I have a PowerApps form which asks for several dates. I know the preferred solution is to set IsEditable to false and force users to click the calendar. However one of my fields is the Date of Birth. Expecting a user to click the back arrow a month at a time to choose a date in 1970 is unreasonable.
So I set IsEditable to true, but I of course need to do data validation now. Not just that the date isn't in the future, but also that it's a date at all and not junk like "June" or "Apple" or 99/99/9999.
Plan A, the simplest way to do this would be OnSubmit for a form, or the equivalent for patch. However I hate the user experience or letting the user enter an invalid value, ignoring it, and then throwing an error later. Why not tell the user they are making a mistake while they are making a mistake?
In addition, this solution does not work if your date is optional. DatePicker with junk in it returns blank, so the OnSubmit cannot differentiate between an invalid date and no date.
Plan B, I'll just add some code to the OnChange property of the DatePicker. Except that does not work. If the entered date is not a date, the DatePicker pretends it doesn't exist and does not trigger the OnChange property.
Plan C, I'll setup some code that looks at the DatePicker property of SearchText or Text and does validation on that. Except that does not work, those properties do not exist.
Plan D, ditch the DatePicker entirely, use a TextInput control. This is a viable option. If you're short on time, just do this. There are a lot of reasons I don't like this though. It's crazy to me that the best option to enter a date is to not use DatePicker. It does not allow the user to use the calendar. It doesn't give the visual indications of it being a date field.
Plan E, use both a TextInput and a DatePicker field, tie them together. If this sounds overly complicated it is, but it's the best solution I could come up with. I put the TextInput above the DatePicker, covering most of the DatePicker control except for the Calendar button on the right. Set the default value for both controls to a varDate (can be Blank() or a valid date). Set the OnChange for the DatePicker to Set(varDate,Self.SelectedDate). This will only trigger if they click the calendar icon to change the date since they cannot get to the box to type in it.
Then in the TextInput in OnChange do the fancy date validation. You can google to find formulas for this. Some people use impressive OnMatch formulas. I opted for a simple:
Set(varDate, IfError( DateValue(Self.Text),Blank()));
This works surprisingly well. If anything it's a bit too lenient. You can type in 2 and it will pick 2/1/2001. But it's great for 12 June 04 or 2004/6/12.
The really nice part of this is the user can interact with these two fields like they are one field. They can type a date in, then click the calendar to confirm which day of the week it is for example.
