Obtain Dates from Weeknumber

[DevadathanK]

Hi everyone!

Im having a doubt in PowerApps.

I was wondering if we can obtain the starting and ending dates from the weeknumber.

For example
So if the Week number is 10, the starting date should be 01-03-2020 and the ending date should be 07-03-2020. (Considering year as 2020 and the week starts with Sunday.)

Is there a way to find it?

Thank you for the help!!

Regards

(The original post for finding the week numbers - https://powerusers.microsoft.com/t5/Building-Power-Apps/Displaying-only-the-Weeks-of-the-current-mon...)

[WarrenBelz]

Hi @DevadathanK ,

I can start you on this and happy to help if you get stuck.

Firstly the formula (assuming DatePicker1 is your data source) for the current day of the year would be

DateDiff(
    Date(
        Year(DatePicker1.SelectedDate),
        1,
        1
    ),
    DatePicker1.SelectedDate
) + 1

The week number of the date would be

Round(
   ( 
      DateDiff(
         Date(
            Year(DatePicker1.SelectedDate),
            1,
            1
         ),
         DatePicker1.SelectedDate
      ) + 1
   )/7,0
)

You can get the day of the week with

Weekday(DatePicker1.SelectedDate)

So the start of the week date is

DatePicker1.SelectedDate - Weekday(DatePicker1.SelectedDate) +1

Please let me know how you go with this.

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[DevadathanK]

Hey @WarrenBelz,

Firstly, Thank you for trying to help me out 😃

So the input is not actually from a datepicker.

I already have the Week numbers with me. I need the start and end date corresponding to each weeknumber.

[WarrenBelz]

Thanks @DevadathanK ,

That is why I gave you all the formulas - I was not sure how you were doing it. I am not sure how you would reverse engineer the one from the date to the date number, but you could simply collect the 52 possibilities as below at App OnStart and do a Lookup.

ClearCollect(
    colWeekNos,
    {
        WeekNo: 1,
        WeekStart: DateValue("1/1/2020")
    },
    {
        WeekNo: 2,
        WeekStart: DateValue("1/8/2020")
    },
    {
        WeekNo: 3,
        WeekStart: DateValue("1/15/2020")
    },
    {
        WeekNo: 4,
        WeekStart: DateValue("1/22/2020")
    },
    {
        WeekNo: 5,
        WeekStart: DateValue("1/29/2020")
    }
)

Then 

Lookup(
   colWeekNos,
   WeekNo = Value(YourTextBox.Text),
   WeekStart
)

 Please click Accept as solution if my post helped you solve your issue. This will help others find it more readily. It also closes the item. If the content was useful in other ways, please consider giving it Thumbs Up.

[v-yutliu-msft · Accepted solution]

Hi @DevadathanK ,

I'm so glad to meet your issue again.

Since I've answered your last post, let me  started from my previous reply.

Actually, you just need to make a little change from my previous reply.

The previous reply:

Filter(b,Value>=startweek,Value<=endweek)

//get current week num

Try this formula instead:

AddColumns(
       AddColumns(
            AddColumns(Filter(b,Value>=startweek,Value<=endweek),
                       "id",
                       Value-First(Filter(b,Value>=startweek,Value<=endweek)).Value
                       ),  //get the id value based on weeknum
            "startdate",
            DateAdd(Date(Year(Today()),Month(Today()),1),7*id,Days)
                   ),     //get the start date based on id
        "enddate",
        DateAdd(startdate,6,Days)      //get end date based on start date
           )

 Other steps are the same.

Best regards,

[WarrenBelz]

Hi @DevadathanK ,

The response from code guru @v-yutliu-msft is certainly more elegant than mine - tag me if if you want to continue with my logic.

[DevadathanK]

Hi @v-yutliu-msft

As always your logic is amazing. Thank you so much for the advice.

I have made one small change to get the number of days for the first week of a month(because every month wont start with Sunday).

7-(Weekday(Date(Year(Today()),Month(Today()),1)

I added this to the first startdate to get the first enddate of the month and then from the 2nd set, added 6 days to get the end date as you suggested.

---------------------------------------------

Now let me tell you how i made modifications to my application according to your advice from the pervious post,

I was asked to make it so that the Sharepoint List that i used to make the App, could also be used to enter data when needed. So i had to make the 53 columns in the Sharepoint list.

You had showed me how to display the Weeks in a list box. I made it so that when a Week was selected from this list box, an input box for that particular week would be made visible just below the list box.

Since all 53 Datacards are already present in the app, eventho hidden, i used the earlier formula to find the duration of Week 1 and then from Week 2 to Week 53, i used

Set(startdate_1,DateAdd(enddate,1,Days))
Set(endate_1,DateAdd(startdate_1,6,Days))
And so on