5 Replies Latest reply on Mar 24, 2012 5:19 AM by BKBK

    Checking for duplicates in a listappend


      At certain points I add values into a variable using listappend, might be a single digit, might be a valuelist of numbers from a cfquery result.


      The question I have is, does anybody know of a simple way to make sure that duplicates are not added to the list?


      Apart from looping over the results of the cfquery and then checking each one to see if it is in the list and if not then adding it.


      I'm wondering if CF8 has anything built in that I have overlooked?





        • 1. Re: Checking for duplicates in a listappend
          Dan Bracuk Level 5

          cflib.org has a function called ListDistinct.  Get it.  Then build your list without worrying about duplicates and use this function when you are done.

          • 2. Re: Checking for duplicates in a listappend
            ACS LLC Level 1

            Thanks Dan. I didn't find it on the site you mentioned, but a Google search did take me to:




            Not sure if it's up to date, it was dated 2002. I took a look at the CFM that came with it,heres the code inside it, pretty much how I would have written it manually in CF, I think that it would possibly just use too many resources to keep looking over the list. Here's the code


            <CFPARAM name="Attributes.list" default="">

            <CFPARAM name="Attributes.return_vname" default="distinct_list">

            <CFPARAM name="Attributes.sort" default="No">


            <CFSET temp_list="">

            <CFLOOP list="#Attributes.list#" index="i">

                <CFIF ListFindNoCase(temp_list,i) EQ 0>

                    <CFSET temp_list = ListAppend(temp_list,i)>



            <CFIF Attributes.sort EQ "Yes">

                <CFSET "Caller.#Attributes.return_vname#" = ListSort(temp_list, "Text")>


                <CFSET "Caller.#Attributes.return_vname#" = temp_list>


            • 3. Re: Checking for duplicates in a listappend
              Dan Bracuk Level 5

              If you want to use it as it is, you'll also need teh ListSort function.  It's in the same library.

              • 4. Re: Checking for duplicates in a listappend
                ACS LLC Level 1

                Ah, I didn't notice that. So regardless of how I use it I presume I'll need that?


                the instructions just had it set up as a custom tag

                • 5. Re: Checking for duplicates in a listappend
                  BKBK Adobe Community Professional & MVP

                  ACS LLC, you could translate the custom tag into a function, something like this


                  <cffunction name="removeDuplicates" access="public" output="no" returntype="string" hint="This function will take a list and remove all duplicate values from it.">




                  list (required): input list

                  sort (optional): perform a text-sort on the list?  Yes or No. Default is No.



                  <cfargument name="list" required="true" >

                  <cfargument name="sort" required="false" default="no">


                  <cfset var returnList = "">

                  <cfset var temp_list    = "">


                  <cfloop list="#arguments.list#" index="i">

                      <cfif listfindnocase(temp_list,i) eq 0>

                          <cfset temp_list = listappend(temp_list,i)>




                  <cfif arguments.sort eq "yes">

                      <cfset returnList = listsort(temp_list, "text")>


                      <cfset returnList = temp_list>



                  <cfreturn returnList>



                  <cfset testlist="a,a,1,1,2">