ColdFusion 9 ORM error: String index out of range: 0

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I just ran into an interesting little issue with my ORM-based ColdFusion 9 site and the explanation was completely surprising to me. I figured I better blog it as I'll probably forget in 3 weeks and Google it to find the answer. The issue cropped up after I had just added some content (a panel) that was saved into a parent object (a page). After the panel was saved and I went to a script that worked with the page object, I began to get this error:

Message: String index out of range: 0
Type: java.lang.StringIndexOutOfBoundsException

My first thought was some kind of simple string error. Perhaps I was doing a left() on a value I assumed had a certain number of characters and for whatever reason the field was blank. However, I narrowed it down to a bit of code that looked like this:

<cfset panels = page.getPanels()> <cfloop index="p" array="#panels#"> <cfoutput>#p.getName()#<br/></cfoutput> </cfloop>

At first I thought - perhaps one of the objects in the array was null. But then the error would have probably been a NPE. Then to make it weirder, when I changed to simply dumping my panels, I still got the error. Then it got even more weird. I discovered I couldn't even do an arrayLen() on the array. Ok, so what the heck, right? I then turned to my entity definition to see if something there would make sense. Here is the panels property within my page object:

property name="panels" fieldType="one-to-many" cfc="panel" fkcolumn="pageidfk" singularname="panel" orderby="area,position" cascade="delete";

Take note of the orderby. I did a quick SQL dump on the panel records and noticed that for the object I just made, area was blank. I wrote a quick bit of SQL to set it to a value and my error went away. Now - let's make this even more odd. In my attempt to recreate this bug, I reset area to null. Get this - the error didn't return. I had to set area to a blank string in order for the error to occur. If I read this right, it means that if you do an orderby on a column and the column can be blank, you will get an error.

That seems unusual to me. I mean if you are going to sort, I would assume everything has values in it, but SQL itself has no problem sorting data with blank values (not nulls) in them. When I just did a sort on it in my editor it simply treated the empty value as coming before A. Not ideal - but no error.

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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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