From 60896a318634a17a1d31b3be6d75dcd3dea55a50 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mislav=20Marohni=C4=87?= <git@mislav.net>
Date: Thu, 9 Feb 2023 17:35:14 +0100
Subject: [PATCH] Fix printing empty arrays as result of jq expressions

---
 pkg/jq/jq.go      | 15 ++++++---------
 pkg/jq/jq_test.go | 16 ++++++++++++++++
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/pkg/jq/jq.go b/pkg/jq/jq.go
index b08c3ad..4e31b72 100644
--- a/pkg/jq/jq.go
+++ b/pkg/jq/jq.go
@@ -39,6 +39,8 @@ func Evaluate(input io.Reader, output io.Writer, expr string) error {
 		return err
 	}
 
+	enc := json.NewEncoder(output)
+
 	iter := code.Run(responseData)
 	for {
 		v, ok := iter.Next()
@@ -53,18 +55,13 @@ func Evaluate(input io.Reader, output io.Writer, expr string) error {
 			if err != nil {
 				return err
 			}
-		} else {
-			var jsonFragment []byte
-			jsonFragment, err = json.Marshal(v)
+		} else if tt, ok := v.([]interface{}); ok && tt == nil {
+			_, err = fmt.Fprint(output, "[]\n")
 			if err != nil {
 				return err
 			}
-			_, err = output.Write(jsonFragment)
-			if err != nil {
-				return err
-			}
-			_, err = fmt.Fprint(output, "\n")
-			if err != nil {
+		} else {
+			if err = enc.Encode(v); err != nil {
 				return err
 			}
 		}
diff --git a/pkg/jq/jq_test.go b/pkg/jq/jq_test.go
index ff96a2f..b7227fe 100644
--- a/pkg/jq/jq_test.go
+++ b/pkg/jq/jq_test.go
@@ -46,6 +46,22 @@ func TestEvaluate(t *testing.T) {
 			},
 			wantW: "{\"login\":\"monalisa\"}\n",
 		},
+		{
+			name: "empty array",
+			args: args{
+				json: strings.NewReader(`[]`),
+				expr: `.`,
+			},
+			wantW: "[]\n",
+		},
+		{
+			name: "empty array 2",
+			args: args{
+				json: strings.NewReader(`[]`),
+				expr: `[]`,
+			},
+			wantW: "[]\n",
+		},
 		{
 			name: "complex",
 			args: args{