10-feature-add-items.md

phase 10 — feature: add items

prerequisite

phase 09; understand DATA_MODEL.md itempriceid.

goal

user picks an item; you insert OrderItem with valid ItemPriceID and Quantity; redirect details.

steps you do

1. get: build list of purchasable rows — at minimum each row shows item name + itempriceid as hidden or route.
2. choose pricing rule: which ItemPrice row for “now” (document in comment).
3. post: new OrderItem { OrderID = id, ItemPriceID = ..., Quantity = n, ExtendedPrice = ... }.
4. SaveChanges(); RedirectToAction("Details", new { id }).

sanity check

refresh details; line persists; totals plausible.

common mistakes

• quantity default 0
• wrong price row — extended price does not match unit * qty

reflection

why does schema use ItemPriceID instead of raw ItemID?