From 992a075cfb89512da9bcc4ee7dd706a237d0cf50 Mon Sep 17 00:00:00 2001
From: Cody Soyland <cody@soyland.org>
Date: Wed, 10 Apr 2019 15:27:12 -0500
Subject: [PATCH] Return empty result set when query empty. Fixes #1840

---
 handler.go             | 21 +++++++++++----------
 server/handler_test.go |  8 ++++++++
 2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/handler.go b/handler.go
index 988435a07..5a452ce96 100644
--- a/handler.go
+++ b/handler.go
@@ -45,18 +45,19 @@ type QueryResponse struct {
 
 // MarshalJSON marshals QueryResponse into a JSON-encoded byte slice
 func (resp *QueryResponse) MarshalJSON() ([]byte, error) {
-	var output struct {
-		Results        []interface{}    `json:"results,omitempty"`
-		ColumnAttrSets []*ColumnAttrSet `json:"columnAttrs,omitempty"`
-		Err            string           `json:"error,omitempty"`
-	}
-	output.Results = resp.Results
-	output.ColumnAttrSets = resp.ColumnAttrSets
-
 	if resp.Err != nil {
-		output.Err = resp.Err.Error()
+		return json.Marshal(struct {
+			Err string `json:"error"`
+		}{Err: resp.Err.Error()})
 	}
-	return json.Marshal(output)
+
+	return json.Marshal(struct {
+		Results        []interface{}    `json:"results"`
+		ColumnAttrSets []*ColumnAttrSet `json:"columnAttrs,omitempty"`
+	}{
+		Results:        resp.Results,
+		ColumnAttrSets: resp.ColumnAttrSets,
+	})
 }
 
 type Handler interface {
diff --git a/server/handler_test.go b/server/handler_test.go
index 701d019ae..ed7a2bed6 100644
--- a/server/handler_test.go
+++ b/server/handler_test.go
@@ -445,6 +445,14 @@ func TestHandler_Endpoints(t *testing.T) {
 		}
 	})
 
+	t.Run("Query empty", func(t *testing.T) {
+		w := httptest.NewRecorder()
+		h.ServeHTTP(w, test.MustNewHTTPRequest("POST", "/index/i0/query", strings.NewReader("")))
+		if body := w.Body.String(); body != `{"results":[]}`+"\n" {
+			t.Fatalf("unexpected body: %q", body)
+		}
+	})
+
 	t.Run("Method not allowed", func(t *testing.T) {
 		w := httptest.NewRecorder()
 		h.ServeHTTP(w, test.MustNewHTTPRequest("GET", "/index/i0/query", nil))