capsul-flask/capsulflask/db.py

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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')
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app.logger.info("loading schema migration scripts from {}".format(schemaMigrationsPath))
for filename in listdir(schemaMigrationsPath):
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result = re.search(r"^\d+_(up|down)", filename)
if not result:
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app.logger.error(f"schemaVersion {filename} must match ^\\d+_(up|down). exiting.")
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exit(1)
key = result.group()
with open(join(schemaMigrationsPath, filename), 'rb') as file:
schemaMigrations[key] = file.read().decode("utf8")
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connection = app.config['PSYCOPG2_CONNECTION_POOL'].getconn()
hasSchemaVersionTable = False
actionWasTaken = False
schemaVersion = 0
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desiredSchemaVersion = 4
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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:
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app.logger.info("no table named schemaversion found in the {} schema. running migration 01_up".format(app.config['DATABASE_SCHEMA']))
try:
cursor.execute(schemaMigrations["01_up"])
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connection.commit()
except:
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app.logger.error("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:
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app.logger.critical("schemaVersion ({}) > desiredSchemaVersion ({}). schema downgrades are not supported yet. exiting.".format(
schemaVersion, desiredSchemaVersion
))
exit(1)
while schemaVersion < desiredSchemaVersion:
migrationKey = "%02d_up" % (schemaVersion+1)
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app.logger.info("schemaVersion ({}) < desiredSchemaVersion ({}). running migration {}".format(
schemaVersion, desiredSchemaVersion, migrationKey
))
try:
cursor.execute(schemaMigrations[migrationKey])
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connection.commit()
except KeyError:
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app.logger.critical("missing schema migration script: {}_xyz.sql".format(migrationKey))
exit(1)
except:
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app.logger.critical("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:
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app.logger.critical("incorrect schema version value \"{}\" after running migration {}, expected \"{}\". exiting.".format(
versionFromDatabase,
migrationKey,
schemaVersion
))
exit(1)
cursor.close()
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app.config['PSYCOPG2_CONNECTION_POOL'].putconn(connection)
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app.logger.info("{} current schemaVersion: \"{}\"".format(
("schema migration completed." if actionWasTaken else "schema is already up to date. "), schemaVersion
))
app.teardown_appcontext(close_db)
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def get_model():
if 'db_model' not in g:
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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):
db_model = g.pop("db_model", None)
if db_model is not None:
db_model.cursor.close()
current_app.config['PSYCOPG2_CONNECTION_POOL'].putconn(db_model.connection)
def my_exec_info_message(exec_info):
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return "{}: {}".format(".".join([exec_info[0].__module__, exec_info[0].__name__]), exec_info[1])