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https://github.com/ets-labs/python-dependency-injector.git
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72 lines
2.2 KiB
Python
72 lines
2.2 KiB
Python
"""`ExternalDependency` providers example."""
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import sqlite3
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import contextlib
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import dependency_injector as di
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class UserService(object):
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"""Example class UserService.
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UserService has dependency on DBAPI 2.0 database connection.
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"""
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def __init__(self, database):
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"""Initializer.
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Database dependency need to be injected via init arg.
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"""
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self.database = database
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def init_database(self):
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"""Initialize database, if it has not been initialized yet."""
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with contextlib.closing(self.database.cursor()) as cursor:
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cursor.execute("""
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CREATE TABLE IF NOT EXISTS users(
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id INTEGER PRIMARY KEY AUTOINCREMENT,
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name VARCHAR(32)
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)
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""")
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def create(self, name):
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"""Create user with provided name and return his id."""
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with contextlib.closing(self.database.cursor()) as cursor:
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cursor.execute('INSERT INTO users(name) VALUES (?)', (name,))
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return cursor.lastrowid
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def get_by_id(self, id):
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"""Return user info by user id."""
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with contextlib.closing(self.database.cursor()) as cursor:
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cursor.execute('SELECT id, name FROM users WHERE id=?', (id,))
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return cursor.fetchone()
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# Database and UserService providers:
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database = di.ExternalDependency(instance_of=sqlite3.dbapi2.Connection)
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users_service_factory = di.Factory(UserService,
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database=database)
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# Out of library's scope.
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#
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# Setting database provider:
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database.provided_by(di.Singleton(sqlite3.dbapi2.Connection,
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database=':memory:',
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timeout=30,
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detect_types=True,
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isolation_level='EXCLUSIVE'))
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# Creating UserService instance:
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users_service = users_service_factory()
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# Initializing UserService database:
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users_service.init_database()
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# Creating test user and retrieving full information about him:
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test_user_id = users_service.create(name='test_user')
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test_user = users_service.get_by_id(test_user_id)
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# Making some asserts:
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assert test_user['id'] == 1
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assert test_user['name'] == 'test_user'
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