Allow everyone to read or write a wiki by a repo unit setting (#30495)

Replace #6312
Help #5833
Wiki solution for #639

modules/templates/helper.go

@@ -34,6 +34,7 @@ func NewFuncMap() template.FuncMap {
 		// -----------------------------------------------------------------
 		// html/template related functions
 		"dict":         dict, // it's lowercase because this name has been widely used. Our other functions should have uppercase names.
+		"Iif":          Iif,
 		"Eval":         Eval,
 		"SafeHTML":     SafeHTML,
 		"HTMLFormat":   HTMLFormat,
@@ -238,6 +239,17 @@ func DotEscape(raw string) string {
 	return strings.ReplaceAll(raw, ".", "\u200d.\u200d")
 }
 
+// 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 {
+		return vals[0]
+	} else if len(vals) > 1 {
+		return vals[1]
+	}
+	return nil
+}
+
 // 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.
 //