You are right. Having (re)read the documentation for re, I find that it is working as advertised. My original regex was wrong. However, I would argue that if the match found by regex.match() is different from the input value, IS_MATCH should return an error. That is, in the IS_MATCH.__call__ definition, "if match:" should be "if match and (value == match.group():". That change would raise an error that would force a user like me to correct a regex that was matching in an unexpected way. I would never want IS_MATCH to silently change data between a form and insertion into a database.
Ken On Feb 2, 9:13 pm, Massimo Di Pierro <[email protected]> wrote: > This is the correct behavio of regular expressions. Anyway, good that > you are pointing this out since others may find it counter intuitive. > > Massimo > > On Feb 2, 6:33 pm, Ken <[email protected]> wrote:> I have been having trouble > with truncation of data from one field of a > > form. The culprit turned out to be the IS_MATCH() validator, which was > > truncating a valid value to return a shorter valid value. I'm not sure > > whether to call this a bug or just unexpected behavior, but if I had > > trouble with it, someone else may. > > > The data in question were spreadsheet-style coordinate values with > > letters for rows and numbers for columns, in the range A1 to J10. > > Initially, I used a validator like IS_MATCH('^[A-J][1-9]|[A-J]10$'). > > This checks first for the two-character combinations A1 to J9, then > > checks for A10 to J10. If I test this in a web2py shell, it accepts > > and returns the two-character combinations, but it accepts and > > truncates any values ending in 10. > > > In [1] : vdtr = IS_MATCH('^[A-J][1-9]|[A-J]10$') > > > In [2] : vdtr('A1') > > ('A1', None) > > > In [3] : vdtr('J1') > > ('J1', None) > > > In [4] : vdtr('A10') > > ('A1', None) > > > In [5] : vdtr('J10') > > ('J1', None) > > > It seems to me that A1 and J1 are not proper matches because the '1' > > does not appear at the end of the validated string. In any case, I am > > surprised that IS_MATCH() would modify a value under any > > circumstances. > > > If I turn the regex around, so that it tests for the three-character > > combinations first, like IS_MATCH('^[A-J]10|[A-J][1-9]$'), then things > > work better. > > > In [6] : vdtr = IS_MATCH('^[A-J]10|[A-J][1-9]$') > > > In [7] : vdtr('A1') > > ('A1', None) > > > In [8] : vdtr('J1') > > ('J1', None) > > > In [9] : vdtr('A10') > > ('A10', None) > > > In [10] : vdtr('J10') > > ('J10', None) > >
