我正在使用 Python 和 MySqlDB 开发 Google App Engine 项目,App Engine 要求我将 Message 对象返回到端点。
这是返回类的外观:
class ReturningClass(messages.Message):
"""Return Column values stored here."""
ID = messages.IntegerField(1)
Locality_Name = messages.StringField(2)
Pincode = messages.IntegerField(3)
No_of_LL = messages.IntegerField(4)
No_of_Hospitals = messages.IntegerField(5)
No_of_Hotels = messages.IntegerField(6)
And So on...
我想动态获取大约 30 列。
下面是 ReturningClass 的集合
class ReturningClassCollection(messages.Message):
"""Collection of ReturningClass objects."""
items = messages.MessageField(ReturningClass, 1, repeated=True)
这是实际执行所有返回的主类:
class MainClass(webapp2.RequestHandler):
def get(self,Columns):
if (os.getenv('SERVER_SOFTWARE') and
os.getenv('SERVER_SOFTWARE').startswith('Google App Engine/')):
db = MySQLdb.connect(unix_socket='/cloudsql/' + _INSTANCE_NAME, db='DatabaseName', user='root')
else:
db = MySQLdb.connect(host='127.0.0.1', port=3306, db='DatabaseName', user='root')
cursor = db.cursor()
ReturningArray=ReturningClassCollection()
query="SELECT %s FROM DemoTable"%(Columns)
cursor.execute(query)
for result in cursor.fetchall():
ReturningArray.items.append(ReturningClass(
ID = result[0] ,
Locality_Name = cgi.escape(result[1]),
Pincode = result[2],
No_of_LL= result[3],
No_of_Hospitals = result[4]
))
cursor.close()
db.close()
return ReturningArray
如果我为选择语句提供 5 个硬编码到返回游标中的预期列值,则此方法有效。
前任:
query="SELECT ID,Locality_Name,Pincode,No_of_LL,No_of_Hospitals,No_of_Hotels
FROM DemoTable"
但如果我这样做:
query="SELECT ID,Locality_Name
FROM DemoTable"
我得到一个:
IndexError: tuple index out of range
我如何获得
for result in cursor.fetchall():
ReturningArray.items.append(ReturningClass(
??
))
只返回 select 语句中的列?