A more generic "splitListItem"

ccorcos · June 3, 2021, 11:39pm

The current implementation checks to see if the grantParent is a specific itemType:

ProseMirror/prosemirror-schema-list/blob/400e0b395896ebb123db6d119a113a846321afce/src/schema-list.js#L117

    
      
                splitPos += 2 * splitDepth
              }
              splitPos += parent.child(i).nodeSize
            }
            return tr
          }
          
          
// :: (NodeType) → (state: EditorState, dispatch: ?(tr: Transaction)) → bool
          // Build a command that splits a non-empty textblock at the top level
          // of a list item by also splitting that list item.
          export function splitListItem(itemType) {
            return function(state, dispatch) {
              let {$from, $to, node} = state.selection
              if ((node && node.isBlock) || $from.depth < 2 || !$from.sameParent($to)) return false
              let grandParent = $from.node(-1)
              if (grandParent.type != itemType) return false
              if ($from.parent.content.size == 0 && $from.node(-1).childCount == $from.indexAfter(-1)) {
                // In an empty block. If this is a nested list, the wrapping
                // list item should be split. Otherwise, bail out and let next
                // command handle lifting.
                if ($from.depth == 2 || $from.node(-3).type != itemType ||

I’ve added a new “checkbox” list type and I found it a little awkward having to create a separate command for splitting checkbox lists (or any other kind of list, also indentation commands, etc.). Foreseeing that others may have run into this, I thought I’d explain my solution:

I fiddled with the code a little bit:

I added list to the node-spec.

declare module "prosemirror-model" {
	interface NodeSpec {
		list?: boolean | null
	}
}

I simply check that the greatGrandParent is a list and derive the itemType from the grandParent.

		let greatGrandParent = $from.node(-2)
		if (!greatGrandParent.type.spec.list) return false

		let grandParent = $from.node(-1)
		let itemType = grandParent.type
		// if (listItem.type != itemType) return false

I’m curious what you think of this approach @marijn. I think it might make sense for the list concept to be a bit generalized.

marijn · June 7, 2021, 2:02pm

Since binding a separate command isn’t all that hard, and most list types can share item types, I don’t think this is a big enough issue to warrant adding another field to node specs for.

bhl · June 7, 2021, 9:46pm

Yeah, a good workaround would be to make your own custom nodespecs with list defined, and then re-write some custom commands to take advantage of that.

A notable example of something similar is in prosemirror-tables, which defines a tableRole as part of its table nodespecs, and then uses that internally in commands and utils.