add short-circuit to handlers (removing, unpublishing etc.)

[lampersky]

There are many cases where you could need prevent some DefaultContentManager actions. Using some custom logic. Currently, we can only control the execution of code in a binary way via Permission.

Use case 1: Let's say you have some items selected in many ContentPickerFields, and you would like to prevent user to remove those ContentItems with some user friendly message, like: "you can't remove this ContentItem becasue it is used in at least one ContentPickerField".

Use case 2: Suppose we want to check if a similar ContentItem already exists before creating new one. To avoid duplicates.

I think it would be good to have an option to cancel any of those operations from within those handlers: DraftSavingAsync, PublishingAsync, UnpublishingAsync, CreatingAsync, UpdatingAsync, RestoringAsync, RemovingAsync, CloningAsync.

I'm thinking about something like this (pseudo code):

(change in DefaultContentManger)

(change in AdminController)

(example use)

(example of short-circuit on RemovingAsync)

Of course, there are much more places to change, but I just wanted to better explain my idea.

/cc: @jtkech I am curious about your opinion.

[sebastienros]

It's like the behavior for UpdateAsync where we manage errors with the ModelState: https://github.com/OrchardCMS/OrchardCore/blob/5a472d483fc360d1e1aa69dc7e098be6a038e62c/src/OrchardCore.Modules/OrchardCore.ContentFields/Drivers/TextFieldDisplayDriver.cs#L56C101-L56C101

So maybe not return a result type, but use a custom context object to add errors on it. The error messages should not come from the controller (like it's done in your examples).

To make it a non-breaking change it could be on new overloads.