Improve default date format of BitDatePicker (#8013)

[msynk]

closes #8013

Summary by CodeRabbit

• Refactor
  • Centralized date and time formatting and parsing pattern selection in DatePicker for improved consistency.
  • Enhanced time picker with better support for configurable time format options (12-hour and 24-hour).
  • Improved default date pattern handling to include time portion when time picker is enabled.

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Walkthrough

BitDatePicker refactors date/time format handling by introducing a centralized GetDefaultDateFormat() helper method. This helper encapsulates Mode-based date pattern selection and extends it to append time formatting when ShowTimePicker is enabled, supporting both 12-hour and 24-hour formats. Both parsing and formatting methods now delegate to this helper for consistency.

Changes

Date/Time Format Pattern Centralization

Layer / File(s)

Summary

Date/time format pattern helper and integration src/BlazorUI/Bit.BlazorUI/Components/Inputs/DatePicker/BitDatePicker.razor.cs

New GetDefaultDateFormat() helper centralizes the date format pattern selection logic previously scattered across TryParseValueFromString and FormatValueAsString. The helper computes the default pattern from Mode (month vs. short date) and appends a time component when ShowTimePicker is enabled (12h or 24h based on TimeFormat). Both parsing and formatting methods now use this helper, replacing the previous inline Mode-dependent ternary logic.

🎯 2 (Simple) | ⏱️ ~10 minutes

🐰 A format helper hops in,
No more scattered patterns to flip,
Dates dance with their time,
In a rhythm so prime,
One helper to rule them all—hop! ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the main change: improving the default date format of BitDatePicker to include time display when ShowTimePicker is enabled.
Linked Issues check	✅ Passed	The PR successfully addresses issue #8013 by implementing logic to display selected time in the input when ShowTimePicker is true, as demonstrated by the GetDefaultDateFormat() helper that extends patterns to include time.
Out of Scope Changes check	✅ Passed	All changes are scoped to the BitDatePicker date formatting logic and directly support the objective of displaying time when ShowTimePicker is enabled.

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Actionable comments posted: 1

🧹 Nitpick comments (1)

src/BlazorUI/Bit.BlazorUI/Components/Inputs/DatePicker/BitDatePicker.razor.cs (1)

775-791: 💤 Low value

Consider using culture-specific time patterns for better internationalization.

The time patterns "hh:mm tt" and "HH:mm" are hardcoded and may not align with all culture preferences. While these patterns are standard and consistent with BitCircularTimePicker, consider using the culture's ShortTimePattern or constructing patterns based on the culture's time formatting conventions for better i18n support.

Example approach:

var timePattern = TimeFormat == BitTimeFormat.TwelveHours 
    ? _culture.DateTimeFormat.ShortTimePattern 
    : "HH:mm";

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In
`@src/BlazorUI/Bit.BlazorUI/Components/Inputs/DatePicker/BitDatePicker.razor.cs`
around lines 775 - 791, GetDefaultDateFormat currently appends hardcoded time
patterns; change it to use the culture's time pattern(s) so the output respects
localization: when ShowTimePicker is true, use
_culture.DateTimeFormat.ShortTimePattern (or derive a 12/24-hour pattern from
it) instead of the literal "hh:mm tt"/"HH:mm", keeping the
Mode/BitDatePickerMode.MonthPicker branch and existing pattern composition logic
intact; reference GetDefaultDateFormat, _culture, ShowTimePicker, TimeFormat and
BitTimeFormat.TwelveHours when making the change.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In
`@src/BlazorUI/Bit.BlazorUI/Components/Inputs/DatePicker/BitDatePicker.razor.cs`:
- Around line 775-791: GetDefaultDateFormat currently appends hardcoded time
patterns; change it to use the culture's time pattern(s) so the output respects
localization: when ShowTimePicker is true, use
_culture.DateTimeFormat.ShortTimePattern (or derive a 12/24-hour pattern from
it) instead of the literal "hh:mm tt"/"HH:mm", keeping the
Mode/BitDatePickerMode.MonthPicker branch and existing pattern composition logic
intact; reference GetDefaultDateFormat, _culture, ShowTimePicker, TimeFormat and
BitTimeFormat.TwelveHours when making the change.

---

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📥 Commits

Reviewing files that changed from the base of the PR and between f66f0fc and 1fa64f3.

📒 Files selected for processing (1)

• src/BlazorUI/Bit.BlazorUI/Components/Inputs/DatePicker/BitDatePicker.razor.cs

[msynk]

@coderabbitai re-review

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---

---

@msynk Thanks for the re-review request! The overall approach is clean and well-structured. Here are a few observations:

---

✅ Positives

• GetDefaultDateFormat() is a clean extraction that eliminates duplication and makes both formatting and parsing consistent.
• The 12h↔24h conversion logic is well-commented and handles the common cases correctly.

