In a web application I work on, I have been asked to change an existing 'Owner' field from being free-form to accept only predefined values from a list.

Sometimes that list can be manually configured by an administrator, and sometimes it can be retrieved from an LDAP search based on configuration.

I'm trying to figure out the best way to display this as an option, and a drop-down comes to mind as appropriate if the number of options is small (< 20), but if it's 50 or 100, or even 200, I'm not sure how to display that properly.

My question is: is it confusing to display different controls depending on the number of options?

That is, can I do something like this

  • Fewer than 50 options --> show a drop down
  • 50 options or more --> Show a text box with Ajax autocomplete

or would that be confusing to a user?

Am I going about this the wrong way? Should I just limit the number of options available and always display the drop down?

2 Answers 2


Yes - It would be confusing. I would recommend to use a simple text field with auto-suggest functionallity. That way you don't have to worry about switching controls based on number of items.

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The only problem with it, in terms of user experience, is that the user has to know some part of what to put into the field. At least the first letter of a first name or a last name. And because of that it's not possible to see all options. But opposed to use a too long drop-down - this is a better option.

  • 2
    My concern with such autocomplete fields is that it might look like the suggestions you show are the only ones available. This was mentioned in an AlertBox article "Although helpful, search suggestions can also be limiting; users often view the drop-down as a mini-SERP and assume that it lists everything the site carries. Thus, if something isn't included in the search suggestions, users might never bother to search for it."
    – JonW
    Commented Mar 20, 2013 at 14:26
  • @JonW This is exatly my interpertation of the problem. Either an Administrator makes changes (presumably back-end, structured taxonomy list editing) or it's connected to an Active Directory hosting users (connected by LDAP). In both cases it's a controlled vocabulary unable for users to edit and make their own names. Or did I miss something? Commented Mar 20, 2013 at 14:33
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    Perhaps to ensure that the users know there are more results (instead of treating the ~5 shown as a mini-SERP) you could also have a line at the bottom of the suggestions list saying "+73 more matches". The only problem is that users might then try clicking on that to see the listing.... Commented Mar 20, 2013 at 15:11
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    @BennySkogberg, you are correct. It's an unmodifiable list. I like the bubble approach, and presumably I can figure out a way to display all the results if the number of results are small.
    – Shawn D.
    Commented Mar 20, 2013 at 18:57

You should keep the UX as consistent as possible by using 1 UI control which can scale.

What about nesting the options inside a mega menu accessible on click/tap? You could use a textfield with autocomplete at the top to help users to refine/highlight the matching options within this mega menu

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