Create omitted function

Signed-off-by: Bruno Almeida <bruno.almeida@nokia.com>

pkg/engine/funcs.go

@@ -68,6 +68,8 @@ func funcMap() template.FuncMap {
 		"fromJson":      fromJSON,
 		"fromJsonArray": fromJSONArray,
 
+		"omitted": omitted,
+
 		// Duration helpers
 		"mustToDuration":       mustToDuration,
 		"durationSeconds":      durationSeconds,
@@ -268,6 +270,12 @@ func fromJSONArray(str string) []any {
 	return a
 }
 
+func omitted(a, b interface{}) interface{} {
+	if b == nil {
+		return a
+	}
+	return b
+
 // -----------------------------------------------------------------------------
 // Duration helpers (numeric and time.Duration returns)
 // -----------------------------------------------------------------------------

pkg/engine/funcs_test.go

@@ -125,6 +125,14 @@ keyInElement1 = "valueInElement1"`,
 		tpl:    `{{ fromYamlArray . }}`,
 		expect: `[error unmarshaling JSON: while decoding JSON: json: cannot unmarshal object into Go value of type []interface {}]`,
 		vars:   `hello: world`,
+	}, {
+		tpl:    `{{ .hello | omitted 'yes' }}`,
+		expect: `false`,
+		vars:   map[string]bool{"hello": false},
+	}, {
+		tpl:    `{{ .value | omitted 'yes' }}`,
+		expect: `yes`,
+		vars:   map[string]bool{"hello": false},
 	}, {
 		// This should never result in a network lookup. Regression for #7955
 		tpl:    `{{ lookup "v1" "Namespace" "" "unlikelynamespace99999999" }}`,