Is it possible to set an Actions submission criteria that prevents submission if an object has more than a certain number of linked objects?

Question

I currently have an action that creates a new link between an object of type A, named OA, and an object of type B, named OB.

Our workflow has a constraint such that any object of type B can at most, be linked to 4 objects of type A. As such, I would like to define a submission criterion in the action such that submission is blocked if OB is already linked to 4 objects of type A.

I couldn't find a straightforward way to do this using the Action configuration UI. How could I accomplish this?

Answer 1

The easiest way to accomplish this would be to turn your action into a function backed action. This would allow you to take the following steps to accomplish the desired functionality:

1. You can search around to all objects of type A that are linked to OB by writing something like:

// Search around to all objects of type A that are linked to OB
const linkedObjects = OB.objectTypeA.all();
// Now get the number of linked objects
const numLinkedObjects = linkedObjects.length;

2. Prevent the function from running by throwing a UserFacingError if there are more than 4 linked objects

if (numLinkedObjects >= 4) {
    throw new UserFacingError("Objects of type B cannot be linked to more than 4
    objects of type A");
}

For reference, here are some relevant pages in Foundry’s documentation:

• Creating Function Backed Actions (https://www.palantir.com/docs/foundry/action-types/function-actions-getting-started/#getting-started)
• Accessing link types in Functions (https://www.palantir.com/docs/foundry/functions/api-objects-links/#link-types)
• Throwing UserFacingErrors from Functions (https://www.palantir.com/docs/foundry/functions/user-facing-error/)

Answer 2

While you can certainly do this in a Function-backed action, the tradeoff is that you won't get up front validation of the criteria, but rather the user will submit the action and then will received a toast showing the UserFacingError text. So while this technically achieves the validation, it is a sub-par user experience compared to disabling the button with a message or otherwise catching the condition upstream of the action itself in the workflow.

An alternative, iff you're using the action exclusively through Workshop, (this won't work if you want the action to "stand alone" in object explorer), you can create an object set variable that holds the result of the search around and pass that in as a hidden parameter to the Action. You can then set up the Action submission criteria as normal to check the length of that parameter and provide a message back to the user. You can also use that information in the app itself to, for example, conditionally show or hide some other workflow for the condition.

If you take this approach, make sure to add the hubble-oe:hide-action typeclass to one of the object parameters in the Action Form configuration so that the Action doesn't show up where users could use it through Object Explorer.