elastic: backend-mode: fix trimEdges functionality (#56985)

pkg/tsdb/elasticsearch/response_parser.go

@@ -537,10 +537,14 @@ func (rp *responseParser) trimDatapoints(queryResult backend.DataResponse, targe
 	for _, frame := range frames {
 		for _, field := range frame.Fields {
 			if field.Len() > trimEdges*2 {
-				for i := 0; i < field.Len(); i++ {
-					if i < trimEdges || i >= field.Len()-trimEdges {
-						field.Delete(i)
-					}
+				// first we delete the first "trim" items
+				for i := 0; i < trimEdges; i++ {
+					field.Delete(0)
+				}
+
+				// then we delete the last "trim" items
+				for i := 0; i < trimEdges; i++ {
+					field.Delete(field.Len() - 1)
 				}
 			}
 		}

pkg/tsdb/elasticsearch/response_parser_test.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana-plugin-sdk-go/experimental"
 	es "github.com/grafana/grafana/pkg/tsdb/elasticsearch/client"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -776,6 +777,55 @@ func TestResponseParser(t *testing.T) {
 			assert.Equal(t, frame.Fields[1].Config.DisplayNameFromDS, "Count")
 		})
 
+		t.Run("Larger trimEdges value", func(t *testing.T) {
+			targets := map[string]string{
+				"A": `{
+					"timeField": "@timestamp",
+					"metrics": [{ "type": "count" }],
+          "bucketAggs": [
+						{
+							"type": "date_histogram",
+							"field": "@timestamp",
+							"id": "2",
+							"settings": { "trimEdges": "3" }
+						}
+					]
+				}`,
+			}
+			response := `{
+        "responses": [
+          {
+            "aggregations": {
+              "2": {
+                "buckets": [
+                  { "key": 1000, "doc_count": 10},
+                  { "key": 2000, "doc_count": 20},
+                  { "key": 3000, "doc_count": 30},
+                  { "key": 4000, "doc_count": 40},
+                  { "key": 5000, "doc_count": 50},
+                  { "key": 6000, "doc_count": 60},
+                  { "key": 7000, "doc_count": 70},
+                  { "key": 8000, "doc_count": 80},
+                  { "key": 9000, "doc_count": 90}
+                ]
+              }
+            }
+          }
+        ]
+			}`
+			rp, err := newResponseParserForTest(targets, response)
+
+			require.NoError(t, err)
+			result, err := rp.getTimeSeries()
+			require.NoError(t, err)
+			require.Len(t, result.Responses, 1)
+
+			queryRes := result.Responses["A"]
+			require.NotNil(t, queryRes)
+
+			experimental.CheckGoldenJSONResponse(t, "testdata", "trimedges_string.golden", &queryRes, false)
+		})
+
 		t.Run("No group by time", func(t *testing.T) {
 			targets := map[string]string{
 				"A": `{

pkg/tsdb/elasticsearch/testdata/trimedges_string.golden.jsonc

@@ -0,0 +1,68 @@
+//  🌟 This was machine generated.  Do not edit. 🌟
+//  
+//  Frame[0] {
+//      "custom": null
+//  }
+//  Name: 
+//  Dimensions: 2 Fields by 3 Rows
+//  +-------------------------------+------------------+
+//  | Name: time                    | Name: value      |
+//  | Labels:                       | Labels:          |
+//  | Type: []time.Time             | Type: []*float64 |
+//  +-------------------------------+------------------+
+//  | 1970-01-01 00:00:04 +0000 UTC | 40               |
+//  | 1970-01-01 00:00:05 +0000 UTC | 50               |
+//  | 1970-01-01 00:00:06 +0000 UTC | 60               |
+//  +-------------------------------+------------------+
+//  
+//  
+//  🌟 This was machine generated.  Do not edit. 🌟
+{
+  "frames": [
+    {
+      "schema": {
+        "meta": {
+          "custom": null
+        },
+        "fields": [
+          {
+            "name": "time",
+            "type": "time",
+            "typeInfo": {
+              "frame": "time.Time"
+            },
+            "config": {
+              "displayNameFromDS": "Count"
+            }
+          },
+          {
+            "name": "value",
+            "type": "number",
+            "typeInfo": {
+              "frame": "float64",
+              "nullable": true
+            },
+            "labels": {},
+            "config": {
+              "displayNameFromDS": "Count"
+            }
+          }
+        ]
+      },
+      "data": {
+        "values": [
+          [
+            4000,
+            5000,
+            6000
+          ],
+          [
+            40,
+            50,
+            60
+          ]
+        ]
+      }
+    }
+  ]
+}