Question

在不知道json的结构的情况下，如何从数据库查询中返回json对象？所有的信息都存在，我只是无法弄清楚如何构建对象。

import MySQLdb
import json
db = MySQLdb.connect( host, user, password, db)
cursor = db.cursor()
cursor.execute( query )
rows = cursor.fetchall()

field_names = [i[0] for i in cursor.description]
json_string = json.dumps( dict(rows) )

print field_names[0]
print field_names[1]
print json_string

db.close()

计数

严重性

{“321”：“7.2”，“1”：“5.0”，“5”：“4.3”，“7”：“6.8”，“1447”：“9.3”，“176”：“10.0 “}

json对象看起来像：

{"data":[{"count":"321","severity":"7.2"},{"count":"1","severity":"5.0"},{"count":"5","severity":"4.3"},{"count":"7","severity":"6.8"},{"count":"1447","severity":"9.3"},{"count":"176","severity":"10.0"}]}

Answer 1

1-您可以使用pymsql DictCursor：

import pymysql
connection = pymysql.connect(db="test")
cursor = connection.cursor(pymysql.cursors.DictCursor)
cursor.execute("SELECT ...")
row = cursor.fetchone()
print row["key"]

2- MySQLdb还包括您可以使用的DictCursor。您需要在建立连接时传递cursorclass=MySQLdb.cursors.DictCursor。

import MySQLdb
import MySQLdb.cursors
connection = MySQLdb.connect(db="test",cursorclass=MySQLdb.cursors.DictCursor)
cursor = connection.cursor()
cursor.execute("SELECT ...")
row = cursor.fetchone()
print row["key"]

Answer 2

The problem you are encountering happens because you only turn the fetched items into dicts, without their description.

dict in python expects either another dict, or an iterable returning two-item tuples, where for each tuple the first item will be the key, and the second the value.

Since you only fetch two columns, you get the first one (count) as key, and the second (severity) as value for each fetched row.

What you want to do is also combine the descriptions, like so:

json_string = json.dumps([
{description: value for description, value in zip(field_names, row)}
for row in rows])

Answer 3

I got this to work using Collections library, although the code is confusing:

import MySQLdb
import json
import collections
db = MySQLdb.connect(host, user, passwd, db)
cursor = db.cursor()
cursor.execute( query )
rows = cursor.fetchall()
field_names = [i[0] for i in cursor.description]

objects_list = []
for row in rows:
    d = collections.OrderedDict()
    d[ field_names[0] ] = row[0]
    d[ field_names[1] ] = row[1]
    objects_list.append(d)

json_string = json.dumps( objects_list )

print json_string

db.close()

[{"count": 176, "severity": "10.0"}, {"count": 1447, "severity": "9.3"}, {"count": 321, "severity": "7.2"}, {"count": 7, "severity": "6.8"}, {"count": 1, "severity": "5.8"}, {"count": 1, "severity": "5.0"}, {"count": 5, "severity": "4.3"}]

从sql数据库游标构建json数据

3 个答案: