Select only one choice in grid selection

I find the official appian SAIL recipe approach of throwing a validation error to be unnecessary and kinda clunky, no offense, and to be quite honest it doesn't make much sense to me that after all this time they've never engineered the paging grid component to contain a "singleSelect" parameter (or alternatively "maxSelections" for greater flexibility) where the "select all" control will be hidden when # of selections is restricted (or at least, smaller than the current page size).

Out of necessity I've developed the following code which handles the single-select use case pretty strongly IMHO, and it has been refined quite a bit over the past 3 years or so:

saveInto: {
  a!save(
    local!gridSelection,
    a!gridSelection(
      pagingInfo: save!value.pagingInfo,
      selected: index(
        save!value.selected,
        length(save!value.selected),
        {}
      )
    )
  )
}

This code does similar to what some of the prior examples here suggest, though a bit more compact, and automatically handles the use case of de-selecting the current selected item.  Note that there's currently no way to avoid the behavior where clicking the "select all" control causes the last item on the current page to be selected, as mentioned above - this is probably the single strongest reason there really needs to be an OOB control for restricting the number of selections.

Hey Mike,

Agree that there should be an out of the box option to handle it in an elegant manner.

Also, When you say ,"Note that there's currently no way to avoid the behavior where clicking the "select all" control causes the last item on the current page to be selected, as mentioned above". Did you try the code I gave above.

because it works for me, i.e retains the previous selected value.
For this reason only I wont directly index the length but use it to see if I have to index the first or the last one

see the lines -

if(
  --If below is true it means you have clicked select all
  length(
    local!gridSelection.selected
  ) > 2,
  --logic to retain the older value
  index(
    local!gridSelection.selected,
    1,
    ""
  ),
  --Logic to retain the new value
  index(
    reverse(
      local!gridSelection.selected
    ),
    1,
    ""
  )
)

please let me know if this helps

I Agree that there should be an out of the box option to handle it, but we should also accept this fact, Appian currently releasing pretty huge and great updates into each one of their releases. And for 17.2 they have majorly focused on Better UI designing, Decision and easy integration approach. They might have this also in their mind, and in future they may release an out of the box for this as well. For example they have automate File Upload component for multiple in a decent way in 17.2 release, in the same way they may release these features also in upcoming releases, but can't be sure.

But i feel, if they provide everything OOTB then there won't be any challenges, difficulties and won't be anything to learn for the developer, and the designer won't have understanding about what's going on behind the screen, and however we can handle these scenarios by writing our own logic also.

manisht209 - "it works for me, i.e retains the previous selected value."

You're right - I suppose what I should really say instead is "there's no way to disable the select all control, as it will not give the user their desired results" - but I never thought to try retaining the original selection.  I will try incorporating something similar into my current code.

The following should take that into account, plus if the user clicks "select all" when nothing is selected yet, the selection will remain empty in this version.

(Note that this code, as well as your code, both have a quirk when "select all" is clicked on a page containing 2 items - I can't find an easy way around this but it's probably not a big deal)

saveInto: {
  a!save(
    local!gridSelection,
    a!gridSelection(
      pagingInfo: save!value.pagingInfo,
      selected: if(
        length(save!value.selected) > 2, /* override if "select all" was clicked: retain original value */
        local!gridSelection.selected,
        index(
          save!value.selected,
          length(save!value.selected), /* for normal clicks, this will correctly capture the first or any subsequent click, as well as a de-select click */
          {}
        )
      )
    )
  )
}

manisht209 - "it works for me, i.e retains the previous selected value."

You're right - I suppose what I should really say instead is "there's no way to disable the select all control, as it will not give the user their desired results" - but I never thought to try retaining the original selection.  I will try incorporating something similar into my current code.

The following should take that into account, plus if the user clicks "select all" when nothing is selected yet, the selection will remain empty in this version.

(Note that this code, as well as your code, both have a quirk when "select all" is clicked on a page containing 2 items - I can't find an easy way around this but it's probably not a big deal)

saveInto: {
  a!save(
    local!gridSelection,
    a!gridSelection(
      pagingInfo: save!value.pagingInfo,
      selected: if(
        length(save!value.selected) > 2, /* override if "select all" was clicked: retain original value */
        local!gridSelection.selected,
        index(
          save!value.selected,
          length(save!value.selected), /* for normal clicks, this will correctly capture the first or any subsequent click, as well as a de-select click */
          {}
        )
      )
    )
  )
}