Lists, Trees, Repeaters, and Hierarchical Data

Mastering the Control LibraryModule 4The lesson guide, the walkthrough video, the knowledge check and the hands-on lab this sample was built from are on learnwisej.com — free, with an AI tutor in every lesson.

Open the course

This example is the Lists and Trees section is the document explorer — a TreeView that loads only the top level and fetches each branch in AfterExpand, a ListView in virtual mode whose VirtualListSize comes from a server-side DocumentPage, one ImageList shared by both, and a DocumentDetailControl UserControl that receives a finished DocumentModel.

The shell and the earlier sections come from Modules 1–3. This module adds Services/DocumentService.cs, four models, ListsTrees/, wwwroot/icons/ and docs/ExplorerNotes.md.

The source of this sample

iceteagroup/LearnWisej-SamplesMastering the Control Library Course/Module 4

Browse this folder on GitHub

Or clone it: git clone https://github.com/iceteagroup/LearnWisej-Samples.git — then open OperationsConsole.slnx in Visual Studio and press F5.

Run it

cd "LearnWisej-Samples/Mastering the Control Library Course/Module 4/OperationsConsole"
dotnet run -f net10.0 --urls http://localhost:5704

Then open http://localhost:5704 and select Lists and Trees. Run from the project folder: the static file server serves it, which is how wwwroot/icons/*.svg reaches the browser.

The data

DocumentService generates 557 documents in 6 top-level and 12 sub-categories, in memory, with a fixed seed. Three folders are called "Contracts" (categories 7, 10, 13); Contoso ▸ Contracts holds 312 documents; two categories are empty and Archive 2019-2023 has no children; every 37th document is flagged. Every call takes ~300 ms so the loading state is visible.

What to try

Action	What you should see
Open Lists and Trees	six collapsed folder nodes
Expand Contoso	only Contoso's children load
Expand Archive 2019-2023	no children arrive; amber status "Archive 2019-2023" has no sub-categories.
Select Contoso ▸ Contracts	the list shows the loader, then 312 rows; the footer reads 8 of 312 items created (however many rows fit)
Select Fabrikam ▸ Contracts	same folder text, 36 different documents
Pick a document	the detail card fills; the StatusBar shows Record: DOC-000312; a flagged document shows a red status and the warning icon
Select Shared templates ▸ Contract templates	the amber No documents in this category band
Tick Simulate service failure, then expand or select	red status, an AlertBox, a friendly message; the list is never half-built. Untick and try again to recover
Refresh on the ToolBar	the tree reloads the top level

Where things live

OperationsConsole/
├─ Sections/ListsTreesPage.cs / .Designer.cs   lazy tree, virtual list, selection → service → detail
├─ ListsTrees/DocumentDetailControl.cs         Show(DocumentModel) + ShowMessage(string)
├─ Models/CategoryNode, DocumentSummary, DocumentPage, DocumentModel
├─ Services/DocumentService.cs                 GetTopCategories / GetChildren / GetDocumentPage / GetDocument
├─ wwwroot/icons/                              folder, contract, invoice, drawing, warning (16×16 SVG)
└─ docs/ExplorerNotes.md                       data shape → control, identity rule, lazy + virtual, what breaks at 10×

Known simplifications

• DocumentPage holds the whole category (Items.Count == Total); ExplorerNotes.md §5 names this as the first fix at 10×.
• ListView.FullRowSelect does not exist in Wisej.NET 4.1; MultiSelect = false + SelectionMode.One is the equivalent.
• PrefetchItems = 0 on purpose, so the created-items counter shows exactly what the visible rows cost.