add json output mode (-J) (#87)

lib/printer.go

@@ -19,6 +19,7 @@ package lib
 
 import (
 	"encoding/csv"
+	"encoding/json"
 	"fmt"
 	"io"
 	"log"
@@ -61,6 +62,8 @@ func printData(writer io.Writer, conf cfg.Config, data *Tabdata) {
 		printShellData(writer, data)
 	case cfg.Yaml:
 		printYamlData(writer, data)
+	case cfg.Json:
+		printJsonData(writer, data)
 	case cfg.CSV:
 		printCSVData(writer, conf, data)
 	default:
@@ -291,6 +294,35 @@ func printShellData(writer io.Writer, data *Tabdata) {
 	output(writer, out)
 }
 
+func printJsonData(writer io.Writer, data *Tabdata) {
+	objlist := make([]map[string]any, len(data.entries))
+
+	if len(data.entries) > 0 {
+		for i, entry := range data.entries {
+			obj := make(map[string]any, len(entry))
+
+			for idx, value := range entry {
+				num, err := strconv.Atoi(value)
+				if err == nil {
+					obj[data.headers[idx]] = num
+				} else {
+					obj[data.headers[idx]] = value
+				}
+			}
+
+			objlist[i] = obj
+		}
+	}
+
+	jsonstr, err := json.MarshalIndent(&objlist, "", "  ")
+
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	output(writer, string(jsonstr))
+}
+
 func printYamlData(writer io.Writer, data *Tabdata) {
 	type Data struct {
 		Entries []map[string]interface{} `yaml:"entries"`

lib/printer_test.go

@@ -125,6 +125,31 @@ ceta,33d12h,9,06/Jan/2008 15:04:05 -0700`,
 NAME="beta" DURATION="1d10h5m1s" COUNT="33" WHEN="3/1/2014"
 NAME="alpha" DURATION="4h35m" COUNT="170" WHEN="2013-Feb-03"
 NAME="ceta" DURATION="33d12h" COUNT="9" WHEN="06/Jan/2008 15:04:05 -0700"`,
+	},
+	{
+		name:      "json",
+		mode:      cfg.Json,
+		numberize: false,
+		expect: `[
+  {
+    "COUNT": 33,
+    "DURATION": "1d10h5m1s",
+    "NAME": "beta",
+    "WHEN": "3/1/2014"
+  },
+  {
+    "COUNT": 170,
+    "DURATION": "4h35m",
+    "NAME": "alpha",
+    "WHEN": "2013-Feb-03"
+  },
+  {
+    "COUNT": 9,
+    "DURATION": "33d12h",
+    "NAME": "ceta",
+    "WHEN": "06/Jan/2008 15:04:05 -0700"
+  }
+]`,
 	},
 	{
 		name:      "yaml",