From 1870ede745a932a69fc576e6fe878d15dc3cfcfa Mon Sep 17 00:00:00 2001
From: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
Date: Mon, 1 Nov 2021 14:38:49 +0900
Subject: [PATCH] Allow `--format=json` as an alias of `--format={{json .}}`

Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>
---
 templates/templates.go      |  8 ++++++++
 templates/templates_test.go | 20 ++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/templates/templates.go b/templates/templates.go
index 0e8dd1536874..d75a65095b90 100644
--- a/templates/templates.go
+++ b/templates/templates.go
@@ -61,6 +61,11 @@ var HeaderFunctions = template.FuncMap{
 	},
 }
 
+// aliases for convenience
+var aliases = map[string]string{
+	"json": "{{json .}}",
+}
+
 // Parse creates a new anonymous template with the basic functions
 // and parses the given format.
 func Parse(format string) (*template.Template, error) {
@@ -76,6 +81,9 @@ func New(tag string) *template.Template {
 // NewParse creates a new tagged template with the basic functions
 // and parses the given format.
 func NewParse(tag, format string) (*template.Template, error) {
+	if alias, ok := aliases[format]; ok {
+		format = alias
+	}
 	return New(tag).Parse(format)
 }
 
diff --git a/templates/templates_test.go b/templates/templates_test.go
index de71ef610c3c..0a83610eb6d1 100644
--- a/templates/templates_test.go
+++ b/templates/templates_test.go
@@ -39,6 +39,26 @@ func TestNewParse(t *testing.T) {
 	assert.Check(t, is.Equal(want, b.String()))
 }
 
+func TestParseJSON(t *testing.T) {
+	f := func(t testing.TB, format string) {
+		tm, err := Parse(format)
+		assert.NilError(t, err)
+		var b bytes.Buffer
+		m := map[string]int{
+			"foo": 42,
+		}
+		assert.NilError(t, tm.Execute(&b, m))
+		want := `{"foo":42}`
+		assert.Check(t, is.Equal(want, b.String()))
+	}
+	t.Run("CanonicalForm", func(t *testing.T) {
+		f(t, "{{json .}}")
+	})
+	t.Run("ConvenienceForm", func(t *testing.T) {
+		f(t, "json")
+	})
+}
+
 func TestParseTruncateFunction(t *testing.T) {
 	source := "tupx5xzf6hvsrhnruz5cr8gwp"