检查Sqlite3查询是否返回null Flask

Question

我在用Python形成条件以检查对API的响应是否为null时遇到了一些问题。我使用的是Flask和SQLite3模块。下面是我的一个资源片段。

class Sites(Resource):
def get(self, store):
print('Received a request at ADDRESS for Store ' + store )
conn = sqlite3.connect('store-db.db')
cur = conn.cursor()
res = cur.execute('SELECT * FROM Sites WHERE StoreNumber like ' + store)
for r in res:
if r == 'null':
return('No data', 404)
else:
column_names = ["StoreNumber", "Street", "StreetSecondary","City","State", "ZipCode", "ContactNumber", "XO_TN", "RelocationStatus", "StoreType", "Timezone"]
data = [r[0], r[1], r[2], r[3], r[4], r[5], r[6], r[7], r[8], r[9], r[10]]            
datadict = {column_names[itemindex]:item for itemindex, item in enumerate(data)}
return(datadict, 200)

如果我向一个不存在的站点发出请求，返回的值是null，但我尝试捕获它都没有成功，所以我想知道我使用Python检查的方式是否不正确？

我试过r[0] == 'null'、r is None、r == 'null'、r == null和r == Null，但都没有用。

成功请求

HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 333
Access-Control-Allow-Origin: *
Server: Werkzeug/0.14.1 Python/3.7.0
Date: Thu, 15 Nov 2018 15:11:03 GMT
{
"StoreNumber": 42,
"Street": "5000 Robinson Centre Drive",
"StreetSecondary": "",
"City": "Pittsburgh",
"State": "PA",
"ZipCode": "15205",
"ContactNumber": "[phone]",
"XO_TN": "[phone]",
"RelocationStatus": "",
"StoreType": "Dick's Sporting Goods",
"Timezone": "Eastern"
}

没有数据的请求(应返回404(

HTTP/1.0 200 OK
Content-Type: application/json
Content-Length: 5
Access-Control-Allow-Origin: *
Server: Werkzeug/0.14.1 Python/3.7.0
Date: Thu, 15 Nov 2018 15:11:41 GMT
null

Answer 1

cur.rowcount((应具有返回的行数。检查是否大于0(无行(