Reading Calendar Information from Project Files

Overview

Microsoft Project allows associating various calendars with project-level work time, tasks, and resource availability. Aspose.Tasks for .NET provides full support for reading this calendar data from MPP files, including all major versions (2003–2013 and later).

This article explains how to retrieve calendar collections, read detailed calendar configuration (e.g., work weeks), and compute actual working hours between specified dates using the Aspose.Tasks API.

Retrieving Calendar Information

The Project class exposes the Calendars property, which returns a CalendarCollection. This collection holds all calendars defined in the project file.

To verify calendars in Microsoft Project:

1. Open the project file.
2. Navigate to Project > Change Working Time.

The following code demonstrates how to iterate over project calendars and retrieve their metadata.

// Create a project instance
Project project = new Project("RetrieveCalendarInfo.mpp");

// Retrieve Calendars Information
CalendarCollection calendars = project.Calendars;
foreach (Calendar cal in calendars)
{
    if (cal.Name != null)
    {
        Console.WriteLine("Calendar UID : " + cal.Uid);
        Console.WriteLine("Calendar Name : " + cal.Name);

        WeekDayCollection alDays = cal.WeekDays;
        foreach (WeekDay wd in alDays)
        {
            TimeSpan ts = wd.GetWorkingTime();
            if (wd.DayWorking)
            {
                Console.WriteLine(wd.DayType.ToString() + ":");
                Console.WriteLine(ts.ToString());
            }
        }
    }
}

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Reading Work Week Configurations

Calendars in Microsoft Project can define custom work weeks to override default working times. Aspose.Tasks exposes these through the WorkWeek class.

Work weeks can be accessed via the WorkWeeks property on the Calendar object. Each WorkWeek contains metadata about the date range and working times for each day.

Project project = new Project("ReadWorkWeeksInformation.mpp");
Calendar calendar = project.Calendars.GetByUid(3);
WorkWeekCollection collection = calendar.WorkWeeks;

foreach (WorkWeek workWeek in collection)
{
    DateTime fromDate = workWeek.FromDate;
    DateTime toDate = workWeek.ToDate;

    // This data is all about "Details." button you can set special working times for special WeekDay or even make it nonworking
    WeekDayCollection weekDays = workWeek.WeekDays;  
    foreach (WeekDay day in weekDays) 
    {
        // You can further traverse through working times and display these
        WorkingTimeCollection workingTimes = day.WorkingTimes;
    }
}

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Calculating Working Hours Between Dates

To evaluate scheduling feasibility or resource availability, developers may need to compute the total number of working hours between two DateTime values. Aspose.Tasks enables this through two method overloads on the Calendar class:

• GetWorkingHours(DateTime dt)
• GetWorkingHours(DateTime start, DateTime end)

Note: When specifying date ranges, provide full timestamps (hour, minute, second). If the end date is passed without time (e.g., 2025-08-18), it is treated as 00:00:00 and excluded from the interval.

The following example calculates working durations in minutes, hours, and days between two dates.

// Load an existing project
Project project = new Project("New Project.mpp");

// Access Task By Id
Task task = project.RootTask.Children.GetById(1);

// Access Calendar and it's start and end dates
Calendar taskCalendar = task.Get(Tsk.Calendar);
DateTime startDate = task.Get(Tsk.Start);
DateTime endDate = task.Get(Tsk.Finish);
DateTime tempDate = startDate;

// Access resource and their calendar
Resource resource = project.Resources.GetByUid(1);
Calendar resourceCalendar = resource.Get(Rsc.Calendar);

TimeSpan timeSpan;

// Get Duration in Minutes
double durationInMins = 0;
while (tempDate < endDate)
{
    if (taskCalendar.IsDayWorking(tempDate) && resourceCalendar.IsDayWorking(tempDate))
    {
        timeSpan = taskCalendar.GetWorkingHours(tempDate);
        durationInMins = durationInMins + timeSpan.TotalMinutes;
    }
    tempDate = tempDate.AddDays(1);
}
tempDate = startDate;

// Get Duration in Hours
double durationInHours = 0;
while (tempDate < endDate)
{
    if (taskCalendar.IsDayWorking(tempDate) && resourceCalendar.IsDayWorking(tempDate))
    {
        timeSpan = taskCalendar.GetWorkingHours(tempDate);
        durationInHours = durationInHours + timeSpan.TotalHours;
    }
    tempDate = tempDate.AddDays(1);
}
tempDate = startDate;

// Get Duration in Days
double durationInDays = 0;
while (tempDate < endDate)
{
    if (taskCalendar.IsDayWorking(tempDate) && resourceCalendar.IsDayWorking(tempDate))
    {
        timeSpan = taskCalendar.GetWorkingHours(tempDate);
        if (timeSpan.TotalHours > 0)
        {
            durationInDays = durationInDays + timeSpan.TotalDays * (24 / (timeSpan.TotalHours));
        }
    }
    tempDate = tempDate.AddDays(1);
}

Console.WriteLine("Duration in Minutes = " + durationInMins);
Console.WriteLine("Duration in Hours = " + durationInHours);
Console.WriteLine("Duration in Days = " + durationInDays);

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