问题描述
我正在使用循环获取fetchone()的内容,每次代码读取fetchone()时,光标就会移至下一行.我知道我需要小心.我正在使用在 https:中找到的示例: //dev.mysql.com/doc/connector-python/zh-CN/connector-python-api-mysqlcursor-fetchone.html 当我有多于一行的行时有效,但只有一行时会出现错误
I am using a loop to get the contents of fetchone(), every time code reads fetchone() the cursor moves to the next row. I understand that I need to be careful. I am using the example found here https://dev.mysql.com/doc/connector-python/en/connector-python-api-mysqlcursor-fetchone.html this works when I have more then one row but when there is a single row I get an error
for k, v in cur.fetchone().items():
AttributeError: 'NoneType' object has no attribute 'items'
两个相关功能
def dict_factory(cursor, row):
d = {}
for idx, col in enumerate(cursor.description):
d[col[0]] = row[idx]
return d
def open_sql(sql_folder, sql_name, sql_table):
# databases are located at /work/jmjohnso1/db_project
path_name = os.path.join(sql_folder,sql_name).strip()
con = lite.connect(path_name)
con.row_factory = dict_factory
cur = con.cursor()
cur.execute('SELECT * FROM ' + sql_table)
dict_contents = defaultdict(list)
for row in cur:
for k, v in cur.fetchone().items():
dict_contents[k].append(v)
con.close()
print(dict_contents)
return dict_contents
如果您需要完整的代码:
In case you want the entire code:
# python3.5
# pymongo version 3.2.2
# MongoDB shell version: 3.0.11
import os
import pymongo
from pymongo import MongoClient
import sqlite3 as lite
import pyewf
import hashlib
from itertools import chain
from collections import defaultdict
import pprint
def list_sql_db(folder):
# need a list for multiprocessing so I made a file.
file_name = os.path.join(folder, 'sql_db')
if not os.path.isfile(file_name):
with open (file_name, 'w') as line:
for (dirpath, dirs, files) in os.walk(folder):
for name in files:
line.write(name + '\n')
return file_name
def dict_factory(cursor, row):
d = {}
for idx, col in enumerate(cursor.description):
d[col[0]] = row[idx]
return d
def open_sql(sql_folder, sql_name, sql_table):
# databases are located at /work/jmjohnso1/db_project
path_name = os.path.join(sql_folder,sql_name).strip()
con = lite.connect(path_name)
con.row_factory = dict_factory
cur = con.cursor()
cur.execute('SELECT * FROM ' + sql_table)
dict_contents = defaultdict(list)
for row in cur:
for k, v in cur.fetchone().items():
dict_contents[k].append(v)
con.close()
print(dict_contents)
return dict_contents
def insert_tsk_mongo(sql_folder, sql_name, sql_table):
client = MongoClient() # connect to mongodb
db = client.nus # make or use a db called nus
contents = open_sql(sql_folder, sql_name, sql_table)
collection = sql_name.strip().replace('-','_') # because mongo will write but not read a collection with -
# document_id = db[collection].insert({ # sql_name is the hard drive name
# sql_table:
# contents
# })
###############################################################################
sql_folder = '/work/jmjohnso1/db_project'
# sql_tables = ['tsk_fs_info', 'tsk_image_info',
# 'tsk_db_info ', 'tsk_image_names',
# 'tsk_file_layout', 'tsk_objects',
# 'tsk_files', 'tsk_vs_info', 'tsk_vs_parts']
sql_tables = ['tsk_fs_info']
sql_folder_name = list_sql_db(sql_folder)
with open (sql_folder_name, 'r') as read:
sql_names = read.readlines()
for sql_name in sql_names:
for sql_table in sql_tables:
insert_tsk_mongo(sql_folder, sql_name, sql_table)
break
推荐答案
您要获取行两次,一次是使用for row in cur:
循环,然后是使用cur.fetchone()
循环.在最后一行,要用完的行已用完,因此返回了None
.
You are fetching rows twice, once with the for row in cur:
loop, then in the loop with cur.fetchone()
. At the last row, you have run out of rows to fetch, so None
is returned.
已经游标游标时,不需要使用cur.fetchone()
.只需放下cur.fetchone()
调用,并使用您已经通过for
提取的行:
There is no need to use cur.fetchone()
when you are already looping over the cursor. Just drop the cur.fetchone()
call and use the row you already fetched with for
:
for row in cur:
for k, v in row.items():
dict_contents[k].append(v)
这篇关于使用sqlite的fetchone()读取循环中的第一行的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!