Add UTC-safe DateTime helper functions + support for UTC DateTime fields to avoid timezone conversion issues

3

📌 Description / Problem

 

In Mendix, standard DateTime helper functions like beginOfWeek() can return incorrect results in applications that intentionally store and process timestamps in UTC, because the outcome depends on runtime/user timezone localization.

 

This becomes critical when a UTC DateTime is close to midnight.

 

Real example

• Timestamp: Sunday 23:30 UTC

• In CET/CEST, this instant may be interpreted as Monday

• Result: beginOfWeek() may return a different week than expected for a system that must calculate week boundaries strictly in UTC.

 

👉 This makes weekly grouping, reporting, and planning calculations unreliable in UTC-based systems.

 

🎯 Why this matters (Use cases)

This impacts key enterprise use cases such as:

• ✅ Weekly KPIs and reporting (dashboards, Power BI, analytics)

• ✅ Planning and scheduling logic (weekly planning, capacity horizons)

• ✅ Calculation engines and backend automation jobs relying on consistent periods

• ✅ Integrations with ERPs/APIs that exchange timestamps in UTC

• ✅ Multi-country / multi-timezone applications where each user has a different offset

When an application chooses UTC to ensure consistency, the current behavior forces period calculations to depend on local timezone shifts, which defeats the purpose.

 

✅ Requested Improvement (Proposal)

 

1) Add built-in UTC-safe helper functions

Add a standard set of UTC-safe functions that compute boundaries strictly in UTC, without applying localization/timezone conversion:

• beginOfDayUTC(DateTime)

• endOfDayUTC(DateTime)

• beginOfWeekUTC(DateTime)

• endOfWeekUTC(DateTime)

• beginOfMonthUTC(DateTime)

• endOfMonthUTC(DateTime)

Optionally (useful for reporting/UI scenarios):

• ClientUtcOffsetHours() (informational helper)

• FormatClientDateOnlyToString(DateTime)

• FormatClientDateOnlyToStringUTC(DateTime)

•  

2) Support a “UTC DateTime” attribute type (or flag) for entities

It would be very valuable to have a way to define a DateTime attribute as explicitly UTC-based, for example:

• A new attribute type like DateTimeUTCor

• A property/flag on DateTime attributes such as Store/Interpret as UTC (no localization)

This would prevent many subtle bugs caused by implicit timezone conversion in:

• database reads/writes

• microflow calculations

• reporting queries

• integrations

In short: the platform should allow developers to express the intent clearly:✅ “This timestamp represents an absolute UTC moment and must not be localized.”

 

🛠 Current workaround (what we implemented)

As a temporary solution, we implemented these as custom Java Actions to ensure correct UTC calculations:

• beginOfDayUTC

• endOfDayUTC

• beginOfWeekUTC

• endOfWeekUTC

• beginOfMonthUTC

• endOfMonthUTC

• ClientUtcOffsetHours

• FormatClientDateOnlyToString

• FormatClientDateOnlyToStringUTC

This works, but we strongly believe this should be part of Mendix standard capabilities, since it affects many real projects using UTC for integrations, reporting, and calculation engines.

 

✅ Value for the Mendix ecosystem

Adding this to the platform would provide:

• Fewer hard-to-reproduce timezone bugs

• Cleaner projects (no need for custom Java Actions)

• Better support for enterprise/industrial use cases

• More reliable reporting and planning engines

• Predictable behavior in global deployments

asked 2026-01-21

0 answers