Ben Nadel
On User Experience (UX) Design, JavaScript, ColdFusion, Node.js, Life, and Love.
I am the chief technical officer at InVision App, Inc - a prototyping and collaboration platform for designers, built by designers. I also rock out in JavaScript and ColdFusion 24x7.
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Ben Nadel at CFUNITED 2009 (Lansdowne, VA) with:

Looping Over Times In ColdFusion

By Ben Nadel on
Tags: ColdFusion

Looping over times in ColdFusion is the same exact thing as looping over dates in ColdFusion, but sometimes, people don't quite make the mental leap on their own. And so, I thought I would just quickly demonstrate that this was possible.

The key to looping over times is to understand that a time value is really just a fractional date value and that when looping over it, your loop increment (step value) should also be a fractional time value as well. In this case, we are going to loop from 8:00 AM to 5:00 PM using a one hour increment:

  • <!---
  • When looping over the hours in the day, we are going to
  • use an index loop and for each iteration, we are going
  • to increase the index by a single hour (the numeric
  • timespan representing an hour fraction of the day).
  • --->
  • <cfset dtHour = CreateTimeSpan(
  • 0, <!--- Days. --->
  • 1, <!--- Hours. --->
  • 0, <!--- Minutes. --->
  • 0 <!--- Seconds. --->
  • ) />
  •  
  •  
  • <!---
  • When looping over the hours in the day, we can enter the
  • start and end time as "readable" time. ColdFusion will
  • automatically convert those time strings to their numeric
  • equivalents for use within the index loop.
  • --->
  • <cfloop
  • index="dtTime"
  • from="8:00 AM"
  • to="5:00 PM"
  • step="#dtHour#">
  •  
  • #TimeFormat( dtTime, "hh:mm TT" )#<br />
  •  
  • </cfloop>

Running the above gives us:

08:00 AM
09:00 AM
10:00 AM
11:00 AM
12:00 PM
01:00 PM
02:00 PM
03:00 PM
04:00 PM
05:00 PM

Notice that in order to get our CFLoop step value, we are building a time span object (returns a Double value) that is created using just a single hour. The mental leap to make here is that that time span value could be anything you want. It could be days, hours, minutes, or seconds.

Just remember, dates are numeric values. Because an indexed CFLoop is iterating over numeric values, ColdFusion accomplishes this by converting your date/time value for the from/to attributes to numeric values behind your back. Embrace this, do not fear it :)

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Reader Comments

@Trent,

I just ran this:

<cfset dtHour = CreateTimeSpan( 0, 1, 0, 0 ) />

<cfloop
index="EdtTime"
from="8:00 AM"
to="8:00 PM"
step="#dtHour#">

#TimeFormat( EdtTime, "hh:mm TT" )#<br />

</cfloop>

... and it worked just fine. You have to use the TimeFormat(). Are you? If you don't, it just comes out as fractions.

Hey guys, thanks for the examples. I'm having issues displaying times from 8pm to 4am (see code below). If you copy+paste that, nothing displays. Any help is appreciated.

<cfset dtHour = CreateTimeSpan( 0, 1, 0, 0 ) />

<cfloop
index="EdtTime"
from="8:00 PM"
to="4:00 AM"
step="#dtHour#">

#TimeFormat( EdtTime, "hh:mm TT" )#<br />

</cfloop>

@Alan,

You can't do that because there is no "date" involved. As such, it sees those times as already having passed each other (4AM is less than 8PM of the *same* day).

I suspect that in order to get that to work, you would need to add an actual date to the time:

  • <cfloop
  • index="edtTime"
  • from="#createDateTime( 2011, 1, 1, 20, 0, 0 )#"
  • to="#createDateTime( 2011, 1, 2, 4, 0, 0 )#"
  • step="#dtHour#">
  •  
  • ... your code ...
  •  
  • </cfloop>

This way, you're not just using hours, you actually going from the hours in ONE day to the hours in the NEXT day.

See if that works. The date part is really irrelevant as long as the day in the TO is one more than the day in the FROM.

@Alan,

Glad you got it worked out; but, how did military time solve the problem? Wouldn't 20:00 till be greater than 04:00? It seems you'd still have a loop that wouldn't start?

Yes, but you got me thinking about how to "add time" to days, so to speak. Here is what I ended up doing:

  • <cfset theDate = #form.startDate#>
  • <cfset theHour = #form.hour#>
  •  
  • <cfset dtHour = CreateTimeSpan( 0, 1, 0, 0 ) />
  •  
  • <cfset shiftLength=8>
  • <cfset shiftDateTime=theDate & " " & theHour>
  • <cfset startTime=ParseDateTime(shiftDateTime)>
  • <cfset endTime=DateAdd('h',shiftLength,startTime)>
  •  
  • <select name="earlyOutHour">
  •  
  • <cfloop index="edtTime" from="#StartTime#" to="#EndTime#" step="#dtHour#">
  • <option value="#TimeFormat(EdtTime, "hh:mm TT" )#">#TimeFormat(EdtTime, "hh:mm TT" )#</option>
  • </cfloop>
  •  
  • </select>