[Sourcing] Tree table: New ability to load child rows dynamically using infinite scrolling

[yixuan-liu]

Is this a bug, enhancement, or feature request?

Enhancement

Briefly describe your proposal.

As of now with the default table datasource, we could not trigger infinite scrolling to load a large number of child nodes chunk by chunk with size set by the pageSize table property.​

We'd like to dynamically keep loading the child rows of an already rendered parent row, using infinite scrolling where user will see the busy indicator overlay.​

For instance, consider the following scenario when we load the following tree table with everything collapsed:

Item 1
   Item 1.1
   Item 1.2
   Item 1.3
   Item 1.4
   Item 1.5

---

Each of Items 1.1-1.5 has a large number of child rows which are currently collapsed. And when user clicks on Item 1.1 to expand, we'd like to call our service API to fetch the details of those child rows associated under Item 1.1, using infinite scrolling so that we could load on demand, chunk by chunk.

Item 1
   Item 1.1
     Item 1.1.1
     Item 1.1.2
     ....
     ....
     (incoming child row data through API)
     ....
     ....
   Item 1.2
   Item 1.3
   Item 1.4
   Item 1.5

However, as of now, we could achieve such functionality as the newly fetched chunk data of child rows could not be correctly rendered and attached to the parent node Item 1, and it currently requires us to manually invoke table component's fetch() method in order to update the table view with those newly fetched child rows data.

Basically, what we'd like to see if that when we expand on certain parent row/node, we will load an initial chunk of, say, 20 child rows under that parent. Then, as user scrolls and reaches the end of those loaded child rows, we should trigger a loading event where we can invoke our service API to fetch the next 20 child row data.

Which versions of Angular and Fundamental Library for Angular are affected? (If this is a feature request, use current version.)

Current version.

[droshev]

@yixuan-liu We couldn't figure out what exactly the issue is and what the expectation is. Could you elaborate a little bit more? thanks

[yixuan-liu]

@yixuan-liu We couldn't figure out what exactly the issue is and what the expectation is. Could you elaborate a little bit more? thanks

Sure Deno... just added more details in issue description... Thanks!

[fkolar]

this issue is the same root cause as: #9746, #9238, #9926

We are working on the solution to improve things on the approach side. There are two major problems:

• Bypassing Table functionality in terms of DataSource and DataProvider usage
• Cache excessive pipe calls so we can pre-calculate a state for columns