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.
When two people save the same record, the second save is refused instead of quietly erasing the first, whichever database the application runs on. The second user reloads and re-applies their change.
Saving a record from a small form should never wipe the items attached to it, while the full edit screen can still remove them all. How an API tells an omitted list from an empty one, and what a form sends for a row the user removed.
Keep an update from blanking a field the form never showed, such as a reference code, a close date or a total. What causes it, why every line involved passes review, and the one-line declaration that prevents it.
One place for each rule a save must obey, so it holds whether a user, an import or a nightly job did the saving. Required fields, timestamps and a code that never changes stop being scattered across controllers.
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.
One customer must never see another's rows, in any list, count or endpoint, including the one added next year. Seven requirements that make that a property of the system, and which of them no library can meet for you.
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.
Let users ask for this or that, one brand or anything overdue, in a list that still pages and sorts like every other. How to offer 'or' without a flag nobody trusts.
Rules that must hold for every record, such as hiding deleted data or showing each customer only their own, set up once and applied everywhere. They also cover the endpoint added next year, and nobody skips them by accident.
A search box that finds 'Café' when someone types 'Cafe', and 'Mercedes-Benz' for 'mercedes', without extra work on every search. The trick: tidy the text once when it is saved, not each time someone searches.
Let users delete a record and still get it back: it disappears from every screen, stays in the database, and restores in one click. A recycle bin and an audit view come with it, no extra code.
Lists that users sort by several columns, that load related data only when a screen asks, and that never hand a client a million rows. Declared once, applied to every list.