setting up pyramid app: sql engine

development.ini

@@ -0,0 +1,80 @@
+###
+# app configuration
+# https://docs.pylonsproject.org/projects/pyramid/en/latest/narr/environment.html
+###
+
+[app:main]
+use = egg:ordr3
+
+pyramid.reload_templates = true
+pyramid.debug_authorization = false
+pyramid.debug_notfound = false
+pyramid.debug_routematch = false
+pyramid.default_locale_name = en
+pyramid.includes =
+    pyramid_debugtoolbar
+
+sqlalchemy.url = sqlite:///%(here)s/ordr3.sqlite
+
+retry.attempts = 3
+
+# By default, the toolbar only appears for clients from IP addresses
+# '127.0.0.1' and '::1'.
+# debugtoolbar.hosts = 127.0.0.1 ::1
+
+[pshell]
+setup = ordr3.pshell.setup
+
+###
+# wsgi server configuration
+###
+
+[alembic]
+# path to migration scripts
+script_location = ordr3/alembic
+file_template = %%(year)d%%(month).2d%%(day).2d_%%(rev)s
+# file_template = %%(rev)s_%%(slug)s
+
+[server:main]
+use = egg:waitress#main
+listen = localhost:6543
+
+###
+# logging configuration
+# https://docs.pylonsproject.org/projects/pyramid/en/latest/narr/logging.html
+###
+
+[loggers]
+keys = root, ordr3, sqlalchemy
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = INFO
+handlers = console
+
+[logger_ordr3]
+level = DEBUG
+handlers =
+qualname = ordr3
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+# "level = INFO" logs SQL queries.
+# "level = DEBUG" logs SQL queries and results.
+# "level = WARN" logs neither.  (Recommended for production systems.)
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(asctime)s %(levelname)-5.5s [%(name)s:%(lineno)s][%(threadName)s] %(message)s

ordr3/__init__.py

@@ -4,3 +4,16 @@ A rewrite of our CPI ordering system.
 """
 
 __version__ = "0.0.1"
+
+
+from pyramid.config import Configurator
+
+
+def main(global_config, **settings):
+    """ This function returns a Pyramid WSGI application.
+    """
+    with Configurator(settings=settings) as config:
+        config.include("pyramid_jinja2")
+        config.include(".adapters")
+        config.scan()
+    return config.make_wsgi_app()

ordr3/adapters.py

@@ -2,6 +2,7 @@
 
 from datetime import datetime
 
+import zope.sqlalchemy
 from sqlalchemy import (
     Enum,
     Text,
@@ -11,8 +12,9 @@ from sqlalchemy import (
     Integer,
     DateTime,
     ForeignKey,
+    engine_from_config,
 )
-from sqlalchemy.orm import mapper, relationship
+from sqlalchemy.orm import mapper, relationship, sessionmaker
 from sqlalchemy.schema import MetaData
 
 from . import models
@@ -76,6 +78,7 @@ user_table = Table(
 
 
 def start_mappers():
+    """ maps data base tables to model objects """
     mapper(
         models.OrderItem,
         order_table,
@@ -87,3 +90,73 @@ def start_mappers():
     )
     mapper(models.LogEntry, log_table)
     mapper(models.User, user_table)
+
+
+def get_engine(settings, prefix="sqlalchemy."):
+    """ returns a sqlalchemy engine from a settings dict """
+    return engine_from_config(settings, prefix)
+
+
+def get_session_factory(engine):
+    """ returns a sqlalchemy session factory for a db enging """
+    factory = sessionmaker()
+    factory.configure(bind=engine)
+    return factory
+
+
+def get_tm_session(session_factory, transaction_manager):
+    """
+    Get a ``sqlalchemy.orm.Session`` instance backed by a transaction.
+
+    This function will hook the session to the transaction manager which
+    will take care of committing any changes.
+
+    - When using pyramid_tm it will automatically be committed or aborted
+      depending on whether an exception is raised.
+
+    - When using scripts you should wrap the session in a manager yourself.
+      For example::
+
+          import transaction
+
+          engine = get_engine(settings)
+          session_factory = get_session_factory(engine)
+          with transaction.manager:
+              dbsession = get_tm_session(session_factory, transaction.manager)
+
+    """
+    dbsession = session_factory()
+    zope.sqlalchemy.register(
+        dbsession, transaction_manager=transaction_manager
+    )
+    return dbsession
+
+
+def includeme(config):
+    """
+    Initialize the model for a Pyramid app.
+
+    Activate this setup using ``config.include('ordr3.adapters')``.
+
+    """
+    settings = config.get_settings()
+    settings["tm.manager_hook"] = "pyramid_tm.explicit_manager"
+
+    # use pyramid_tm to hook the transaction lifecycle to the request
+    config.include("pyramid_tm")
+
+    # use pyramid_retry to retry a request when transient exceptions occur
+    config.include("pyramid_retry")
+
+    session_factory = get_session_factory(get_engine(settings))
+    config.registry["dbsession_factory"] = session_factory
+
+    # make request.dbsession available for use in Pyramid
+    config.add_request_method(
+        # r.tm is the transaction manager used by pyramid_tm
+        lambda r: get_tm_session(session_factory, r.tm),
+        "dbsession",
+        reify=True,
+    )
+
+    start_mappers()

production.ini

@@ -0,0 +1,68 @@
+###
+# app configuration
+# https://docs.pylonsproject.org/projects/pyramid/en/latest/narr/environment.html
+###
+
+[app:main]
+use = egg:ordr3
+
+pyramid.reload_templates = false
+pyramid.debug_authorization = false
+pyramid.debug_notfound = false
+pyramid.debug_routematch = false
+pyramid.default_locale_name = en
+
+sqlalchemy.url = sqlite:///%(here)s/ordr3.sqlite
+
+retry.attempts = 3
+
+[pshell]
+setup = ordr3.pshell.setup
+
+###
+# wsgi server configuration
+###
+
+[server:main]
+use = egg:waitress#main
+listen = *:6543
+
+###
+# logging configuration
+# https://docs.pylonsproject.org/projects/pyramid/en/latest/narr/logging.html
+###
+
+[loggers]
+keys = root, ordr3, sqlalchemy
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+
+[logger_ordr3]
+level = WARN
+handlers =
+qualname = ordr3
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+# "level = INFO" logs SQL queries.
+# "level = DEBUG" logs SQL queries and results.
+# "level = WARN" logs neither.  (Recommended for production systems.)
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(asctime)s %(levelname)-5.5s [%(name)s:%(lineno)s][%(threadName)s] %(message)s

pyproject.toml

@@ -30,6 +30,7 @@ requires = [
     "pyramid_jinja2 >= 2.7",
     "pyramid_mailer >= 0.15.1",
     "pyramid_tm >= 2.4",
+    "pyramid_retry >= 2.1",
     "sqlalchemy >= 1.3.15",
     "transaction >= 3.0.0",
     "waitress >= 1.4.3",