When programming a tabular application module (i.e., the user mainly enters tabular data into an already laid out table), how would you reject user input for a given cell?
Scenario: the user edits a cell, enters something (text, image, ...), and you want them to notice when they finish editing (for example, press enter) that their entry is not valid for your "format" (in in a broader sense: maybe they entered a string instead of a number, that their record is too long, too short, they include the image while it is unacceptable, ...).
I see two different things:
- You can easily enter them in your format, and you will, but you want them to notice it so that they can change if your hunch is not good enough (for example: they entered "15.47" in the field, which is necessary to be an integer , so your program does this "15").
- You cannot figure out what to do with their recording, and want to tell them that this is not valid.
My question is in particular: what visual display can you offer to inform the user that his input is invalid? Is it advisable to abandon the editing mode or not?
Two things I can imagine:
- use of colors (red background, if invalid, yellow background for my case 1 above)
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