1 files changed, 23 insertions, 0 deletions
diff --git a/app/helpers/safe_format_helper.rb b/app/helpers/safe_format_helper.rb
new file mode 100644
index 00000000000..c79e8b50a1a
--- /dev/null
+++ b/app/helpers/safe_format_helper.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module SafeFormatHelper
+  # Returns a HTML-safe string where +format+ and +args+ are escaped via
+  # `html_escape` if they are not marked as HTML-safe.
+  #
+  # Argument +format+ must not be marked as HTML-safe via `.html_safe`.
+  #
+  # Example:
+  #   safe_format('Some %{open}bold%{close} text.', open: '<strong>'.html_safe, close: '</strong>'.html_safe)
+  #   # => 'Some <strong>bold</strong>'
+  #   safe_format('See %{user_input}', user_input: '<b>bold</b>')
+  #   # => 'See &lt;b&gt;bold&lt;/b&gt;
+  #
+  def safe_format(format, **args)
+    raise ArgumentError, 'Argument `format` must not be marked as html_safe!' if format.html_safe?
+
+    format(
+      html_escape(format),
+      args.transform_values { |value| html_escape(value) }
+    ).html_safe
+  end
+end