In an application i am designing, there is a form, where the user completes the fields and some of them might remain empty (not filled by the user). Then we have the info page showing all these fields with their data, inserted by the user, but also showing the empty fields.
Is that right from a ux point, or would it be better not to show the empty ones at all?
It depends. Is it important to your users to know whether or not a field is blank? If it is, show the field with a blank value. There is also value in presenting a consistent interface to your users; also, will hiding a variable number of fields throw off the visual aesthetic of your details interface?
There are advantages to hiding blank fields; if your form is long and your users know much of it is optional, you can gain some screen real estate and also eliminate dead space in the interface, potentially allowing your users to scan for the information you need more quickly (of course, the information they need might be in a different place in the screen depending on how many fields are hidden).
When reading a profile, being told what isn't there isn't particularly useful to the average user. So, unless there is some reason that you need to indicate that a field is blank, I would simply not display any empty fields in a profile.
Look at this example, and you decide how much value it adds:
"There isn't a fax number, and there isn't a facebook profile, and there isn't a pinterest profile, and there isn't a middle name, and there isn't a twitter account, and there isn't an age, and …"
We know what there isn't simply by it not being there. We don't need to be explicitly told what there isn't.
Depends on the target audience. If this is for power users, i'd show "Fields not provided by user/empty" (probably collapsed by default) so at least the system is reporting the data correctly. This is especially true when the data is from multiple sources and also way to ensure the system is working properly.
