Merge pull request #64 from md5/add-function-parse-json

Add parseJson function

Author: jwilder

template.go

@@ -216,6 +216,14 @@ func marshalJson(input interface{}) (string, error) {
 	return strings.TrimSuffix(buf.String(), "\n"), nil
 }
 
+func unmarshalJson(input string) (interface{}, error) {
+	var v interface{}
+	if err := json.Unmarshal([]byte(input), &v); err != nil {
+		return nil, err
+	}
+	return v, nil
+}
+
 // arrayFirst returns first item in the array or nil if the
 // input is nil or empty
 func arrayFirst(input interface{}) interface{} {
@@ -302,6 +310,7 @@ func newTemplate(name string) *template.Template {
 		"keys":          keys,
 		"last":          arrayLast,
 		"replace":       strings.Replace,
+		"parseJson":     unmarshalJson,
 		"sha1":          hashSha1,
 		"split":         strings.Split,
 		"trimPrefix":    trimPrefix,

template_test.go

@@ -3,6 +3,7 @@ package main
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"reflect"
 	"testing"
 	"text/template"
@@ -518,6 +519,37 @@ func TestJson(t *testing.T) {
 	}
 }
 
+func TestParseJson(t *testing.T) {
+	tests := []struct {
+		tmpl     string
+		context  interface{}
+		expected string
+	}{
+		{`{{parseJson .}}`, `null`, `<no value>`},
+		{`{{parseJson .}}`, `true`, `true`},
+		{`{{parseJson .}}`, `1`, `1`},
+		{`{{parseJson .}}`, `0.5`, `0.5`},
+		{`{{index (parseJson .) "enabled"}}`, `{"enabled":true}`, `true`},
+		{`{{index (parseJson . | first) "enabled"}}`, `[{"enabled":true}]`, `true`},
+	}
+
+	for n, test := range tests {
+		tmplName := fmt.Sprintf("parseJson-test-%d", n)
+		tmpl := template.Must(newTemplate(tmplName).Parse(test.tmpl))
+
+		var b bytes.Buffer
+		err := tmpl.ExecuteTemplate(&b, tmplName, test.context)
+		if err != nil {
+			t.Fatalf("Error executing template: %v", err)
+		}
+
+		got := b.String()
+		if test.expected != got {
+			t.Fatalf("Incorrect output found; expected %s, got %s", test.expected, got)
+		}
+	}
+}
+
 func TestArrayClosestExact(t *testing.T) {
 	if arrayClosest([]string{"foo.bar.com", "bar.com"}, "foo.bar.com") != "foo.bar.com" {
 		t.Fatal("Expected foo.bar.com")