“An essential part of being a humble programmer is realizing that whenever there’s a problem with the code you’ve written, it’s always your fault.”
— Jeff Atwood
Now that you can get yourself a copy of the new Quebec version of ServiceNow, you can start playing around with all of the new features that will be coming out with this release. One of those new features is Flow Variables, which look like they might serve to replace the Scratchpad that I had built earlier for pretty much the exact same purpose. Since I have used that custom feature in a variety of different places after I first put it together, the trick will be to see if I can just do a one-for-one swap without having to re-engineer things using an entirely different philosophy.
I like building parts, but I also like to get rid my home-made parts whenever I find that there is a ServiceNow component that can serve the same purpose. If I can figure out how to make a Flow Variable do all of the things that I have been able to do with a Scratchpad Variable, then I will be the first in line to throw my home-made scratchpad into the dust bin. But before we get too far ahead of ourselves, let’s try a few things and see what we can actually do.
According to the ServiceNow Developer Blog, you can set the value of a Flow Variable inside of a loop and use it to control the number of times that you go through the loop.
Let’s create a sample flow, define our first Integer Flow Variable and then set up a loop that we can escape based on the value of the variable. Open up the Flow Designer, click on the New button, select Flow from the drop-down, and then name the new Flow Sample Flow. From the vertical ellipses menu in the upper right-hand corner, we can select Flow Variables and define a new variable called index of type Integer. For our first step, we can set the value of our new variable to 0, and then we can add a loop that will run until the variable value is greater than 5. After that, all we will have to add is another step inside the loop to increment our index variable.
All of that went relatively smoothly for me until I tried to add the +1 to the Set Flow Variables step inside of the loop. Once I dragged the index pill into the value box, it would not accept any more input. I tried putting the +1 in first, and then dragging the pill in front of it second, but that just replaced the +1. I could never get the pill+1 value like the sample image in the developers blog entry. Obviously, I was doing something wrong, but I did not know exactly what. Nothing that I tried seemed to work, though, so eventually I decided to give that up and just script it.
It was a fairly simple script that just added one to the existing value.
return fd_data.flow_var.index + 1;
Unfortunately, that resulted in a text concatenation rather than an increment of the value. 0 + 1 became 01 and 01 + 1 became 011 and so forth. Even though I had defined my variable as an Integer, it was getting treated as if it were text. No problem, though … I will just convert it to an Integer before I attempt to increment the value.
return parseInt(fd_data.flow_var.index) + 1;
That’s better. Now 0 + 1 becomes 1 and 1 + 1 becomes 2 just the way that I thought that it should. But … things are still not working the way that they should. In my test runs, the new value was not always present when I reentered the loop. 0 + 1 became 1, but then the next time through, the variable value was still 0. That’s not right! I kept erroring out by looping through the code more than the maximum 10,000 times until I finally changed my bail-out condition to be any value greater than zero. Even then, it ended up looping 456 times before it dropped out.
Clearly, something is not quite right here. It is possible that I just got a hold of an early release that still has a few kinks left to be worked out, but if you’re a true believer in The First Rule of Programming, then you know that I’ve just done something wrong somewhere along the line and need to figure out what that is. Obviously, you shouldn’t have to run through the loop over 400 times just bump the count above zero.
Well, back to the drawing board, as they say. Maybe I will have to resort to reading the instructions. Nah … I’ll just keep trying stuff until I get something to work. In the meantime, it looks like I won’t be flushing the old home-grown scratchpad down the drain just yet. At least not until I figure out how to make this thing work. Too bad, though. I had such high hopes when I saw that this was coming out.
Note: Eventually, I was able to figure out what I was doing wrong.
