This post is a follow-up to a previous post. If you don’t think you need to read it or just don’t feel like it, I’ll just dump the code and a snapshot of how our struct that we’ll be looking at is structured.  However, if you are interested, you can check it out at Creating a Struct by Looping. Anyway, here’s the code and snapshot from the other post.

What our struct looks like.

So what we’re going to do is loop over the ‘loops’ portion of our struct and output each of the 5 loop labels data.  So we are wanting to show the data from our struct like:

OUTPUT OUR LOOPED DATA IN OUR STRUCT

DATA 1: loop_data_1
DATA 2: loop_data_2
DATA 3: loop_data_3
DATA 4: loop_data_4
DATA 5: loop_data_5

The key is that we want to loop over the struct holding this data and output it dynamically.  That way if it is 5 loops or 200 loops the data will always output the same and account the for the varying amounts of data.  Let’s look at the code first.

First we need to get how many sets of data is in our struct.  Remember that the struct that I’m referring to here is the struct inside of the larger struct.  You can get the amount of data in a struct by using the handy ‘structcount()’ method.  Just pass in the struct you want to get the count of. Afterwards, we can loop from 1 to however many sets of data is stored in our struct.  Simple enough so far.

Once inside the loop we need to grab the first set of data in the struct we are looping over.  This is the data with a label of ‘loop1′.  First we set a var that will update with each loop to create the new label.  So loop 1 will be set to ‘loop1′, second loop ‘loop2′, and so on.  Once we have this set we can get our data by using brackets as opposed to just continuing the dot notation.  For example we could get the value of ‘loop1′ by hardcoding the following: VARIABLES.data.loops.loop1.  But that is just going to output the first set of data 5 times.  In order to pass a dynamic value into our struct path that points to our value, we need to use the brackets.  Using brackets, we can pass in our var that sets its value dynamically with each loop, which will output each of the 5 sets of data in our struct.

On a regular basis I find myself needing to create a Coldfusion struct dynamically with a loop.  Although creating a struct in Coldfusion couldn’t be simpler or more intuitive (in my opinion), creating a struct dynamically is a little more problematic.  The problem is that you can’t set the name of your labels in your struct that holds your looped data dynamically.

So for example, let’s say that we want to create a struct that holds five sets of data labeled loop1 that is equal to loop_data_1, loop2 that is equal to loop_data_2, and so on up to loop 5.  When we dump our struct we want it to look like the following.

Dynamically created data in a struct

So let’s look at the code that we need to write to accomplish this.

Everything here is fairly straightforward up until we get to setting the data into the struct inside our loop.  What we need to do is set the label of our data to be “loop” and then whatever the current loop index is.  So if we are on our third loop our label will be “loop3″.  The problem is that you can just set a label by writing VARIABLES.data.loops.loop#VARIABLES.i#.  You’ll get yourself a nice little cf error something along the lines of:

Error thrown when creating a dynamically named struct label.

To get around this all you need to do is wrap your label in quotation marks as is above in the code.  So VARIABLES.data.loops.loop#VARIABLES.i# becomes “VARIABLES.data.loops.loop#VARIABLES.i#”.  And that is it.  Your now able to create and label your struct dynamically.  To see how to output this data dynamically I’ve written another post on Dynamically Displaying Struct Data with a Loop.  Feel free to check it out as well.