Escaped colon in custom field choice is not preserved on edit

[deder-byte]

NetBox Edition

NetBox Community

NetBox Version

v4.4.9

Python Version

3.12

Steps to Reproduce

Create or edit a Custom Field Choice Set.

Add a choice containing a colon that is escaped with a backslash, for example:

foo\:bar:label

Save the custom field choice set.

Reopen the custom field choice set and edit the same choice again.

Observe that the backslash escape is no longer present (the value now appears as foo:bar:label).

Save the custom field choice set again.

Expected Behavior

The escaped colon (:) should be preserved when editing and re-saving the custom field choice.

The choice should remain a single literal value/label, not be reinterpreted.

Observed Behavior

The backslash escape is removed when the choice field is edited.

Upon saving, the colon is interpreted as a label/value separator, resulting in an unintended label/value assignment.

[jnovinger]

Confirmed. The root cause is in CustomFieldChoiceSetForm.__init__(). When converting stored choices back to the form field for editing, colons within values/labels aren't being re-escaped. This converts ['foo:bar', 'label'] to 'foo:bar:label', which the parser then splits incorrectly to ['foo', 'bar:label'] on the next save.

PR #14469 changed the separator from comma to colon. Jeremy requested escape support in review, noting that colons would need escaping unlike commas. PR #14470 added the escape/unescape logic using the (?<!\\): regex pattern two days later. However, PR #18631 rewrote the __init__ method to fix #17796 (an IndexError when using "Create & Add Another") and inadvertently removed the re-escaping logic, leaving only the parsing side intact.

The fix is to re-escape colons in both value and label before joining them, ensuring proper round-trip handling when editing existing choice sets.