sap.ui.table.Table: When scrolling, variable row heights don't allow all rows to be seen

[cmastrandrea]

OpenUI5 version: latest

Browser/version (+device/version): All common browsers, latest versions

Any other tested browsers/devices(OK/FAIL):

URL (minimal example if possible): http://jsbin.com/zuzeye/6/edit?html,output

User/password (if required and possible - do not post any confidential information here):

Steps to reproduce the problem:
1.Use scrollbar to scroll all the way down through the list.
2.Note that the last 3 or so rows cannot be scrolled into view.
3.Clicking in the list and using the arrow keys does let you scroll the remaining rows, but the last one still has some issue and is quickly scrolled off again.

What is the expected result? Expected that the all rows could be made visible by dragging down the scrollbar.

What happens instead? The scrollbar doesn't allow the last rows to be displayed, possibly because of the variable row heights.

Any other information? (attach screenshot if possible)

[Michadelic]

Hello cmastandrea,

i also verified this one and created an internal ticket: 1580010731
We will take a look and get back to you.

Kind Regards,

Michael

[SebastianRied]

Hi cmastandrea,

unfortunately we can't provide a fix here due to how the table is designed to work, let me try to give some details:
The tables of the sap.ui.table library aim for huge amount of data (i.e. lots of rows). Since it would break the performance to have own controls for each row, the table simply reuses the controls of the rows. It's just the context which is changed by scrolling. Since there is no real scroll area, the table can just only take the length of the binding, the number of visible rows of the table and the current height of the table (influenced by the controls of the row template and their current content) and calculate a scrollbar length which gets applied. This happens in a delayedCall of 250ms - therefore it can happen in unlucky circumstances that the scrollbar length is not set correctly. However, when the row height remains stable, this delayedCall gives a real performance boost. Maybe you've noticed that the table never clips a row, it always shows the complete control - this exactly due to the concept of reusing controls.

I understand that you dislike the current behavior of changing table height, scrollbar length and sometimes not reaching the last row of the table (caused by different row heights). Hence I'd propose to use the sap.m.Table for variable row heights. The sap.m.Table could be placed inside a scroll container with a fixed height. However, the sap.m.Table is not meant for mass-data since it would render the complete data as a table. You can reduce the margins of the controls inside the sap.m.Table by setting the style class sapUiSizeCompact to make the m.Table better fit on desktops.

Best regards
Sebastian

[thilo-dev]

Hi cmastandrea,
As this issue has been idle for some time and seems to be fixed I close it for now.
Please feel free to reopen if you want to follow-up.
Thanks, Thilo

[cmastrandrea]

Thilo - Has this issue been fixed in a not-yet-released version of OpenUI? The sample app I provided still behaves incorrectly and it's using the latest release from https://openui5.hana.ondemand.com/resources.

It sounded like from Sebastian comments that this would not be fixed at all. I think that's very unfortunate because there is no table alternative for showing large amounts of data, so all users would have to accept this behavior. This is essentially a data integrity issue since some rows are excluded from the display, leading them to reach inaccurate conclusions about the data they are viewing.

It seems to me that a fix for this problem is achievable without having to redesign the way the table works or affect its current performance. At a minimum, overestimating the extent of the scrollbar when variable row heights are in play is much better than underestimating and not showing all rows.

[krisho007]

This is three years later and I still have the issue with the scrollbar not scrolling to the last row (whenever there are wrappings). Using 1.52.16. I am using a SmartTable though. (using sap.ui.table.Table)

[sfdfklskldf]

Also true with SAPUI5 Version 1.60.1 is there any chance this will be fixed? Otherwise this table should be marked as obsolete. This is not usable. Or is there any solution to adapt the scrollbar to the table somehow?

[boghyon]

@sfdfklskldf

Or is there any solution to adapt the scrollbar to the table somehow?

See the footnote in https://ui5.sap.com/#/topic/148892ff9aea4a18b912829791e38f3e.html for supported controls and the required settings.