Is there a way to edit check a field

Al,

Tap Forms does not currently provide for data entry validation, which I think is what you’re looking for. The best you can do for now, as far as I can tell, would be to include some additional calculation field(s) that can do some error checking and display “ERROR” or “” depending on the outcome.

Unfortunately, the IF(X,Y,Z) function in Tap Forms is very limited: it only tests for whether the value X is not zero (return Y) or equals zero (return Z). So nothing like in Excel, where you could use a formula such as: IF(OR(DATE<DATE_LIMIT_LOW,DATE>DATE_LIMIT_HIGH),”ERROR”,””).

But there are some ugly kludges you can use. Tap Forms provides a SIGN(X) function, which returns a value of -1, 0, or 1 for X<0, X=0, or X>0.

By way of example, here’s how you could determine if a date field “D” is less than a lower limit “LL” (building up to the answer in two steps for clarity):
• SIGN(D-LL) is 1 if D>LL, is 0 if D=LL, is -1 if D<LL
• SIGN(D-LL)+1 is 2 if D>LL, is 1 if D=LL, is 0 if D<LL

So that last version can be used in an IF statement to test if the date is strictly less than the lower limit: IF(SIGN(D-LL)+1,””,”ERROR”).

But you want to test if the value is between two limits. Extending the thought, you could create a similar expression to test the date D against the upper limit UL, that would yield the value of either 2 or 1 if D <= UL and 0 if D>UL.

You can then test for both conditions simultaneously by multiplying the two functions together. The product will be either 1, 2, or 4 (it doesn’t matter) if and only if the date lies between the two limits, and 0 if outside the two limits. Then stick that in your IF statement, and you’re there.

I told you it was ugly!

— Mike

Hmmm. So X doesn’t have to be a numerical expression, but can also be a logical expression that can be resolved as TRUE or FALSE? And the symbol “&” functions as the logical AND operator? Are there corresponding OR, XOR, and NOT operators as well?

All this is very good. I think the documentation for IF(X,Y,Z) needs to be updated to reflect all this.

Thanks,
Mike

Apologies if this is thread-hijacking but I have a related question: Is there any way to check if a Photo field is empty? I assume no since the Photo fields do not appear in the field list and manually typing “form name::field name” doesn’t work either.

Thanks, Mike. I have a field like that already but I’m trying to catch data entry errors, since humans are not 100% error free! I’ve designed several nested IF statements for other fields that have been very helpful and was hoping to extend the functionality to the photo field…since if a record doesn’t have a photo then there is no receipt.