Calculate the number of days in a month based on a date

[johnyttan]

Hi guys, let's say I pick a date from Date picker in Power Apps. Based on the date selected, how can I automatically calculate the number of working days (excluding Sunday) in that particular month? 

For example, I pick 11th October 2021, and I get 26 days for the month of October 2021.

I am able to do so using the EOMONTH and NETWORKDAYS.INTL functions in Excel but seems like there isn't a direct function to be used in Power Apps.

[StalinPonnusamy]

Hi @johnyttan 

• StartDates is the Date Picker (In this Example)
• The system will not count Sunday
• Set the Text property of Label Control to

With(
    {
        LastDate: DateAdd(
            DateAdd(
                Date(
                    Year(Now()),
                    Month(Now()),
                    1
                ),
                1,
                Months
            ),
            -1,
            Days
        )
    },
    If(
        StartDates.SelectedDate = LastDate,
        Sum(
            If(
                Weekday(StartDates.SelectedDate) = 1,
                0,
                1
            )
        ),
        Sum(
            ForAll(
                Sequence(
                    DateDiff(
                        StartDates.SelectedDate,
                        LastDate,
                        Days
                    ),
                    0,
                    1
                ),
                If(
                    Weekday(
                        DateAdd(
                            StartDates.SelectedDate,
                            Value
                        )
                    ) = 1,
                    {DayCount: 0},
                    {DayCount: 1}
                )
            ),
            DayCount
        )
    )
)

[johnyttan]

Hi @StalinPonnusamy , thanks for replying.

I've copied your functions and replaced StartDates with DatePicker but the outcome shows the remaining of days towards the end of the month, and it includes Sunday.

For example, I pick 26th October 2021 it returns 5 and when I pick 27th October 2021 it returns 4. 

What I would like to achieve is that whichever date that I pick in October 2021, it will return 26 days (exclude Sundays).

[StalinPonnusamy]

Hi @johnyttan 

With(
    {
        StartDate: Date(
            Year(StartDates.SelectedDate),
            Month(StartDates.SelectedDate),
            1
        ),
        LastDate: DateAdd(
            DateAdd(
                Date(
                    Year(StartDates.SelectedDate),
                    Month(StartDates.SelectedDate),
                    1
                ),
                1,
                Months
            ),
            -1,
            Days
        )
    },
    If(
        StartDate = LastDate,
        Sum(
            If(
                Weekday(StartDate) = 1,
                0,
                1
            )
        ),
        Sum(
            ForAll(
                Sequence(
                    DateDiff(
                        StartDate,
                        LastDate,
                        Days
                    ),
                    0,
                    1
                ),
                If(
                    Weekday(
                        DateAdd(
                            StartDate,
                            Value
                        )
                    ) = 1,
                    {DayCount: 0},
                    {DayCount: 1}
                )
            ),
            DayCount
        )
    )
)

[RandyHayes]

@johnyttan 

You can create your own function using a component in your app if you find you need to do these calculations often.

Also, I would advise a formula more conducive to how PowerApps is designed rather than a programmatic design.

Here are the steps:

1) Create a new Component in your app.  Name it what you want (I will call it cmp_Functions)

2) Make sure you have the  Enhanced component properties feature turned on in the settings.

3) In your Component, create a new custom property.

    a) Call it DaysOfMonth

    b) Set the Property Type to Output

    c) Set the Data type to Number

    d) Create a new parameter.  Call it MonthDate and set the Data Type to Date and time, also set the parameter to Required. Then save the parameter.

    e) Create another new parameter.  Call it WorkDays and set the Data Type to Table. Do not make it required.  Save the parameter.

    f) Then Save the property.

4) In the property chooser in the formula bar, select the WorkDays property/parameter and set the formula to  [0,1,2,3,4,5,6]  (this will be all days of the week - the default)

5) Select the DaysInMonth property and change the formula to: 

With({_monthStart: Date(Year(MonthDate), Month(MonthDate), 1)},
    CountRows(
        Filter(
            ForAll(
                Sequence(DateDiff(_monthStart, DateAdd(_monthStart, 1, Months))-1, 0),
                Weekday(DateAdd(_monthStart, Value, Days), StartOfWeek.MondayZero)
            ),
            Value in WorkDays
        )
    )
)

And you are done with the Component.

