fix: preserve VALUE=DATE in DTSTART for RRULE parsing by KristjanESPERANTO · Pull Request #432 · jens-maus/node-ical

KristjanESPERANTO · 2026-01-24T00:25:48Z

Problem

When parsing recurring all-day events (VALUE=DATE), the date-only information was never passed to the RRULE library. This became visible when rrule-temporal yesterday added strict RFC 5545 validation (with v1.4.2), causing it to reject DATE-only UNTIL values:

Error: UNTIL rule part MUST have the same value type as DTSTART

Example: Google Calendar birthday events

DTSTART;VALUE=DATE:20160313
RRULE:FREQ=YEARLY;UNTIL=20190312;BYMONTHDAY=13;BYMONTH=3

Both DTSTART and UNTIL are DATE values (correct per RFC 5545), but node-ical didn't preserve VALUE=DATE when passing to rrule-temporal, causing the validation to fail.

Solution

Added check for curr.start.dateOnly to preserve the VALUE=DATE parameter.

Use local date components (not UTC) to stay consistent with how date-only events are parsed.

Testing

Yearly/monthly recurring DATE events with UNTIL
DATE events with COUNT

Impact

Fixes: Issue reported in MagicMirrorOrg/MagicMirror#4016

Affected: Users parsing recurring all-day events (birthdays, holidays) from Google Calendar and other CalDAV servers

Breaking Changes: None

Summary by CodeRabbit

Bug Fixes
- Date-only recurring events now preserve date-only semantics in recurrence rules and correctly handle UNTIL constraints without type errors, preventing incorrect validation or missing DTSTART behavior.
Tests
- Added end-to-end tests covering date-only recurring events with UNTIL, VALUE=DATE preservation, and COUNT-based recurrences to prevent regressions.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

coderabbitai · 2026-01-24T00:26:07Z

📝 Walkthrough

Walkthrough

Adds explicit handling for date-only (VALUE=DATE) VEVENTs in RRULE/DTSTART construction, emitting a local YYYYMMDD DTSTART for date-only events and adjusting RRULE assembly; includes new tests validating DATE-only RRULE parsing, UNTIL handling, and RRULE string generation.

Changes

Cohort / File(s)	Change Summary
RRULE/DTSTART DATE preservation `ical.js`	Added a dedicated branch detecting `curr.start.dateOnly` to emit `DTSTART;VALUE=DATE:YYYYMMDD` using local year/month/day before the TZID path; adjusted RRULE extraction to filter out `DTSTART` segments and `VALUE=` tokens when building the `rruleTemporal` input.
DATE-only RRULE test coverage `test/date-only-rrule-until.test.js`	New test suite (3 tests) covering: parsing DATE-only VEVENT with FREQ=YEARLY and UNTIL in the past (validates occurrences and no UNTIL type errors), preserving `VALUE=DATE` in generated RRULE strings, and COUNT-based DATE-only RRULE recurrence behavior.

Sequence Diagram(s)

(No sequence diagrams generated — changes are internal to RRULE/DTSTART formatting and tests and do not introduce multi-component interaction flows that require visualization.)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

update to detect duplicate DTSTART/DTEND in same ics event, #348 — touches DTSTART handling and duplicate-detection/signature around DTSTART/DTEND; closely related to DTSTART branch changes.
refactor: switch from rrule to rrule-temporal #422 — modifies RRULE construction and DTSTART stripping/creation; overlaps with RRULE assembly adjustments.
Convert non-UTC UNTIL to UTC for CalDAV compatibility #428 — adjusts UNTIL normalization and non-UTC TZID handling in RRULE/DTSTART logic; relevant to timezone/UNTIL interactions.

Poem

🐰 I hop through dates, no zone in sight,
I stitch YYYYMMDD to keep the bite,
RRULEs now sing with VALUE held tight,
Count and Until dance in gentle light,
Hooray—recurrences sleep sound at night! 🎉

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: preserve VALUE=DATE in DTSTART for RRULE parsing' directly and clearly summarizes the main change: addressing how VALUE=DATE is preserved when constructing RRULE strings for date-only events. The title is specific, concise, and accurately reflects the core problem being fixed.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

📝 Generate docstrings

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

coderabbitai

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@ical.js`:
- Around line 748-758: The code appends ";DTSTART;VALUE=DATE:YYYYMMDD" to the
rule string when curr.start.dateOnly is true, but the later filter that builds
rruleOnly only strips segments starting with "DTSTART", leaving an orphaned
"VALUE=DATE:YYYYMMDD" token and producing an invalid RRULE; fix by either not
injecting DTSTART into the rule string (set a separate dtstart variable and
attach it outside the RRULE) or update the filtering that produces rruleOnly to
also remove any standalone "VALUE=DATE:..." segments (e.g., strip segments
matching /^VALUE=DATE:/ or the combined ";VALUE=DATE:..."/"VALUE=DATE:..."),
referencing rule, rruleOnly, and curr.start.dateOnly to locate the change.

