Is it possible to display (or link to) the related document on a task form?

But.. You have it like OOTB  It is called "Related Items" field:

It shows a link to the item on which the workflow is run.

If you'd like to show more metadata of the related item you can use Nintex Forms - the default Nintex Form does present metadata of the related item below the task data.

And last, but not least, you can use custom JavaScript for the existing view/ edit forms on Task List, but it's a bit more complicated

Regards,

Tomasz

Tomasz,

Thanks for the reply...I went looking for a "Related Items" control in the form designer and can't find one. I'm using the "Edit Task Form" option in the workflow Assign a Task action.

Am I looking in the right place?

Thanks,

Steve

But in that case if you start creation of the form, you should have already visible fields from the tasks list as well as those from related item:

1. Click "Edit Task Form":
   
2. You'll find related item metadata column below task:
   

The same for "Assign a task".

Regards,

Tomasz

So, in order to test, here's what I did:

1. Create a new task list, ensure that "Related Items" column is in the list. Check!

2. Enter a new task and add a related item to it and see where it is on the form order. Check!

3. Create a Nintex form, don't change ANYTHING, publish it. Check!

4. Then, where the "Related Items" was, I have nothing!

Whereas before, I had

I even tried putting a Calculated Field and using lookup("listName", "ProjectName", ProjectName, "Related Items") and got nada. But the related item is still there, as I can see in my list view:

So, sorry to say I haven't figured out your problem, but I've recreated it and done some preliminary digging!

to have related items on Nintex Form you have to trigger it's creation from the task action, as I presented.

Also publish your workflow before, if it is created from scratch and is using a blank tasks list, do that Nintex will adapt the chosen task list and provision there it's content type and some additional fields.

Regards,

Tomasz

Hey ‌, what if a user wasn't generating the task from a Workflow? As in, they create an ootb SharePoint task list and are allowing users to generate the tasks manually from there?

Well.. Then you have to manually add fields and make them lookups to a particular list/ library querying data where list/ library item ID is equal to related item.. Honestly - I have no idea. Moreover - in OOTB task you can put more than one item as a related. When creating a task for the approval it is always a 1-1 relation.

Regards,

Tomasz

Yeah, even trying with lookups I wasn't getting anywhere, but I'm sure it's possible. Just maybe not by me!