Join Two Arrays in ColdFusion

Question

Is there a built-in way to join two arrays in ColdFusion, similar to JavaScript's array.concat()?

Solution 1

Not really, but guess what, just use Java! :)

<cfset foo = [1,2,3]>
<cfset bar = [4,5,6]>
<cfset foo.addAll( bar )>

reference: Java's Collection Interface API.

source: http://www.aliaspooryorik.com/blog/index.cfm/e/posts.details/post/merging-two-arrays-267

Solution 2

CF10+, use

arrayAppend(array1, array2, true);

https://helpx.adobe.com/coldfusion/cfml-reference/coldfusion-functions/functions-a-b/arrayappend.html

Solution 3

If you're using Railo, you can use ArrayMerge (E.g. <cfset NewArray=ArrayMerge(FirstArray,SecondArray)>).

Solution 4

Its kinda dumb how coldfusion misses many basic functions that one would expect from a scripting language. Here's one I had to write quickly.

<cffunction name="mergeArrays" returntype="array" >
    <cfargument name="array1" type="array" required="true" >
    <cfargument name="array2" type="array" required="true" >

    <cfset arrayResult = arrayNew(1) >
    <cfloop array="#array1#" index="elem">
        <cfset arrayAppend(arrayResult,elem) >
    </cfloop>

    <cfloop array="#array2#" index="elem">
        <cfset arrayAppend(arrayResult,elem) >
    </cfloop>

    <cfreturn arrayResult>
</cffunction>

Solution 5

In CF 10 or Railo 4, you can use the concat() function of the Underscore.cfc library to get a new array that is a concatenation of two other arrays (without modifying the existing arrays). Example cfscript:

newArray = _.concat([1], [2]);

Result:

// newArray == [1, 2]

Using this method to get a new array is a bit cleaner than creating a new array and calling ArrayAppend on it twice.

(Disclaimer: I wrote Underscore.cfc)

View more solutions

Comments

[Henry]

I've added to Adobe's ColdFusion Bug Tracker as feature request at cfbugs.adobe.com/cfbugreport/flexbugui/cfbugtracker/… . Vote it up! :)

[Henry]

ArrayConcat Vs. ArrayMerge Vs ArrayAppend ? Please discuss here: groups.google.com/group/cfml-conventional-wisdom/browse_thre‌​ad/…

[zarko.susnjar]

Oddly enough, underlying Java methods do not work always as expected. I still haven't figure out exactly when and why. I often use Java methods for removing duplicates, joining and sorting Arrays, I remember sometimes it didn't work depending how you create arrays, which operations you perform before calling Java method etc. So pay attention!

[Leigh]

@zarko.susnjar - I know this is an old thread, but the reason for the unexpected results with methods like removeAll, retainAll, etcetera is that the java methods are not as lenient as your typical CF function. They are usually data type sensitive. So "2" (string) and val(2) (number) are considered different values/elements. Unless you are absolutely certain the data types in both arrays match, you are better of using other methods IMO.

[zarko.susnjar]

Of course, if you are not certain about something, always go the safer and proven way.

[John]

+1, It is impressive that you remembered this question and came back two years later to improve it.

[Leigh]

Actually I think you got it from me, haha .. and looking at this thread, I probably got it from @noj's answer and rewrote it in cfscript ;)

[Leigh]

Just keep in mind it is not a complete equivalent as it will a) drop any empty array elements and b) split array values on whatever delimiter is used ,. ie The single value arr[1] ="Doe, John" would become arr[1] = Doe, arr[2] = John.

[Betty Mock]

Leigh, you make a good point. This could be worked around by using a different list delimiter, such as ~~~, or ~!~!~! which would not likely appear within the array.

[Leigh]

True, though multiple characters will not not work in this case. In most versions of CF, multiple characters are treated as separate delimiters. ie ~! means CF sees the values as delimited by ~ OR !. (Things may have changed in CF10). Using a single character like ascii 30, and preserving empty list elements, should get it much closer.

[Henry]

CF10+ user, pls see my other answer.