I’ve long thought (but never practiced for some reason) that a dropdown menu that is dynamically generated and only contains one item, should automatically select that item. This would opposed to the typical approach that I’ve observed where a blank entry is made at the top and you still have to interact with the menu to make the single available selection.
An example is when I login to my online banking and select ‘View Paper Statements’. I’ve only got one account so the next step in the process is to present me with a dropdown where I have to select that single account to proceed. In this case, by implementing the solution above, it would take one less click to select the account and proceed to viewing it. Even better in this case would be to eliminate the dropdown menu step altogether and go right to the statement.
Can you think of a case where auto-select of a single item would produce undesirable results?
Yes – any case where the user has the option not to select any option.
In your bank account example, pre-selecting the only value makes sense. But if you have e.g. some kind of form where users can provide voluntary information, they will need the possiblity to leave that field blank or otherwise give a possible incorrect answer.
So it really should depend on the nature of the data in that dropdown whether pre-selection is a good idea or not.