similar code in several methods

Question

I have method which checks period and return schedules:

public IEnumerable<EventSchedule> GetSchedulesForPeriod(PeriodEvent period, string tab = "")
        {
            switch (period)
            {
                case PeriodEvent.Today:
                    return GetTodaySchedules(tab);

                case PeriodEvent.Tomorrow:
                    return GetTomorrowSchedules(tab);

                case PeriodEvent.Week:
                    return GetWeekSchedules(tab);

                case PeriodEvent.FewWeek:
                    return GetFewWeekSchedules(tab);

                case PeriodEvent.Month:
                    return GetMonthSchedules(tab);
                case PeriodEvent.All:
                    return GetAllFromTodaySchedules(tab);

                default:
                    return GetTodaySchedules(tab);
            }
        }

Consider the GetTodaySchedules and GetTomorrowSchedules:

    private IEnumerable<EventSchedule> GetTodaySchedules(string tab)
{
    var today = DateTime.Now.Date;

    var result = Database.EventSchedules.Where(s => s.RecurrenceStart.Value.Date <= today &&
         s.RecurrenceEnd.Value.Date >= today &&
         s.BaseEvent.IsApproved.Value && !s.IsRemoved.Value &&
         s.BaseEvent.EventsCategories.Any(
         c => c.EventCategory.Name == tab)).ToList();

    return result.Where(s => Evaluator.CheckDate(s, today)).ToList();
} 
private IEnumerable<EventSchedule> GetTomorrowSchedules(string tab)
{
    var today = DateTime.Now.AddDays(1).Date;
    var result = Database.EventSchedules.Where(s => s.RecurrenceStart.Value.Date <= today &&
         s.RecurrenceEnd.Value.Date >= today &&
         s.BaseEvent.IsApproved.Value && !s.IsRemoved.Value &&
         s.BaseEvent.EventsCategories.Any(
         c => c.EventCategory.Name == tab)).ToList();

    return result.Where(s => Evaluator.CheckDate(s, today)).ToList();
}

The similar code have all methods above. How to rewrite it? May be, there is some pattern for this? And, the second, now I want that tab checks only if it filled and introduce new var called placeName (also check if filled):

private IEnumerable<EventSchedule> GetTodaySchedules(string tab, string placeName)
    {
        var today = DateTime.Now.Date;

        var result = Database.EventSchedules.Where(s => s.RecurrenceStart.Value.Date <= today &&
             s.RecurrenceEnd.Value.Date >= today &&
             s.BaseEvent.IsApproved.Value && !s.IsRemoved.Value &&
             s.BaseEvent.EventsCategories.Any(
             c => c.EventCategory.Name == tab) && s.BasePlace.Name).ToList();

        return result.Where(s => Evaluator.CheckDate(s, today)).ToList();
    } 

I don't want to create separate methods for this. What is best way to do this?

Thanks.

Answer 1

You can compose query predicates by applying several where clauses in a row. The predicates must be passed as Expression<Func<T, bool>> for composition.

See LINQ to Entities: Combining Predicates on Microsoft Docs.

Create a general schedules query like this

private IEnumerable<EventSchedule> GetSchedules(
    string tab,
    Expression<Func<EventSchedule, bool>> dateCondition)
{ 
    var result = Database.EventSchedules
        .Where(s => s.BaseEvent.IsApproved.Value &&
            !s.IsRemoved.Value &&
            s.BaseEvent.EventsCategories.Any(c => c.EventCategory.Name == tab))
        .Where(dateCondition)
        .ToList();
    return result.Where(s => Evaluator.CheckDate(s, today)).ToList();
}

And then pass it the appropriate individual date predicate like this

private IEnumerable<EventSchedule> GetTodaySchedules(string tab) {
    var today = DateTime.Now.Date;
    return GetSchedules(
        tab,
        s => s.RecurrenceStart.Value.Date <= today &&
             s.RecurrenceEnd.Value.Date >= today);
}

private IEnumerable<EventSchedule> GetTomorrowSchedules(string tab) {
    var tomorrow = DateTime.Now.AddDays(1).Date;
    return GetSchedules(
        tab,
        s => s.RecurrenceStart.Value.Date <= tomorrow &&
             s.RecurrenceEnd.Value.Date >= tomorrow);
}

Answer 2

Just add another argument to the method:

private IEnumerable<EventSchedule> GetSchedules(string tab, DateTime day)
{
    var result = Database.EventSchedules.Where(s => s.RecurrenceStart.Value.Date <= day &&
         s.RecurrenceEnd.Value.Date >= day &&
         s.BaseEvent.IsApproved.Value && !s.IsRemoved.Value &&
         s.BaseEvent.EventsCategories.Any(
             c => c.EventCategory.Name == tab)).ToList();

    return result.Where(s => Evaluator.CheckDate(s, day)).ToList();
}

And call it with an appropriate value for day. Easy, no?