ColdFusion 9 fixes arrayIsDefined

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I coulda sworn I had blogged this earlier but it didn't show up on my search. This just came up in a meeting at work so I thought I'd share. ColdFusion 8 added the arrayIsDefined function. As you can probably guess it let's you check to see if an array has a value at a certain position. However, it had one pretty silly drawback. If your array was had a size of 10 and you checked position 11, you would get an error. Therefore to really check to see if a certain array position existed, you had to use this:

<!--- assume array is called arr and N is the position you want to check ---> <cfif arrayLen(arr) gte n and arrayIsDefined(arr, n)>

ColdFusion 9 though fixes this. So your code can just be:

<!--- assume array is called arr and N is the position you want to check ---> <cfif arrayIsDefined(arr, n)>

Oddly, the docs for arrayIsDefined still insist that you must stay within the bounds of the array. I'm filing a comment now.

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Raymond is a senior developer evangelist for Adobe. He focuses on document services, JavaScript, and enterprise cat demos. If you like this article, please consider visiting my Amazon Wishlist or donating via PayPal to show your support. You can even buy me a coffee!

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Archived Comments

Comment 1 by Ben Nadel posted on 4/6/2010 at 11:36 PM

It would be sweet if this functionality worked with isDefined()... as in isDefined( arr[ n ] ).

Comment 2 by Jody Fitzpatrick posted on 4/7/2010 at 4:55 PM

Awe, com'on now Ben it's like 5 characters more :) I can't wait until ColdFusion has the feature

DoAllTheWorkForMe("ProjectName"); Then your application is done. Can't wait,... can't wait.

Comment 3 by Raymond Camden posted on 4/7/2010 at 4:58 PM

@Jody: If we make things too easy, the PHPers and Ruby dev's will commit suicide out of jealousy.

Comment 4 by Ben Nadel posted on 4/7/2010 at 5:00 PM


Ha ha... but isNull() just *looks* cooler :)

Comment 5 by Raymond Camden posted on 4/7/2010 at 5:02 PM

You aren't cool unless you combine isNull with the trenary operator and DE at the same time.

Comment 6 by Ben Nadel posted on 4/7/2010 at 5:14 PM

Ha ha ha :) Might want to throw an IncrementValue() in there for good measure.

Comment 7 by Raymond Camden posted on 4/7/2010 at 5:44 PM

I smell a Friday contest.

Comment 8 by Ben Nadel posted on 4/7/2010 at 5:46 PM

Ha ha, sweeeet :)

Comment 9 by Ben Cass posted on 4/7/2010 at 8:15 PM

What would really be nice is if there were one function that could check if an element in an array of structs (or other complex objects) exists.

E.g. isDefined("my_array[n].element_foo")

Comment 10 by Raymond Camden posted on 4/7/2010 at 10:41 PM

While it doesn't return a boolean, you can do that with structGet. It will attempt to find the variable based on a complex string path. It will even create stuff. So given your example, if my_array existed, but item N did not, and element_foo did not, it would make it.

structGet - the function no one uses! ;)

Comment 11 by evan posted on 6/25/2010 at 5:22 PM

Hi. Call me crazy, but my CF 9 implementation still seems to include the CF 8 style bug. I had to revert back to using arraylen GTE... Anyone else seen this?

Comment 12 by Raymond Camden posted on 6/28/2010 at 5:08 PM

Um, ok, I'm confused now too. I see the same. I swear this worked. Can anyone else check?

Comment 13 by Raymond Camden posted on 6/28/2010 at 11:21 PM

Turns out I was on crack. I have no idea _why_ I put this blog post up when it really didn't work. I apologize folks.

The good news is that I can confirm it is fixed for CF901. You didn't hear that from me though.

Comment 14 by Ben posted on 4/26/2011 at 9:59 PM

Good lord, thank you! What a pain....