Subtract a year or 12 months from current date i.e. today()

[Ayub]

1. What is the problem? Be very detailed.

I am trying to subtract 12 months from current date in "calculate", however unsure of correct format.

2. What app or server are you using and on what device and operating system? Include version numbers.

ODK Collect, XLSForm

3. What you have you tried to fix the problem?

Have reviewed following for two dates subtraction:

Date subtraction is not working in a specific case

Hi @ARIF_AZAD_KHAN I haven't tested the forms, but looking at the definitions, the only differences between the two forms are that the following variables are readonly: date_default_converted week_duration visit_is_applicable For easier comparison, I'd suggest you use a consistent template. At the moment only one of the versions has the constraint field. I hope this helps! Best, Andrea

However, it is not exactly what I am looking for

Any help / guidance would be appreciated!

[Andrea_Martin]

Hi @Ayub

I think you could try subtracting the number of days (365). Useful functions are here

Form Operators and Functions

I suggest you also check this post as it might have some relevant information

Calculate date with number

I find it easier to reason about the year and the month/day separately: concat(int(format-date(today(), ‘%Y’)) + (50-${age}), format-date(today(), ‘%m%d’)) That would be the correct expression if the service was provided today. You probably need to use the service date both to calculate the age and the components of the expiration date. To compute a date N weeks from now: format-date(date(decimal-date-time(today())+(N * 7)), ‘%Y%m%d’) Same as above, you'll need to use the service date rathe…

Best,
Andrea

[Ayub]

Thanks @Andrea_Martin , @LN post helped, for subtracting a month, I used a week instead i.e. minus 4 weeks / 28 days like below to subtract a month:

format-date(date(decimal-date-time(today())-(4 * 7)), ‘%b, %Y’)

However, is there still anyway to minus a whole month through helper functions i.e. not going at days or weeks level?

[Andrea_Martin]

Hi Ayub,

I guess you are already aware about this, but you can also directly enter the number of days you want to subtract (e.g. standard number of days per month (30.4), or 365.25 for year)
format-date(date(decimal-date-time(today())-30.4), ‘%b, %Y’)

But I'm not sure if there a way to

@Ayub

to minus a whole month through helper functions i.e. not going at days or weeks level?

[Ayub]

Hi @Andrea_Martin,

As suggested, I believe going with days is the best option then!

Thanks!