Backport Iif (#31353)

modules/templates/helper.go

@@ -9,6 +9,7 @@ import (
 	"html"
 	"html/template"
 	"net/url"
+	"reflect"
 	"slices"
 	"strings"
 	"time"
@@ -237,8 +238,8 @@ func DotEscape(raw string) string {
 
 // Iif is an "inline-if", similar util.Iif[T] but templates need the non-generic version,
 // and it could be simply used as "{{Iif expr trueVal}}" (omit the falseVal).
-func Iif(condition bool, vals ...any) any {
-	if condition {
+func Iif(condition any, vals ...any) any {
+	if isTemplateTruthy(condition) {
 		return vals[0]
 	} else if len(vals) > 1 {
 		return vals[1]
@@ -246,6 +247,32 @@ func Iif(condition bool, vals ...any) any {
 	return nil
 }
 
+func isTemplateTruthy(v any) bool {
+	if v == nil {
+		return false
+	}
+
+	rv := reflect.ValueOf(v)
+	switch rv.Kind() {
+	case reflect.Bool:
+		return rv.Bool()
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		return rv.Int() != 0
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		return rv.Uint() != 0
+	case reflect.Float32, reflect.Float64:
+		return rv.Float() != 0
+	case reflect.Complex64, reflect.Complex128:
+		return rv.Complex() != 0
+	case reflect.String, reflect.Slice, reflect.Array, reflect.Map:
+		return rv.Len() > 0
+	case reflect.Struct:
+		return true
+	default:
+		return !rv.IsNil()
+	}
+}
+
 // Eval the expression and return the result, see the comment of eval.Expr for details.
 // To use this helper function in templates, pass each token as a separate parameter.
 //