Merge pull request #101 from cli/jq-empty-array

Fix printing empty arrays as result of jq expressions

Author: mislav

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
 			}
 		}

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{