import psycopg2 import re import sys from urllib.parse import urlparse from os import listdir from os.path import isfile, join from psycopg2 import pool from flask import current_app from flask import g from capsulflask.db_model import DBModel def init_app(app): databaseUrl = urlparse(app.config['DATABASE_URL']) app.config['PSYCOPG2_CONNECTION_POOL'] = psycopg2.pool.SimpleConnectionPool( 1, 20, user = databaseUrl.username, password = databaseUrl.password, host = databaseUrl.hostname, port = databaseUrl.port, database = databaseUrl.path[1:] ) schemaMigrations = {} schemaMigrationsPath = join(app.root_path, 'schema_migrations') print("loading schema migration scripts from {}".format(schemaMigrationsPath)) for filename in listdir(schemaMigrationsPath): key = re.search(r"^\d+_(up|down)", filename).group() with open(join(schemaMigrationsPath, filename), 'rb') as file: schemaMigrations[key] = file.read().decode("utf8") connection = app.config['PSYCOPG2_CONNECTION_POOL'].getconn() hasSchemaVersionTable = False actionWasTaken = False schemaVersion = 0 desiredSchemaVersion = 2 cursor = connection.cursor() cursor.execute(""" SELECT table_name, table_schema FROM information_schema.tables WHERE table_schema = '{}' """.format(app.config['DATABASE_SCHEMA'])) rows = cursor.fetchall() for row in rows: if row[0] == "schemaversion": hasSchemaVersionTable = True if hasSchemaVersionTable == False: print("no table named schemaversion found in the {} schema. running migration 01_up".format(app.config['DATABASE_SCHEMA'])) try: cursor.execute(schemaMigrations["01_up"]) connection.commit() except: print("unable to create the schemaversion table because: {}".format(my_exec_info_message(sys.exc_info()))) exit(1) actionWasTaken = True cursor.execute("SELECT Version FROM schemaversion") schemaVersion = cursor.fetchall()[0][0] if schemaVersion > desiredSchemaVersion: print("schemaVersion ({}) > desiredSchemaVersion ({}). schema downgrades are not supported yet. exiting.".format( schemaVersion, desiredSchemaVersion )) exit(1) while schemaVersion < desiredSchemaVersion: migrationKey = "%02d_up" % (schemaVersion+1) print("schemaVersion ({}) < desiredSchemaVersion ({}). running migration {}".format( schemaVersion, desiredSchemaVersion, migrationKey )) try: cursor.execute(schemaMigrations[migrationKey]) connection.commit() except KeyError: print("missing schema migration script: {}_xyz.sql".format(migrationKey)) exit(1) except: print("unable to execute the schema migration {} because: {}".format(migrationKey, my_exec_info_message(sys.exc_info()))) exit(1) actionWasTaken = True schemaVersion += 1 cursor.execute("SELECT Version FROM schemaversion") versionFromDatabase = cursor.fetchall()[0][0] if schemaVersion != versionFromDatabase: print("incorrect schema version value \"{}\" after running migration {}, expected \"{}\". exiting.".format( versionFromDatabase, migrationKey, schemaVersion )) exit(1) cursor.close() app.config['PSYCOPG2_CONNECTION_POOL'].putconn(connection) print("{} current schemaVersion: \"{}\"".format( ("schema migration completed." if actionWasTaken else "schema is already up to date. "), schemaVersion )) app.teardown_appcontext(close_db) def get_model(): if 'model' not in g: connection = current_app.config['PSYCOPG2_CONNECTION_POOL'].getconn() cursor = connection.cursor() g.db_model = DBModel(connection, cursor) return g.db_model def close_db(e=None): model = g.pop("model", None) if model is not None: model.cursor.close() current_app.config['PSYCOPG2_CONNECTION_POOL'].putconn(model.connection) def my_exec_info_message(exec_info): return "{}: {}".format(".".join([exec_info[0].__module__, exec_info[0].__name__]), exec_info[1])