= Entity-Relationship Model v.01 =

== Diagram ==

[[Image(ERModel_v01.png, width=100%)]]

Source file: [attachment:ERModel_v01.xml]

== Data requirements ==

=== Entities ===

==== Reports ====
Represents a single communal problem reported by a citizen (damaged road, broken street light, waste...). It is the central entity of the system because photos, status changes, comments and assignments all refer to a report.

'''Candidate keys:''' report_id is the only candidate key. No natural attribute uniquely identifies a report, so a generated numeric identifier is used as the primary key.

'''Attributes:'''
 * report_id - numeric, required, auto-generated
 * description - text, required
 * location_text - text, optional (manually entered address)
 * latitude - numeric, optional, between -90 and 90
 * longitude - numeric, optional, between -180 and 180
 * status - text, required, one of: submitted, received, in_progress, resolved, rejected
 * priority - text, required, one of: low, medium, high, urgent
 * created_at - date and time, required

At least one of location_text or latitude/longitude must be entered.

==== Citizens ====
...

=== Relationships ===

==== Submits (Citizens - Reports) ====
Each report is submitted by exactly one citizen, and a citizen can submit many reports. Participation of Reports is total, because a report cannot exist without its author.

==== Classifies (Categories - Reports) ====
...

== Entity-Relationship Model History ==

 * '''v01''' - Initial version of the ER model.