Merge pull request #2000 from yuvipanda/add-tojson

Add ToJson and FromJson template functions

pkg/chartutil/files.go

@@ -17,6 +17,7 @@ package chartutil
 
 import (
 	"encoding/base64"
+	"encoding/json"
 	"path"
 	"strings"
 
@@ -189,3 +190,31 @@ func FromYaml(str string) map[string]interface{} {
 	}
 	return m
 }
+
+// ToJson takes an interface, marshals it to json, and returns a string. It will
+// always return a string, even on marshal error (empty string).
+//
+// This is designed to be called from a template.
+func ToJson(v interface{}) string {
+	data, err := json.Marshal(v)
+	if err != nil {
+		// Swallow errors inside of a template.
+		return ""
+	}
+	return string(data)
+}
+
+// FromJson converts a YAML document into a map[string]interface{}.
+//
+// This is not a general-purpose JSON parser, and will not parse all valid
+// YAML documents. Additionally, because its intended use is within templates
+// it tolerates errors. It will insert the returned error message string into
+// m["error"] in the returned map.
+func FromJson(str string) map[string]interface{} {
+	m := map[string]interface{}{}
+
+	if err := json.Unmarshal([]byte(str), &m); err != nil {
+		m["Error"] = err.Error()
+	}
+	return m
+}

pkg/chartutil/files_test.go

@@ -141,3 +141,52 @@ one:
 		t.Fatal("Expected parser error")
 	}
 }
+
+func TestToJson(t *testing.T) {
+	expect := `{"foo":"bar"}`
+	v := struct {
+		Foo string `json:"foo"`
+	}{
+		Foo: "bar",
+	}
+
+	if got := ToJson(v); got != expect {
+		t.Errorf("Expected %q, got %q", expect, got)
+	}
+}
+
+func TestFromJson(t *testing.T) {
+	doc := `{
+  "hello": "world",
+  "one": {
+      "two": "three"
+  }
+}
+`
+	dict := FromJson(doc)
+	if err, ok := dict["Error"]; ok {
+		t.Fatalf("Parse error: %s", err)
+	}
+
+	if len(dict) != 2 {
+		t.Fatal("expected two elements.")
+	}
+
+	world := dict["hello"]
+	if world.(string) != "world" {
+		t.Fatal("Expected the world. Is that too much to ask?")
+	}
+
+	// This should fail because we don't currently support lists:
+	doc2 := `
+[
+ "one",
+ "two",
+ "three"
+]
+`
+	dict = FromJson(doc2)
+	if _, ok := dict["Error"]; !ok {
+		t.Fatal("Expected parser error")
+	}
+}

pkg/engine/engine.go

@@ -72,6 +72,8 @@ func FuncMap() template.FuncMap {
 	extra := template.FuncMap{
 		"toYaml":   chartutil.ToYaml,
 		"fromYaml": chartutil.FromYaml,
+		"toJson":   chartutil.ToJson,
+		"fromJson": chartutil.FromJson,
 
 		// This is a placeholder for the "include" function, which is
 		// late-bound to a template. By declaring it here, we preserve the