Patterns, gotchas and small wins from fifteen-odd years of .NET and web work — the Regira packages and modules, entity pipelines, editorial front-ends and everything between.
Show the flat list an API returns as a tree users can expand, select and drag to a new parent. No recursive component, and illegal drops are refused in the browser before they reach the server.
Answer 'everything under X' for category trees, org charts and folders, at any depth. Three approaches, from one that works on any database to one that scales to millions of rows, and how to pick.
A quick look at turning a flat collection with parent references into a navigable hierarchy, without writing recursion yourself.
Answer who reported to whom on any past date from the data you already store, with no history tables and no migrations. One dated relationship table and a single filter do it; Westeros supplies three centuries of test data.
One table for every customer, supplier and employee, with roles and alliances as dated relationships instead of extra tables. Tested on Westeros, where everyone knows who betrayed whom and when.