Unplanned
Last Updated: 23 Jul 2021 11:43 by ADMIN
Ludvik
Created on: 12 Jul 2021 09:28
Category: Grid
Type: Bug Report
0
Server Grouping with virtual scrolling is duplicating records - when I select a group with records inside, the scrolling in the group down requests another page with page=1
The easiest steps to reproduce this behaviour is

1. Go to demo page 

https://demos.telerik.com/kendo-ui/grid/server-grouppaging-virtualization and click to Edit in Dojo. It o

Then, to get rid of narrow groups I will change grouping from 

pens https://dojo.telerik.com/afoCefOJ

 

group: [{
                        field: "city",
                        dir: "asc"
                    }, {
                        field: "companyName",
                        dir: "asc"
                    }],

 

group: [{
                        field: "city",
                        dir: "asc"
                    }],

and also adjust pageSize to 10:

pageSize: 10,
2. Now, when I Run example, open Chrome Debug tools to Network traffic and expand Shady shores, I get records starting with:

GC30TRSSMTI706Z, Ireland

I can see first request starting wtih Page:1

3. Now I scroll the virtual view just a bit down to get another 10 records. Surprisingly, I get same records again.

GC30TRSSMTI706Z, Ireland

We need to resolve this bug, because we can not use grid without this features (virtual scrolling and grouping).

Thank You.

Ludvík Mikulenka 


12 comments
ADMIN
Angel Petrov
Posted on: 23 Jul 2021 11:43

Hi Ludvik,

I am sorry to say but I can not provide a certain timeframe in whcih a fix for this issue will be included. We will do our best to resolve the matter as soon as possible.

Regards,
Angel Petrov
Progress Telerik

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Ludvik
Posted on: 22 Jul 2021 13:25

Hi Angel,

do You have an estimation when this issue can be solved?

Thanks.

Ludvík

ADMIN
Angel Petrov
Posted on: 21 Jul 2021 11:59

Hi Ludvik,

We did a thorough research and it seems that there is a bug that we should reference when there is one level of grouping. We have already logged it and you can monitor our progress from here.

As a token of gratitude for reporting this to us I have updated your account points. Additionally I want to apologize for any inconvenience this issue may have caused you.

Regards,
Angel Petrov
Progress Telerik

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Ludvik
Posted on: 20 Jul 2021 14:19

Hi Nikolay,

what do You mean by "setting a bigger page size"? Can please tell me what exact size should we set to get proper requests? As I mentioned in my reply from 13th July, I tried to set page size to 300 records but we got still the same results.

Can You please provide working dojo example?

Thank You.

Ludvík

ADMIN
Nikolay
Posted on: 20 Jul 2021 13:40

Hi Ludvik,

Please accept my apologies for the late response.

I spoke with the Dev team and this is a corner case with the Virtual scroll. We have been contacted before about this and what we recommend is setting a bigger page size when this will be avoided.

Let me know you need further assistance.

Regards,
Nikolay
Progress Telerik

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Ludvik
Posted on: 20 Jul 2021 08:25

Hi Nikolay,

any progress on this issue?

Thanks,

Ludvík

ADMIN
Nikolay
Posted on: 15 Jul 2021 07:36

Hi Ludvik,

Just to let you know I am still working on the case. Please expect a follow-up shortly.

Regards,
Nikolay
Progress Telerik

Virtual Classroom, the free self-paced technical training that gets you up to speed with Telerik and Kendo UI products quickly just got a fresh new look + new and improved content including a brand new Blazor course! Check it out at https://learn.telerik.com/.

Ludvik
Posted on: 14 Jul 2021 08:28

Dear Nikolay,

please use this dojo example Untitled | Kendo UI Dojo (telerik.com), where You can see the problem (page size is set to 30 records):

  • if You open group Argentina data are fetched normally - first line
BBT1KJMN05CNG4UArgentinaTortuga Restaurante Seven Mile Tesuque PuebloThree WayO4
  • When You scroll down after 30 records data are fetched again and in the request is again page=1 and You can see that record on position 31 is again
BBT1KJMN05CNG4UArgentinaTortuga Restaurante Seven Mile Tesuque PuebloThree WayO4

 

Thanks.

 

Ludvík

ADMIN
Nikolay
Posted on: 14 Jul 2021 08:01

Hi Ludvik,

Thank you for updating me on the case.

Unfortunately, I am not able to reproduce this behavior with a page size three times larger than the number of visible table rows in the data area. Is it possible to share a Dojo demo or a runnable page where this is isolated and demonstrated? This will allow me to investigate further.

Looking forward to your reply.

Regards,
Nikolay
Progress Telerik

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Ludvik
Posted on: 13 Jul 2021 11:25
Sorry, I forgot the attachments.
Ludvik
Posted on: 13 Jul 2021 11:24

Hi Nicolay,

unfortunately grid page size does not help in our case. I tested page size from 100 up to 300 records but we still have the same issue:

  • when I group grid by column everything is correct (picture 1)
  • then I open the group and data with first page are loaded correctly (see red rectangle on the bottom with page number=1 and size=300 - picture 2)
  • when I scroll down after 300 records grid is not fetching page 2 BUT page 1 again and that is the issue we need to resolve (picture 3) - again check red rectangle on the bottom -> there is page number=1 and size=300 again
  • then when I scroll down again grid is fetching page 2 etc.

So long story short the problem is grid is fetching first page twice (when 1 open the group and when I scroll and grid is fetching the date for the second time).

Can You please help us to avoid this problem?

Thank You.

Ludvík

ADMIN
Nikolay
Posted on: 13 Jul 2021 08:40

Hello Ludvik,

Thank you for sharing the Dojo demo with me.

When enabling Virtual scrolling to the Grid it is important to provide a page size that is large enough, so that the table rows do not fit in the scrollable data area. Otherwise, the vertical virtual scrollbar will not be created. The page size of the Grid must be over three times larger than the number of visible table rows in the data area. 

This is pointed out in the following Known Limitations documentation article:

Setting a Grid page size of 30 solves the issue.

Regards,


Nikolay
Progress Telerik

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