Now, insert the component in your app screen.  At this point you can use the component function any place in your app.

For example, if you want to see the total number of days in a selected month, then set a label text property to:

   cmp_Functions.DaysInMonth(yourDatePicker.SelectedDate)

This will show the total number of days in the month.

To show the total number of days in a month and exclude Sundays, then set your Text property formula to:

   cmp_Functions.DaysInMonth(yourDatePicker.SelectedDate, [0,1,2,3,4,5])

Excluding Sat and Sun, then the formula is:

   cmp_Functions.DaysInMonth(yourDatePicker.SelectedDate, [0,1,2,3,4])

Note, the weekdays are set to Monday as 0 in the main formula.  So, Monday is 0 and the days count up from that.

I hope this is helpful for you.

[johnyttan]

@StalinPonnusamy 

I've tested the formula across a few months and only October 2021 gives the correct output. The rest of the months have 1 day lesser than the actual days, as shown in the table below. Is this due to the Datediff function when the last date substracts the first date of the month? For example when 31st - 1st it gives 30 days instead of 31 days in a month.

		Actual Days (Exclude Sunday)	Calculated Days
2021	June	26	25
2021	July	27	26
2021	August	26	25
2021	September	26	25
2021	October	26	26
2021	November	26	25
2021	December	27	26
2022	January	26	25
2022	February	24	23
2022	March	27	26
2022	April	26	25
2022	May	26	25
2022	June	26	25

[johnyttan]

Hi @RandyHayes , thanks for replying with a different approach. However I noticed there's this same issue:

I've tested the formula across a few months and only October 2021 gives the correct output. The rest of the months have 1 day lesser than the actual days, as shown in the table below. Is this due to the Datediff function when the last date substracts the first date of the month? For example when 31st - 1st it gives 30 days instead of 31 days in a month. But if this is the case why does only October 2021 give the correct output?

		Actual Days (Exclude Sunday)	Calculated Days
2021	June	26	25
2021	July	27	26
2021	August	26	25
2021	September	26	25
2021	October	26	26
2021	November	26	25
2021	December	27	26
2022	January	26	25
2022	February	24	23
2022	March	27	26
2022	April	26	25
2022	May	26	25
2022	June	26	25

[StalinPonnusamy · Accepted solution]

Hi @johnyttan 

Fixed the issue.

With(
    {
        StartDate: Date(
            Year(StartDates.SelectedDate),
            Month(StartDates.SelectedDate),
            1
        ),
        LastDate: DateAdd(
            DateAdd(
                Date(
                    Year(StartDates.SelectedDate),
                    Month(StartDates.SelectedDate),
                    1
                ),
                1,
                Months
            ),
            -1,
            Days
        )
    },
    If(
        StartDate = LastDate,
        Sum(
            If(
                Weekday(StartDate) = 1,
                0,
                1
            )
        ),
        Sum(
            ForAll(
                Sequence(
                    DateDiff(
                        StartDate,
                        LastDate,
                        Days
                    ) + 1,
                    0,
                    1
                ),
                If(
                    Weekday(
                        DateAdd(
                            StartDate,
                            Value
                        )
                    ) = 1,
                    {DayCount: 0},
                    {DayCount: 1}
                )
            ),
            DayCount
        )
    )
)

[RandyHayes]

@johnyttan 

It appears that the numbers are correct.  October has 31 days and 5 Sundays - that makes 26.  November has 30 days and 4 Sundays - that makes 26.  December has 31 days and 4 Sundays - that makes 27.

So the formula is correct from what I see for calculating days for the month minus and days you want excluded (Sunday in this case).

What I don't understand is what your calculated days column is...what are you doing there?

[johnyttan]

@RandyHayes 

The Actual Days are the ones that I count manually from calendar, hence the correct ones. 

The Calculated Days are the output from the formula that you posted. Generally 1 day lesser than the correct number for all months except for October 2021.