DateTime extensions

The MADE.Data.Converters.Extensions.DateTimeExtensions class provides extension methods for common date and time calculations. These handle the edge cases that make date arithmetic tedious - month boundaries, week starts, age calculation, and time rounding.

Calculating age with ToCurrentAge

Calculates a person's current age in years from a birth date:

using MADE.Data.Converters.Extensions;

DateTime birthDate = new(1990, 6, 15);
int age = birthDate.ToCurrentAge(); // Correctly handles leap years and month boundaries

This handles the common pitfall of naive age calculation (dividing days by 365.25) by properly accounting for whether the birthday has occurred yet this year.

Period boundaries

These extensions are useful for reporting, filtering, and analytics where you need to query data within a specific time period.

Day boundaries

DateTime now = DateTime.Now;

DateTime startOfDay = now.StartOfDay();  // Today at 00:00:00
DateTime endOfDay = now.EndOfDay();      // Today at 23:59:59.999

Week boundaries

DateTime startOfWeek = now.StartOfWeek();  // Most recent Monday at 00:00:00
DateTime endOfWeek = now.EndOfWeek();      // Coming Sunday at 23:59:59.999

Month boundaries

DateTime startOfMonth = now.StartOfMonth();  // 1st of current month at 00:00:00
DateTime endOfMonth = now.EndOfMonth();      // Last day of current month at 23:59:59.999

Year boundaries

DateTime startOfYear = now.StartOfYear();  // January 1st at 00:00:00
DateTime endOfYear = now.EndOfYear();      // December 31st at 23:59:59.999

Rounding to the nearest hour

var time = new DateTime(2026, 5, 17, 14, 42, 0);
DateTime rounded = time.ToNearestHour(); // 2026-05-17 15:00:00

Day suffix

Returns the ordinal suffix for the day of the month:

DateTime date = new(2026, 5, 1);
string suffix = date.ToDaySuffix(); // "st"
// Useful for formatting: "May 1st", "May 2nd", "May 3rd", "May 4th"

Setting the time component

Overrides the time portion of a DateTime while keeping the date:

DateTime date = DateTime.Today;

// Set to specific time
DateTime withTime = date.SetTime(14, 30);        // 2:30 PM
DateTime precise = date.SetTime(14, 30, 45);     // 2:30:45 PM
DateTime exact = date.SetTime(14, 30, 45, 500);  // 2:30:45.500 PM

Practical example: building a date range query

These extensions compose naturally for common data access patterns:

public async Task<IEnumerable<Order>> GetThisWeeksOrdersAsync()
{
    var weekStart = DateTime.UtcNow.StartOfWeek();
    var weekEnd = DateTime.UtcNow.EndOfWeek();

    return await dbContext.Orders
        .Where(o => o.CreatedDate >= weekStart && o.CreatedDate <= weekEnd)
        .ToListAsync();
}