Tables need "remove empty row" post-fixer

[scofalik]

There is at least one case when it is possible to create an empty table row, even without real-time collaboration. I suspect it is also possible through some simultaneous changes in RTC.

To reproduce it, you need a table where there is only one non-spanned cell in a row and then remove this row through removing a column. See the gif below for an example.

A similar thing happens when merging down but it is actually handled in the command:

// Remove empty row after merging.
if ( !removedTableCellRow.childCount ) {
	removeEmptyRow( removedTableCellRow, writer );
}

However, things like this should be handled through post-fixers. A command should do what it is supposed to do and then post-fixer should clean whatever incorrect state happens. It is better to handle it in post-fixer because:

1. Multiple commands are handled at once.
2. RTC scenarios are handled as well.

[scofalik]

Additonally, "remove unnecessary colspans/rowspans" post-fixer will be needed.

[jodator]

Hmm... I think that this might be handled by the merge cell command or other. Probably the delete row command wasn't tested. Anyway - yes we need this.

[scofalik]

I am not sure if I read your post correctly but I just wrote why it cannot be handled through commands.

[mlewand]

Issue in remove column described in the first post here caused #6422. I wonder whether we should really go for a post-fixer, or make sure that the commands properly handle the model. Another solution might be both.

[Reinmar]

I wonder whether we should really go for a post-fixer, or make sure that the commands properly handle the model. Another solution might be both.

I'd go with commands leaving a clean editor first and see if we have any problems. If we'll see that we cannot really control it from the command perspective, we need a post-fixer indeed. A post-fixer should be a last resort.

[jodator]

So ultimately we went with the cleanup after yourself in commands and utils by introducing TableUtils.removeRow() and TableUtils.removeColumn() methods.

This is required to use that always as table modifications are not trivial and simple remove row element is not enough to create a proper table state. The reason of this is that after merging some cells you might create an empty row - which will yield table model error as defined in HTML specs. The solution for this is to remove this row and update overlapping cells rowspan attribute to not create an invalid table state.

Handled, among others, by: #6502.