Shrinking Value List - How?

[HendersonD]

I have a solution that requires what I call a shrinking value list.

I am instituting IP based printing at my school district. All the printers in a particular subnet have the same IP address except the last entry in dotted decimal format. In other words, printers in subnet 80 would all have one of the following IP addresses:

10.121.80.220 through 10.121.80.254

This is a total of 35 different IP addresses. I want these to appear in a drop down menu based on a value list. Lets say the first printer I assign the IP address of 220. When I get to another printer I want the drop down menu of printer IPs to not show 220 since it is already assigned. If 18 IP addresses have already been assigned, the drop down menu built off of the value list only shows 17 choices.

The other way I thought about doing this is just have FileMaker assign the address. I have a checkbox called networked. I have some printers that are not networked (inkjets hooked to local machines) and many that are. When I check the checkbox that says a printer is networked, FileMaker automatically gives it the IP address of 220.

The next printer I come to that I check the networked check box, FileMaker gives it an IP address of 221. FileMaker in essence keeps track of what IP addresses have been assigned. Likewise, if later I uncheck the network checkbox, I want the IP address of this printer to return to the pool of available IP addresses to be reassigned to another printer.

Any suggestions on how to implement this solution, let me know.

Thanks

Dave

[Vaughan]

I recently did something like this. My process works by generating a list of paragraph-delimited values in a global field (or a single-record prefs file). Base the value list on this global field (or single-record prefs file field).

The trick is "subtracting" each IP number from the list as it is used, and "adding" it back when it becomes available again. This isn't too hard, it just requires control over the interface and some nifty string handling scripts. (Hint: the Substitute[] and Set Field[] functions are your friends.)

Alternatively, make a related database where each IP number is a separate record. Then delete (or create) records whenever IP numbers are used (or become available).

[CobaltSky]

Hello Dave,

If you're interested, you'll find a demo of a shrinking value list technique - where values selected in the main file no longer appear on the list, but reappear if they are deleted from the main file - available for download from my web site at the following URL:

http://www.nightwing.com.au/FileMaker/demos/DynamicValues.zip

It's a free unlocked example file, so you'll be able to delve into the works.