3 commits

Author	SHA1	Message	Date
Alexander Hess	078355897a	Fix missing unique constraint drop	2021-01-05 22:32:24 +01:00
Alexander Hess	776112d609	Add Grid.gridify() constructor ... - the purpose of this constructor method is to generate all `Pixel`s for a `Grid` that have at least one `Address` assigned to them - fix missing `UniqueConstraint` in `Grid` class => it was not possible to create two `Grid`s with the same `.side_length` in different cities - change the `City.viewport` property into two separate `City.southwest` and `City.northeast` properties; also add `City.total_x` and `City.total_y` properties for convenience	2021-01-05 18:58:48 +01:00
Alexander Hess	f996376b13	Add ORM models for the pixel grids ... - add Grid, Pixel, and AddressPixelAssociation ORM models - each Grid belongs to a City an is characterized by the side_length of all the square Pixels contained in it - Pixels aggregate Addresses => many-to-many relationship (that is modeled with SQLAlchemy's Association Pattern to implement a couple of constraints)	2021-01-03 19:33:36 +01:00