baya-monorepo/archive/product/data-model/02-geography.md

Domain 2 — Geographic Data

← Database Model

provinces / cities / districts [CORE]/[MVP]

Role: The geo hierarchy backing service areas, addresses, and search. Why a table, not a static list: new cities/districts launch without a deploy, and sort_order/is_active drive ordered, toggleable dropdowns. districts map to Tehran's 22 municipal districts or major neighborhoods elsewhere; they are optional (a nurse can cover a whole city). Fields unchanged. Relations: provinces 1:N cities 1:N districts; referenced by customer_addresses and nurse_service_areas.

nurse_service_areas [CORE]

Role: Where a nurse will travel. A row with district_id = NULL means the entire city. Why a join table (not a radius): Iranian nurses think in named districts, not GPS radii; this also drives the geographic filter in search cheaply. Unchanged, with UNIQUE(nurse_id, city_id, district_id). Relations: N:1 → nurse_profiles, cities, districts.

As-built (backend-phase-4): the geo hierarchy lives in a geo schema (Provinces/Cities/ Districts/NurseServiceAreas), seeded via HasData with all 31 provinces, each province's capital city, and Tehran's 22 مناطق. Because SQL Server treats NULLs as distinct in a unique index, the whole-city (district_id = NULL) uniqueness is enforced with a filtered-index pair — UNIQUE(nurse_id, city_id) WHERE district_id IS NULL AND deleted_at IS NULL plus UNIQUE(nurse_id, city_id, district_id) WHERE district_id IS NOT NULL AND deleted_at IS NULL — so both a duplicate whole-city row and a duplicate city+district row are rejected (surfaced as 409), while a soft-removed area can be re-declared. Public lookups are cached and filter is_active at every level (a deactivated parent hides its children); geocoding is behind the mocked IGeocoder seam.