How to output an array to a comma-deliniated string?

Question

I have an array called device, which looks like this (simplified):

label : "Device 1",
exhibits : [{
    item : 1,
    desc : "This is a sample"
},{
    item : 2,
    desc : "This is another sample"
},{
    item : 3,
    desc : "This is a third"
}]

I'm trying to print exhibits neatly for a PDF, so I'm thinking comma-deliniated like this:

1, 2, 3

This is my code:

<cfloop array="#device.exhibits#" index="exhibit">
    #exhibit.item#
</cfloop>

But I get this:

123

Yes, I could manually figure out if there should be commas or not, but is there a better way to do this?

Answer 1

The usual approach is to extract the data first:

<!--- extract the itemNumber of every exhibit --->
<cfset itemNumberList = []>
<cfloop array="#device.exhibits#" index="exhibit">
    <cfset itemNumberList.add(exhibit.itemNumber)>
</cfloop>

And then we transform the extracted data to a comma-separated list (string):

<cfset itemNumberList = arrayToList(itemNumberList, ", ")>

<!--- 1, 2, 3 --->
<cfoutput>#itemNumberList#</cfoutput>

Array-mapping (see Shawn's answer) is a more fancy (readable?) way.