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Lazy loading tree, multiple columngrouping [message #1391765] Tue, 01 July 2014 07:35 Go to next message
Daniel Sievers is currently offline Daniel Sievers
Messages: 2
Registered: July 2014
Junior Member
Hello experts,

I am a german software developer. I am very interested in NatTable and try to use it for our Application. We need a high-performance Table/Grid with the standard functions like sorting, filtering, Tree, etc... to show large Datasets.

Currently, we have problems with the following functions:

  • TreeGrid with lazy dataloading
  • multiple ColumnGroups (more than 3 Level)

Functions like sorting and filtering are implemented.

Now i have two questions:

I've read in the current roadmap, that the function 'column grouping' would be refactore. After the refactoring, it is possible to group more then 3 levels?
Currenty you can create a ColumnGroupGroupHeaderLayer that contains a ColumnGroupHeaderLayer.

Is there a way to load the children of a tree only once when their parent is expand? (like the ITreeContentProvider from JFace?) If i understand the structure aright, then the TreeList (respectively the underlying lists) have to contains all Elements (or at least the details elements) and create from the detailsElements the structure. (Bottom to Top) In my case i have the root elements and can retrieve their children. (like a FileBrowserTree, Top to Bottom)

Currently i try to avoid this problem by catching the ExpandEvent and load the data and put it into the list. I hope this will work. If i have solve this problem successully ich will post it.


I use the current release (Version 1.1.0)
I'm deeply grateful if anyone can respond to my questions.
Re: Lazy loading tree, multiple columngrouping [message #1391839 is a reply to message #1391765] Tue, 01 July 2014 09:39 Go to previous messageGo to next message
Dirk Fauth is currently offline Dirk Fauth
Messages: 1227
Registered: July 2012
Senior Member
Hi,

yes the refactoring would include multiple grouping levels. That's why a refactoring is necessary, so it is not necessary to create a new layer for a grouping, but reuse the ColumnGroupHeaderLayer.

The default tree functionality in NatTable, that is implemented using GlazedLists, is transforming a flat list structure to a tree. Therefore lazy loading is not an easy task to achieve. For example, how to know if a node has childrens if you haven't loaded it already?

Technically using the tree interfaces it should be possible to create a custom tree (implementing ITreeData and so on) that operates like a tree. Maybe the interfaces help you in finding a way to implement lazy loading.
Re: Lazy loading tree, multiple columngrouping [message #1391869 is a reply to message #1391839] Tue, 01 July 2014 10:34 Go to previous messageGo to next message
Dirk Fauth is currently offline Dirk Fauth
Messages: 1227
Registered: July 2012
Senior Member
Quote:
I've read in the current roadmap


BTW, currently we started a discussion about a possible roadmap. We have no current roadmap as we wanted some feedback from our community. If nobody is interested, of course this will become our roadmap.
Re: Lazy loading tree, multiple columngrouping [message #1391920 is a reply to message #1391869] Tue, 01 July 2014 11:51 Go to previous messageGo to next message
Daniel Sievers is currently offline Daniel Sievers
Messages: 2
Registered: July 2014
Junior Member
Hello,

thanks a lot for your quick response.

I will check the interfaces and try to implement the lazy loading.
If I found out something or solve the Problem, I'll let you know and post it here.
Re: Lazy loading tree, multiple columngrouping [message #1403744 is a reply to message #1391920] Fri, 25 July 2014 15:16 Go to previous message
Michel Hertogh is currently offline Michel Hertogh
Messages: 1
Registered: July 2014
Junior Member
Hi Daniel,

Have you found some more information about lazy loading a NatTable tree? I'm looking for the same, but haven't found any example or good practices yet. I was thinking of using a listener on the expand event of a node and to use the TreeList.Format.allowsChildren to tell the tree if the expand icon should be rendered. I'm not sure how NatTable will react, because I think it needs the complete list and builds the tree using TreeList.Format.getPath. I don't know when additional items can be (lazy) loaded.
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