我有課程可以連接到我的數據庫。import psycopg2, psycopg2.extensionsfrom parseini import configimport pandas as pd, pandas.io.sql as sqlioclass MyDatabase: def __init__(self, name='mydb.ini'): self.params = config(filename=name) self.my_connection = psycopg2.connect(**self.params) self.my_cursor = self.my_connection.cursor() def fetch_all_as_df(self, sql_statement): return sqlio.read_sql_query(sql_statement, self.my_connection) def df_to_sql(self, df): table = 'sometable' return sqlio.to_sql(df, table, self.my_connection) def __del__(self): self.my_cursor.close() self.my_connection.close()在我的案例中，如何重新連接到數據庫并處理 psycopg2.OperationalError？
1 回答
飲歌長嘯
TA貢獻1951條經驗 獲得超3個贊
psycopg2.InterfaceError您可以制作一個裝飾器，在或psycopg2.OperationalError被提升時嘗試重新連接。
這只是它如何工作的一個例子，可能需要調整：
import time
from functools import wraps
import psycopg2, psycopg2.extensions
def retry(fn):
@wraps(fn)
def wrapper(*args, **kw):
cls = args[0]
for x in range(cls._reconnectTries):
print(x, cls._reconnectTries)
try:
return fn(*args, **kw)
except (psycopg2.InterfaceError, psycopg2.OperationalError) as e:
print ("\nDatabase Connection [InterfaceError or OperationalError]")
print ("Idle for %s seconds" % (cls._reconnectIdle))
time.sleep(cls._reconnectIdle)
cls._connect()
return wrapper
class MyDatabase:
_reconnectTries = 5
_reconnectIdle = 2 # wait seconds before retying
def __init__(self, name='mydb.ini'):
self.my_connection = None
self.my_cursor = None
self.params = config(filename=name)
self._connect()
def _connect(self):
self.my_connection = psycopg2.connect(**self.params)
self.my_cursor = self.my_connection.cursor()
@retry
def fetch_all_as_df(self, sql_statement):
return sqlio.read_sql_query(sql_statement, self.my_connection)
@retry
def dummy(self):
self.my_cursor.execute('select 1+2 as result')
return self.my_cursor.fetchone()
@retry
def df_to_sql(self, df):
table = 'sometable'
return sqlio.to_sql(df, table, self.my_connection)
def __del__(self):
# Maybe there is a connection but no cursor, whatever close silently!
for c in (self.my_cursor, self.my_connection):
try:
c.close()
except:
pass
db = MyDatabase()
time.sleep(30) # some time to shutdown the database
print(db.dummy())
輸出：
Database Connection [InterfaceError or OperationalError]
Idle for 2 seconds
Database Connection [InterfaceError or OperationalError]
Idle for 2 seconds
Database Connection [InterfaceError or OperationalError]
Idle for 2 seconds
Database Connection [InterfaceError or OperationalError]
Idle for 2 seconds
(3,)
注意：_connect它本身沒有修飾，所以這段代碼假定初始連接總是有效！
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