From 8e5cf2af0c8cebdf6c7dfc4a45a3076cef7ed7a6 Mon Sep 17 00:00:00 2001
From: Ruihang Xia <waynestxia@gmail.com>
Date: Thu, 25 May 2023 17:21:00 +0800
Subject: [PATCH] support literal on HTTP gateway

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>
---
 src/servers/src/prom.rs | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/servers/src/prom.rs b/src/servers/src/prom.rs
index 4669a36fe2b4..61dc205bc978 100644
--- a/src/servers/src/prom.rs
+++ b/src/servers/src/prom.rs
@@ -384,11 +384,13 @@ impl PromJsonResponse {
             .map(|(tags, mut values)| {
                 let metric = tags.into_iter().collect();
                 match result_type {
-                    Some(ValueType::Vector) => Ok(PromSeries {
-                        metric,
-                        value: values.pop(),
-                        ..Default::default()
-                    }),
+                    Some(ValueType::Vector) | Some(ValueType::Scalar) | Some(ValueType::String) => {
+                        Ok(PromSeries {
+                            metric,
+                            value: values.pop(),
+                            ..Default::default()
+                        })
+                    }
                     Some(ValueType::Matrix) => Ok(PromSeries {
                         metric,
                         values,
@@ -444,6 +446,7 @@ pub async fn instant_query(
     let query_ctx = QueryContext::with(catalog, schema);
 
     let result = handler.do_query(&prom_query, Arc::new(query_ctx)).await;
+    println!("result: {:?}", result);
     let (metric_name, result_type) =
         retrieve_metric_name_and_result_type(&prom_query.query).unwrap_or_default();
     PromJsonResponse::from_query_result(result, metric_name, result_type).await
@@ -686,8 +689,8 @@ fn promql_expr_to_metric_name(expr: &PromqlExpr) -> Option<String> {
         }
         PromqlExpr::Paren(ParenExpr { expr }) => promql_expr_to_metric_name(expr),
         PromqlExpr::Subquery(SubqueryExpr { expr, .. }) => promql_expr_to_metric_name(expr),
-        PromqlExpr::NumberLiteral(_) => None,
-        PromqlExpr::StringLiteral(_) => None,
+        PromqlExpr::NumberLiteral(_) => Some(String::new()),
+        PromqlExpr::StringLiteral(_) => Some(String::new()),
         PromqlExpr::Extension(_) => None,
         PromqlExpr::VectorSelector(VectorSelector { matchers, .. }) => {
             matchers.find_matchers(METRIC_NAME).pop().cloned()