"Chris Angelico" <ros...@gmail.com> wrote in message news:CAPTjJmo+fWsCD3Lb6s+zmWspKzzk_JB=pbcvflbzjgcfxvm...@mail.gmail.com... > On Thu, Jun 13, 2013 at 7:32 PM, Frank Millman <fr...@chagford.com> wrote: >> I am talking about what I call 'field-by-field validation'. Each field >> could >> have one or more checks to ensure that the input is valid. Some can be >> done >> on the client (e.g. value must be numeric), others require a round-trip >> to >> the server (e.g. account number must exist on file). Some applications >> defer >> the server-side checks until the entire form is submitted, others perform >> the checks in-line. My preference is for the latter. > > It's not either-or. The server *MUST* perform the checks at the time > of form submission; the question is whether or not to perform > duplicate checks earlier. This is an absolute rule of anything where > the client is capable of being tampered with, and technically, you > could violate it on a closed system; but it's so easy to migrate from > closed system to diverse system without adding all the appropriate > checks, so just have the checks from the beginning. >
In my case, it is either-or. I do not just do field-by-field validation, I do field-by-field submission. The server builds up a record of the data entered while it is being entered. When the user selects 'Save', it does not resend the entire form, it simply sends a message to the server telling it to process the data it has already stored. > In terms of software usability, either is acceptable, but do make sure > the user can continue working with the form even if there's latency > talking to the server - don't force him/her to wait while you check if > the previous field was valid. I know that seems obvious, but > apparently not to everyone, as there are forms out there that violate > this... > I plead guilty to this, but I am not happy about it, hence my original post. I will take on board your comments, and see if I can figure out a way to have the best of both worlds. Frank -- http://mail.python.org/mailman/listinfo/python-list
