- `Order.draw()` plots a `Courier`'s path from the
`Order.pickup_address` to the `Order.delivery_address`
- `Path.draw()` plots a `Courier`'s path between any two
`Address` objects
- a `Path` is a better description for an instance of the model
- the `Location`s en route are renamed into `.waypoints`
- generic `assoc` is renamed into `path` in the test suite
Adapt code to prevent new warnings and errors (as of SQLAlchemy 1.4):
- Overlapping foreign key columns could be set in a conflicting way
=> This is prevented by the application logic
=> Ignore the warning by setting a `overlaps` flag
- Transaction already rolled back
=> This only happens when tests cause an `IntegrityError` on purpose
=> Filter away the corresponding warning in the fixture
- Query returns `Row` objects and not scalars
=> Add genexpr to pull out `primary_id`
... from the dev dependencies.
Longer queries in SQLAlchemy get flagged even though they are not
complicated. Other expressions are generally not that complicated.
- as of September 2021, PyCharm is used to write some of the code
- PyCharm's built-in code styler, linter, and type checker issued
some warnings that are resolved in this commit
+ spelling mistakes
+ all instance attributes must be specified explicitly
in a class's __init__() method
=> use `functools.cached_property` for caching
+ make `tuple`s explicit with `(...)`
+ one test failed randomly although everything is ok
=> adjust the fixture's return value (stub for Google Directions API)
+ reformulate SQL so that PyCharm can understand the symbols
- `DistanceMatrix.from_addresses()` takes a variable number of
`Address` objects and creates distance matrix entries for them
- as a base measure, the air distance between two `Address`
objects is calculated
- in addition, an integration with the Google Maps Directions API is
implemented that provides a more realistic measure of the distance
and duration a rider on a bicycle would need to travel between two
`Address` objects
- add a `Location.lat_lng` convenience property that provides the
`.latitude` and `.longitude` of an `Address` as a 2-`tuple`
- the class stores the data of a distance matrix between all addresses
+ air distances
+ bicycle distances
- in addition, the "path" returned by the Google Directions API are
also stored as a JSON serialized sequence of latitude-longitude pairs
- we assume a symmetric graph
