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Yeah our org should really move away from flask-sqlalchemy and be more declarative about what session changes should actually be made on. Being more hands on w

Yeah our org should really move away from flask-sqlalchemy and be more declarative about what session changes should actually be made on. Being more hands on with sqlalchemy is probably the right approach.

danjac 6y ago
Not having touched this stack in a while: what is best current practice for wiring together sqlalchemy and flask (including unit tests)?
- returningfory2 6y ago
  Potentially don't wire them together? That is, isolate them in separate parts of the code. I always found Flask-SQLAlchemy a strange approach because it ties opposite and somewhat orthogonal parts of the request lifecycle together. When requests-to-data-transactions is a 1-1 relationship it's a convenience, but once you step out of that I think it's better to do things by hand. My main app has a simple layer structure of "request > business logic > data layer". All of the business logic functions start a SQLAlchemy transaction using a Python decorator that is ~10 lines of SQLAlchemy code.
- ergo14 6y ago
  Check out how things are wired with in this Pyramid cookie cutter. https://github.com/Pylons/pyramid-cookiecutter-starter/blob/latest/%7B%7Bcookiecutter.repo_name%7D%7D/%7B%7Bcookiecutter.repo_name%7D%7D/sqlalchemy_models/__init__.py https://github.com/Pylons/pyramid-cookiecutter-starter/blob/... I think same approach should work well for flask - just tie the session to the request object on first access. Side note: I think we met on IRC few years ago ;-)
  - luhn 6y ago
    There is a lot going on in that cookie cutter. The “transaction” library for transaction management, wired into Pyramid with pyramid_tm, wired into SQLAlchemy with zope.sqlalchemy. Works nicely for Pyramid, but I don’t know how that translates to Flask.
    - ergo14 6y ago
      Doesn't, I wanted to show how it can be wired to request.
    - jordic 6y ago
      Think on it like a middleware that wraps a transaction. It's fine, till you start consuming other Io based services (elastic/solar/...) And you find that this blocks one connection per request..
jononor 6y ago
I passed on flask-sqlalchemy because it was not obvious to me how it worked together, and I did not see the value over just using Flask and SQLAlchemy with no special integration. Has worked now a couple of years in, will see how it is in a few years more.

danjac 6y ago

Not having touched this stack in a while: what is best current practice for wiring together sqlalchemy and flask (including unit tests)?

returningfory2 6y ago
Potentially don't wire them together? That is, isolate them in separate parts of the code. I always found Flask-SQLAlchemy a strange approach because it ties opposite and somewhat orthogonal parts of the request lifecycle together. When requests-to-data-transactions is a 1-1 relationship it's a convenience, but once you step out of that I think it's better to do things by hand. My main app has a simple layer structure of "request > business logic > data layer". All of the business logic functions start a SQLAlchemy transaction using a Python decorator that is ~10 lines of SQLAlchemy code.
ergo14 6y ago
Check out how things are wired with in this Pyramid cookie cutter. https://github.com/Pylons/pyramid-cookiecutter-starter/blob/latest/%7B%7Bcookiecutter.repo_name%7D%7D/%7B%7Bcookiecutter.repo_name%7D%7D/sqlalchemy_models/__init__.py https://github.com/Pylons/pyramid-cookiecutter-starter/blob/... I think same approach should work well for flask - just tie the session to the request object on first access. Side note: I think we met on IRC few years ago ;-)
- luhn 6y ago
  There is a lot going on in that cookie cutter. The “transaction” library for transaction management, wired into Pyramid with pyramid_tm, wired into SQLAlchemy with zope.sqlalchemy. Works nicely for Pyramid, but I don’t know how that translates to Flask.
  - ergo14 6y ago
    Doesn't, I wanted to show how it can be wired to request.
  - jordic 6y ago
    Think on it like a middleware that wraps a transaction. It's fine, till you start consuming other Io based services (elastic/solar/...) And you find that this blocks one connection per request..

jononor 6y ago

I passed on flask-sqlalchemy because it was not obvious to me how it worked together, and I did not see the value over just using Flask and SQLAlchemy with no special integration. Has worked now a couple of years in, will see how it is in a few years more.