loops - Knowing when to insert a comma in ColdFusion -

every often, either in display code or in assembling string, i'll making list , need figure out how insert commas in list.

this how it:

<cfset hide_comma=true> <cfloop ... kind of loop ...>     <cfif hide_comma><cfset hide_comma=false><cfelse>,</cfif>     .... rest of code here ... </cfloop> 

i'm wondering if there's cleaner way of doing this. realize 1 option following:

<cfset output_as_array = []> <cfloop ... kind of loop ...>     <cfset loop_output = "">     ... rest of code here, append output loop output instead ...     <cfset arrayappend(output_as_array, trim(loop_output))> </cfloop> <cfoutput>#arraytolist(output_as_array, ", ")#</cfoutput> 

but doesn't seem clearer.

in django, in contrast, each loop has built in counter can write like:

{% ... kind of loop ... %}     {% if not forloop.first %},{% endif %}     ... rest of code here ... {% endfor %} 

pretty same logic, there's built-in way check loop state, rather having create 1 on own. know when looping through <cfoutput query=...> can use queryname.rowcount purpose, can't find similar in documentation cfloops.

for compiling variable, using valuelist (for queries) , arraytolist functions sensible approach.

if not dealing query or array, build array using arrayappend convert string arraytolist.

(note: listappend ok 1 or 2 items, in long loop it's slower using arrayappend+arraytolist - see info here.)

regarding:

pretty same logic, there's built-in way check loop state, rather having create 1 on own. know when looping through can use queryname.rowcount purpose, can't find similar in documentation cfloops.

short answer: no, there isn't built-in automatic index loops in coldfusion, other standard from/to , query loops.

index loops, can of course use index:

<cfloop index="index" from=1 to=#arraylen(myarray)#>     <cfif index gt 1> not first row </cfif> </cfloop> 

for query loops, use rowcount:

<cfloop query="myquery">     <cfif myquery.rowcount gt 1> not first row </cfif> </cfloop> 

for looping through items, need create own variable:

<cfset row = 0 /> <cfloop index="item" array=#myarray#>     <cfif ++row gt 1> not first row </cfif> </cfloop>  <cfset row= 0 /> <cfloop item="item" collection=#mystruct# >     <cfif ++row gt 1> not first row </cfif> </cfloop> 

in railo, can specify both index , item attributes , have both values available:

<cfloop index="index" item="item" array=#myarray#>     <cfif index gt 1> not first row </cfif> </cfloop> 

the index refers key though, cannot structs (you'll key name, not row number).