---

⚠️ Issues

1. Parsing regression when AllowTextInput + ShowTimePicker are both true

Before this PR, TryParseValueFromString used only ShortDatePattern regardless of ShowTimePicker. Now it uses GetDefaultDateFormat() which includes the time portion when ShowTimePicker is true. Users who rely on AllowTextInput to type a bare date (e.g. 6/12/2026) will now fail to parse because the pattern expects a full 6/12/2026 2:30 PM string.

Consider falling back to the date-only pattern when the time-including parse fails:

protected override bool TryParseValueFromString(string? value, [MaybeNullWhen(false)] out DateTimeOffset? result, [NotNullWhen(false)] out string? validationErrorMessage)
{
    if (value.HasNoValue()) { result = null; validationErrorMessage = null; return true; }

    var pattern = DateFormat ?? GetDefaultDateFormat();

    if (DateTime.TryParseExact(value, pattern, _culture, DateTimeStyles.None, out DateTime parsedValue) is false
        && ShowTimePicker
        && DateFormat is null)
    {
        // Fallback: try parsing without the time portion
        var dateOnlyPattern = Mode == BitDatePickerMode.MonthPicker
            ? _culture.DateTimeFormat.YearMonthPattern
            : _culture.DateTimeFormat.ShortDatePattern;
        DateTime.TryParseExact(value, dateOnlyPattern, _culture, DateTimeStyles.None, out parsedValue);
    }
    // ...
}

---

2. Replace("t", "") in AM/PM removal is fragile

return shortTimePattern.Replace('h', 'H').Replace("t", "").Trim();

This removes every occurrence of the character t. While ShortTimePattern in .NET cultures only uses t/tt for the AM/PM designator, this would silently corrupt patterns from any culture that includes a literal t (e.g. a hypothetical "HH't'mm" separator). A more targeted replacement is safer:

return Regex.Replace(shortTimePattern.Replace('h', 'H'), @"\s*t+\s*", "").Trim();
// or simpler:
return shortTimePattern.Replace('h', 'H').Replace("tt", "").Replace("t", "").Trim();

---

3. Contains('h') for 12-hour detection can be confused by quoted literals

var isCulture12Hours = shortTimePattern.Contains('h');

A pattern like "HH'h'mm" (used in some French locale variants as "14h30") would be misidentified as 12-hour. While this is rare in ShortTimePattern, it's worth noting. A more robust check would verify that h appears outside of single-quoted literals.

---

Minor nit

In GetTimePattern(), when converting 24h→12h, the AM/PM separator isn't adjusted to match the culture's conventions — it always appends " tt". For RTL cultures or cultures where AM/PM comes before the time, this may produce an awkward format. This is a low-priority concern since tt in .NET will use the culture's actual AM/PM strings.

---

Overall this is a solid improvement that addresses the core feature request. Item #1 (parsing regression) is the most impactful and worth addressing before merge.

[msynk]

@coderabbitai re-review

[msynk]

@coderabbitai re-review

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---

---

@msynk All three issues raised in the previous review have been addressed — the implementation is clean and production-ready. Here's a quick summary of what changed:

---

✅ All Issues Resolved

#	Issue	Status
1	Parsing regression with AllowTextInput + ShowTimePicker	✅ Fixed — fallback to date-only pattern added with proper guard (parsed is false && DateFormat is null && ShowTimePicker)
2	Fragile Replace("t", "") could corrupt quoted literals	✅ Fixed — new RemoveSpecifier() iterates character-by-character, skipping single/double-quoted segments entirely
3	Contains('h') false positive on quoted literals like 'h'	✅ Fixed — new HasSpecifier() applies the same quote-aware traversal

---

Minor edge case (non-blocking)

The HasSpecifier / RemoveSpecifier helpers treat a pair of consecutive apostrophes '' (escaped literal apostrophe in .NET format strings) as an "open → immediately close" quote block, rather than a literal ' character. However, .NET's ShortTimePattern never uses '' in practice, so this has zero real-world impact and is not worth complicating the code over.

---

Overall this is a solid, well-structured improvement. LGTM 🚀

[approve]

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---

@msynk The code is unchanged from the last reviewed revision — all three previously raised issues remain properly resolved:

1. ✅ Parsing fallback for AllowTextInput + ShowTimePicker is in place.
2. ✅ Quote-aware RemoveSpecifier handles the t/tt removal safely.
3. ✅ Quote-aware HasSpecifier prevents false positives on quoted literals like 'h'.

LGTM 🚀

[approve]

[msynk]

@coderabbitai re-review

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---

@msynk The code is identical to the previously reviewed and approved revision — no new changes detected. All three originally raised issues remain properly resolved:

1. ✅ Parsing fallback for AllowTextInput + ShowTimePicker is in place.
2. ✅ Quote-aware RemoveSpecifier handles t/tt removal safely.
3. ✅ Quote-aware HasSpecifier prevents false positives on quoted literals.

LGTM 🚀

[approve]