_err!("no result in response"));
+    }
+    if value["data"]["result"].as_array().unwrap().len() == 0 {
+        return Ok(Default::default());
+    }
     let metric = &value["data"]["result"][0]["metric"];
     let metric_name = metric
         .as_object()

src/main.rs

@@ -20,12 +20,15 @@ async fn main() -> types::Result<()> {
         )
         .await?;
 
-    let key = r.data.keys().nth(0).unwrap();
-    println!("{}", key);
-
-    let vs = &r.data[key];
-    for (t, v) in vs.iter() {
-        println!("{}\t{}", t, v);
+    if r.data.keys().len() > 0 {
+        let key = r.data.keys().nth(0).unwrap();
+        println!("timestamp\t{}", key);
+        let vs = &r.data[key];
+        for (t, v) in vs.iter() {
+            println!("{}\t{}", t, v);
+        }
+    } else {
+        println!("no_data");
     }
 
     Ok(())