ical.js

When parsing recurring events with VALUE=DATE (all-day events), preserve the VALUE=DATE parameter in the DTSTART string passed to rrule-temporal. This ensures that rrule-temporal can correctly validate that UNTIL values have the same type as DTSTART. Previously, date-only information was lost when building the RRULE string, causing rrule-temporal to incorrectly assume DTSTART was DATE-TIME and reject valid DATE-only UNTIL values with the error: "UNTIL rule part MUST have the same value type as DTSTART" The fix uses local date components (getFullYear, getMonth, getDate) which is consistent with how dateOnly dates are created in the dateParameter function using new Date(year, month, day). Fixes issue reported in MagicMirrorOrg/MagicMirror#4016 where Google Calendar birthday events with yearly RRULE and DATE-only UNTIL in the past failed to parse. Test coverage: - Yearly recurring DATE events with UNTIL - Monthly recurring DATE events with UNTIL - DATE events with COUNT instead of UNTIL - Edge case: VALUE=DATE with TZID (correctly ignores TZID)

KristjanESPERANTO · 2026-01-26T18:33:56Z

coderabbit seems to be satisfied here too 😃 @jens-maus, if you have the time, it would be nice if you have a look.

jens-maus · 2026-01-26T19:50:59Z

Thanks @KristjanESPERANTO for the reminder and big thanks for this PR and all your efforts. Will of course merge it immediately.

…al 1.4.2+ PR jens-maus#432 added initial support for VALUE=DATE preservation, but some edge cases still failed with rrule-temporal 1.4.2+ strict RFC5545 validation. Additional fixes: - Strip time component from UNTIL when DTSTART is DATE-only - Ensure UNTIL has UTC 'Z' suffix for DATE-TIME events - Convert non-UTC UNTIL to UTC when DTSTART has TZID - Embed DTSTART;VALUE=DATE in rruleString for proper validation

…al 1.4.2+ (#433) * chore: update rrule-temporal to v1.4.5 * fix: complete UNTIL/DTSTART value type normalization for rrule-temporal 1.4.2+ PR #432 added initial support for VALUE=DATE preservation, but some edge cases still failed with rrule-temporal 1.4.2+ strict RFC5545 validation. Additional fixes: - Strip time component from UNTIL when DTSTART is DATE-only - Ensure UNTIL has UTC 'Z' suffix for DATE-TIME events - Convert non-UTC UNTIL to UTC when DTSTART has TZID - Embed DTSTART;VALUE=DATE in rruleString for proper validation * chore: filter orphaned TZID segments when extracting RRULE string When the internal rule string contains DTSTART;TZID=..., splitting on semicolons produces an orphaned TZID=... segment. This segment is now filtered out along with DTSTART and VALUE= for cleaner RRULE syntax. Note: rrule-temporal tolerates these extra segments, so this is a code quality improvement rather than a bug fix.

KristjanESPERANTO mentioned this pull request Jan 24, 2026

[core] refactor: extract and centralize HTTP fetcher MagicMirrorOrg/MagicMirror#4016

Merged

coderabbitai bot reviewed Jan 24, 2026

View reviewed changes

ical.js Show resolved Hide resolved

KristjanESPERANTO force-pushed the preserve branch from ac46ae6 to 55f8419 Compare January 24, 2026 01:55

rejas mentioned this pull request Jan 26, 2026

Update node-ical and support it's rrule-temporal changes MagicMirrorOrg/MagicMirror#4010

Merged

jens-maus merged commit df1c2fc into jens-maus:master Jan 26, 2026
16 checks passed

KristjanESPERANTO deleted the preserve branch January 28, 2026 09:59

KristjanESPERANTO mentioned this pull request Jan 28, 2026

fix: complete UNTIL/DTSTART value type normalization for rrule-temporal 1.4.2+ #433

Merged

coderabbitai bot mentioned this pull request Feb 20, 2026

refactor: leverage Temporal across the codebase - simplify timezone internals #462

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

fix: preserve VALUE=DATE in DTSTART for RRULE parsing#432

fix: preserve VALUE=DATE in DTSTART for RRULE parsing#432
jens-maus merged 1 commit intojens-maus:masterfrom
KristjanESPERANTO:preserve

KristjanESPERANTO commented Jan 24, 2026 •

edited by coderabbitai bot

Loading

Uh oh!

coderabbitai bot commented Jan 24, 2026 •

edited

Loading

Walkthrough

Changes

Sequence Diagram(s)

Estimated code review effort

Possibly related PRs

Poem

Uh oh!

coderabbitai bot left a comment

Uh oh!

Uh oh!

KristjanESPERANTO commented Jan 26, 2026

Uh oh!

jens-maus commented Jan 26, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Uh oh!

Conversation

KristjanESPERANTO commented Jan 24, 2026 • edited by coderabbitai bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Problem

Solution

Testing

Impact

Summary by CodeRabbit

Uh oh!

coderabbitai bot commented Jan 24, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Changes

Sequence Diagram(s)

Estimated code review effort

Possibly related PRs

Poem

Uh oh!

coderabbitai bot left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

KristjanESPERANTO commented Jan 26, 2026

Uh oh!

jens-maus commented Jan 26, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

KristjanESPERANTO commented Jan 24, 2026 •

edited by coderabbitai bot

Loading

coderabbitai bot commented Jan 24, 2026 •

edited

Loading