Eval.Keep now works with non referenced vars

CHANGELOG.md

@@ -42,6 +42,8 @@ See the API docs for more details.
 
 ### Bugfixes
 
+- [#984](https://github.com/influxdata/kapacitor/issues/984): Fix bug where keeping a list of fields that where not referenced in the eval expressions would cause an error.
+
 ## v1.0.2 [2016-10-06]
 
 ### Release Notes

eval.go

@@ -167,11 +167,19 @@ func (e *EvalNode) eval(now time.Time, group models.GroupID, fields models.Field
 		if l := len(e.e.KeepList); l != 0 {
 			newFields = make(models.Fields, l)
 			for _, f := range e.e.KeepList {
-				v, err := vars.Get(f)
-				if err != nil {
-					return nil, nil, err
+				// Try the vars scope first
+				if vars.Has(f) {
+					v, err := vars.Get(f)
+					if err != nil {
+						return nil, nil, err
+					}
+					newFields[f] = v
+				} else if v, ok := fields[f]; ok {
+					// Try the raw fields next, since it may not have been a referenced var.
+					newFields[f] = v
+				} else {
+					return nil, nil, fmt.Errorf("cannot keep field %q, field does not exist", f)
 				}
-				newFields[f] = v
 			}
 		} else {
 			newFields = make(models.Fields, len(fields)+len(e.e.AsList))

integrations/data/TestStream_Eval_KeepSome.srpl

@@ -0,0 +1,3 @@
+dbname
+rpname
+types value0=0,value1=1,other=5 0000000001

integrations/streamer_test.go

@@ -886,26 +886,27 @@ stream
 		.measurement('types')
 	|eval(lambda: "value0" + "value1", lambda: "value0" - "value1")
 		.as( 'pos', 'neg')
-		.keep('value0', 'pos', 'neg')
-	|httpOut('TestStream_Eval_Keep')
+		.keep('value0', 'pos', 'neg', 'other')
+	|httpOut('TestStream_Eval_KeepSome')
 `
 	er := kapacitor.Result{
 		Series: imodels.Rows{
 			{
 				Name:    "types",
 				Tags:    nil,
-				Columns: []string{"time", "neg", "pos", "value0"},
+				Columns: []string{"time", "neg", "other", "pos", "value0"},
 				Values: [][]interface{}{[]interface{}{
 					time.Date(1971, 1, 1, 0, 0, 0, 0, time.UTC),
 					-1.0,
+					5.0,
 					1.0,
 					0.0,
 				}},
 			},
 		},
 	}
 
-	testStreamerWithOutput(t, "TestStream_Eval_Keep", script, 2*time.Second, er, false, nil)
+	testStreamerWithOutput(t, "TestStream_Eval_KeepSome", script, 2*time.Second, er, false, nil)
 }
 
 func TestStream_Eval_KeepSomeWithHidden(t *testing.T) {
@@ -1019,7 +1020,7 @@ stream
 	|eval(lambda: string("value"))
 		.as('value_tag')
 		.tags('value_tag')
-		.keep('value')
+		.keep('value', 'another')
 	|groupBy('value_tag')
 	|httpOut('TestStream_Eval_Tags')
 `
@@ -1028,18 +1029,20 @@ stream
 			{
 				Name:    "types",
 				Tags:    map[string]string{"value_tag": "0"},
-				Columns: []string{"time", "value"},
+				Columns: []string{"time", "another", "value"},
 				Values: [][]interface{}{[]interface{}{
 					time.Date(1971, 1, 1, 0, 0, 0, 0, time.UTC),
+					2.0,
 					0.0,
 				}},
 			},
 			{
 				Name:    "types",
 				Tags:    map[string]string{"value_tag": "1"},
-				Columns: []string{"time", "value"},
+				Columns: []string{"time", "another", "value"},
 				Values: [][]interface{}{[]interface{}{
 					time.Date(1971, 1, 1, 0, 0, 0, 0, time.UTC),
+					2.0,
 					1.0,
 				}},
 			},