我喜欢提取特定的密钥并将其存储到列表中。到目前为止,我已经能够从MariaDB中读取并将行存储为字典(我更喜欢将输出作为JSON):
import pymysql
import simplejson as json
import collections
import credentials_global
conn = pymysql.connect(
host=credentials_global.mariadb_dev_ip_address,
user=credentials_global.mariadb_dev_username,
password=credentials_global.mariadb_dev_password,
port=credentials_global.mariadb_dev_port,
database=credentials_global.mariadb_dev_db_ticketing,
)
cursor = conn.cursor()
cursor.execute("select a, b, c, d, e, f from master.orders where c = 215")
rows = cursor.fetchall()
objects_list = []
for row in rows:
d = collections.OrderedDict()
d["a"] = row[0]
d["b"] = row[1]
d["c"] = row[2]
d["d"] = row[3]
d["e"] = row[4]
d["f"] = row[5]
objects_list.append(d)
j = json.dumps(objects_list)
print(j)
这将产生输出:
[
{
"a": 4153,
"b": "NO_EFFECT",
"c": "none",
"d": "Medium",
"e": 1,
"f": "No Remarks",
},
{
"a": 4154,
"b": "SIGNIFICANT",
"c": "none",
"d": "Low",
"e": 1,
"f": "Test Message",
},
]
我喜欢提取所有出现的f
。我已经尝试过:
for key, value in d.items():
print(value)
此输出:
4153
NO_EFFECT
none
Medium
1
No Remarks
4154
SIGNIFICANT
none
Low
1
Test Message
我更喜欢只提取f
,以便输出类似于[No Remarks, Test Message]
(我假设序列保持不变)。有人可以协助我实现目标或在哪里寻找目标吗?
谢谢
for obj in objects_list:
print(obj['f'])
OrderedDict保留键的顺序(a b c ...)。此输出中的顺序来自objects_list中的顺序。
要在输出列表上获取它:
only_f_fields = [ obj['f'] for obj in objects_list ]
我认为您寻找的答案是
for key, value in d.items():
print(value[0]['f'])
列表中的第一个元素0,在该列表中,字典中的元素f。
假设接收到的输出在列表中:ex = [{"a": 4153, "b": "NO_EFFECT", "c": "none", "d": "Medium", "e": 1, "f": "No Remarks"},
{"a": 4154, "b": "SIGNIFICANT", "c": "none", "d": "Low", "e": 1, "f": "Test Message"}]
我们可以执行2种方法,其中一种通常不假定按键顺序重复进行迭代,另一种可以按顺序进行迭代。
f_list = list()
for val in ex:
for k, v in val.items():
if k == "f":
f_list.append(v)
print(f_list)
输出:['No Remarks', 'Test Message']
f_list = list()
for val in ex:
f_list.append(val["f"])
print(f_list)
输出:['No Remarks', 'Test Message']