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…A long time ago in an app far far away, some folks built a mechanism to handle “variable depth row creation” for parent-child objects. This solution pattern required the Appsheet API at first, and then there were solutions for doing the same without the Rest API. The concept was to have a library of structures to then allow creation of instances of those structures. Several folks were working on this including @tsuji_koichi , @Grant_Stead and others.
Here is the post that required the Rest API:
And here was the post that did the same thing but without the Rest API:
Anyway, since then, I was mulling over any improvements that could be made to this idea of generating instances of variable-depth “things” using actions, but also include support for multiple users and even sequential, ordered tasks, and this is what I came up with:
(The title is misleading, this is not a medical app per se)
Imagine you want a customizable workflow engine, but instead of using our workflows and field values, you want the data itself to be the workflow. New row = new task. But you don’t want a fixed type of workflow process. You want your audience to create NN types of workflows with variable numbers of steps. This is the “variable depth child record problem”. And, to make it even more complex, workflow steps might require predecessor steps, so you need to let your audience specify those as well. You want your workflows to run in series, in sequence.
Some of the design pillars of this app include:
Creating the workflow types
These are parent child relations using tables “Template Library” and “Template Library Steps”: if you study these tables, you’ll see that things are pretty appsheet-normal here. Typical stuff.
We provide a UX view called “Requests”.
Each end user will get only 1 row of data here, so the UX shows a detail view. I have to admit, this part of the solution feels incomplete and janky. But this single row of data has all of the information the operator has selected from the Template Library, plus whatever optional fields a designer wants to add. This data and view is at the very heart of this solution. You select from your template library and then click the red button “Create New Instance” (an action), which triggers the next part:
"Create New Instance" is a grouped action which simply calls two other actions:
** Action “Add New Order from Request” - Copy the template parent to the instance parent (“work orders”) - we have all of our info on our “request” page already, per previous step. We synthesize the Key/UniqueID for “Work Order” at runtime:
any(Work Order Request[TemplateLibraryID]) & "-" & any(Work Order Request[UniqueID])
** Action “Copy Children from Template to Work Order” - Copy the template children to the instance children (“step”). Same basic premise as the previous step, but this one is a bit more complex, and involves a) executing an action of a a set of rows, and then the copy command for the children. Again, we synthesize the Key.
That’s pretty much it. Copy as desired if you would like to study it. We threw in some usual extras like a menu system, users, and such. Hopefully this app can be “pre a porter” for all of your workflow needs.
As always, improvements, errors, ommissions always welcome.
Hi!
In the non-rest-api thread/post I didn’t see an app to copy so it’s hard to see what the exact details are, but at a glance:
- it looks like you were using Device() and uniqueID() whereas I chose to use a “global” table filtered to one row per user. Seems like the same end result. We both chose to ignore a simplistic UniqueID() when initializing the copies.
- In my example children can have predecessors to create sequential steps. In this sense, my app is very “workflow” centric and not as generalized as your solution.
They are quite similar overall and I could not have done what I did without your amazing research! 
“Then while creating a new project the user can simply choose a template to start from”
This part is in the app I linked above, however:
“This allows you to “convert” any project into a template”
I didn’t think to build something in the opposite direction! E.g. if I build a one-time workflow process I’d like it to also be a template. That’s a cool idea.
But I guess in my app link above, the “templates that have tasks” (from the main menu) is the place where you would design something ad hoc. Maybe I could add a “status” flag like DRAFT | PRODUCTION so that end users can only select production workflows, or something like that.
I didn’t want to go nuts over-building this though, so that the copy-and-customize would not be overly complex for the receiver of the app
OK another follow up. This stuff will nag and nag and nag my brain until I figure it out…
re: the concept of load balancing tasks among a group of users who have the skillset to perform the task
I was able to get this working in the above app. (If you already copied it, you’ll need to copy it again). It’s some crazy gnarly expression work to get a list of “people who have the least number of open tasks, which tasks have a given skillset assigned to them”.
- People can have more than one skill, but
- a task in the task library can have one and only one skill
Anyhoo, here’s a short video showing the end result:
And you will see the gnarly calcs in table “Template Library Steps”. These calcs are referenced in Action “copy template child to work order step”
I was not able to place these calcs in the action itself. I wanted to for performance reasons. But the platform was ignoring the email assignments. I think this is due to the way we perform client-side vs. server-side expressions. I mention this in case - at scale - these calcs start to perform slowly.
And now, it’s advil time…
btw @Grant_Stead your idea of “dropping a user into a quick edit table” on a grid to further edit the assignments was great, I’ve added that to the example. E.g. after an instance is created:
Yes I know… I’m just not sure which screen shoots to post 
I’ve been working on it all day trying to get the action back… I know that I’ll learn more if I can sort it myself but I’m running out of options. 
I don’t mind spending the time going through every setting & checking them against your sample app. However even when I copy your sample app again (from the link above) to use as a reference, the action is not showing for me in that either. 
Got it… I’ve got the Action button to show again. 
I think that it was something to do with my ‘Request_Detail’ & ‘Request_Form’ views being mixed up.
This is a great app… I’m definitely going to be using this a lot. I really like the ‘Predecessor’ options, making it very versatile.
Thanks for the help,
Darren
