Question

为了提供模型及其存储在db中的数据，我想将其写入csv文件。但是，结果csv文件的第一行顺序不正确。

models.py

class BRANCH():
    ID                  =   db.Column(db.String(6), primary_key=True)
    Branch              =   db.Column(db.String(20))
    Status              =   db.Column(db.String(20))
    Curr                =   db.Column(db.String(5))
    Inputter            =   db.Column(db.String(35))
    Createdon           =   db.Column(db.String(20))
    Authorizer          =   db.Column(db.String(35))
    Authorizeon         =   db.Column(db.String(20))
    Description         =   db.Column(db.String(50))
    LocalDescription    =   db.Column(db.String(50))
    BranchManagerName   =   db.Column(db.String(35))
    LocalBranchManagerName = db.Column(db.String(100))
    ContactNumber       =   db.Column(db.String(35))
    Address             =   db.Column(db.String(100))
    LocalAddress        =   db.Column(db.String(100))
    District            =   db.Column(db.String(9))
    Province            =   db.Column(db.String(3))
    ReportLocked        =   db.Column(db.String(1))
    RegisteredDate      =   db.Column(db.String(20))
    PrevMonthAmount     =   db.Column(db.Numeric(25, 9))
    PrevYearAmount      =   db.Column(db.Numeric(25, 9))

因此，db中的数据存储如下：

 Branch | Status | Curr | Inputter  |      Createdon      | Authorizer |     Authorizeon     | ID  |       Description       | BranchManagerName | ContactNumber |                                         Address                                         | District | Province | ReportLocked | RegisteredDate | PrevYearAmount | PrevMonthAmount | LocalBranchManagerName | LocalDescription |                                LocalAddress                                 
--------+--------+------+-----------+---------------------+------------+---------------------+-----+-------------------------+-------------------+---------------+-----------------------------------------------------------------------------------------+----------+----------+--------------+----------------+----------------+-----------------+------------------------+------------------+-----------------------------------------------------------------------------
 HO     | AUTH   | 9    | MINAL | 2018-09-10 21:48:13 | MORAKOT.V  | 2018-09-10 21:48:13 | HO  | Head Office             | Chariya Sambeth   | N/A           | #3722,  Sihanou Blv, Veal Vonging, 7 Makara, Phnom Penh City.                           |          | 12       | 10000        | 2015-12-16     |    0.000000000 |     0.000000000 | ចរិយាសម្បត្តិ              | ការិយាល័យកណ្តាល     | ផ្ទះលេខ៥៧១ ក្រុមទី.៥ ផ្លូវ៥៧៤ ភូមិក. ឃុំ-សង្កាត់វាលវង់ ក្រុង-ស្រុក-ខណ្ឌ៧មករា ខេត្ត-រាជធានីភ្នំពេញ
 HO     | AUTH   | 6    | MINAL | 2018-09-10 21:49:26 | MORAKOT.V  | 2018-09-10 21:49:26 | KPS | Preah Sihanouk Province | Lipop Heang       | N/A           | Group 1110 Village 1112 Commune 1112 Preah Sihanouk Preah Sihanouk                      |          | 18       | 10000        | 2016-07-28     |    0.000000000 |     0.000000000 | ហៀង លីបផប់               | ខែត្រព្រះសីហនុ       | ក្រុម ១១១០ ភូមិ ០២ សង្កាត់ ១១១២ ខណ្ឌព្រះសីហនុ ខេត្តព្រះសីហនុ
 HO     | AUTH   | 2    | MINAL | 2018-09-10 21:50:58 | MORAKOT.V  | 2018-09-10 21:50:58 | SRP | Siemreap Province       | Vicheka Kong      | NA            | House 222A, Street 222A, Knar Village Chreav Commune Siem Reap City Siem Reap Province. | 1710     | 17       | 10000        | 2017-11-24     |    0.000000000 |     0.000000000 | គង់ វិច្ឆការ              | ខែត្រសៀមរាប       | ផ្ទះលេខ២២២អា,<U+200B>ផ្លូវលេខ<U+200B>២២២អា,<U+200B>ភូមិខ្នារ សង្កាត់ជ្រាវ ក្រុងសៀមរាប ខេត្តសៀមរាប

这是我的脚本，用于将这些数据写入csv文件：

from app.Branch.models import *
from sqlalchemy.orm import aliased

TableName = 'BRANCH'

Columns = BRANCH.__table__.columns.keys()

def writeCSV(ID):
    f= open("%s.csv"%TableName,"a+")

    obj = BRANCH.query.order_by(BRANCH.ID).filter(BRANCH.ID==ID).first()

    string = ''

    # set body data
    for col in Columns:
        try:
            string = string + "," + getattr(obj,col).encode('utf-8')
        except Exception as e:
            print col
            string = string + "," + str(getattr(obj,col))

    f.write(string[1:]+'\n')

    f.close

string = ''

f= open("%s.csv"%TableName,"w+")
# set header
for col_header in Columns:
    string = string + "," + col_header
f.write(string[1:]+'\n')
f.close

branchObj = BRANCH.query.all()

for item in branchObj:
    writeCSV(item.ID)

但是，除了如下所示的第一行之外，最终的csv文件还是可以的：

Branch  Status  Curr    Inputter    Createdon   Authorizer  Authorizeon ID  Description LocalDescription    BranchManagerName   LocalBranchManagerName  ContactNumber   Address LocalAddress    District    Province    ReportLocked    RegisteredDate  PrevMonthAmount PrevYearAmount              
 City.  <!> ផ្ទះលេខ៥៧១ ក្រុមទី.៥ ផ្លូវ៥៧៤ ភូមិក. ឃុំ-សង្កាត់វាលវង់ ក្រុង-ស្រុក-ខណ្ឌ៧មករា ខេត្ត-រាជធានីភ្នំពេញ       12  10000   2015-12-16  0   0                                                                   
HO  AUTH    6   MORAKOT.V   2018-09-10 21:49:26 MORAKOT.V   2018-09-10 21:49:26 KPS Preah Sihanouk Province ខែត្រព្រះសីហនុ  Lipop Heang ហៀង លីបផប់  N/A Group 1110 Village 1112 Commune 1112 Preah Sihanouk Preah Sihanouk  ក្រុម ១១១០ ភូមិ ០២ សង្កាត់ ១១១២ ខណ្ឌព្រះសីហនុ ខេត្តព្រះសីហនុ        18  10000   2016-07-28  0   0               
HO  AUTH    2   MORAKOT.V   2018-09-10 21:50:58 MORAKOT.V   2018-09-10 21:50:58 SRP Siemreap Province   ខែត្រសៀមរាប Vicheka Kong    គង់ វិច្ឆការ    NA  House 222A   Street 222A     Knar Village Chreav Commune Siem Reap City Siem Reap Province. ផ្ទះលេខ២២២អា    ផ្លូវលេខ២២២អា ភូមិខ្នារ សង្កាត់ជ្រាវ ក្រុងសៀមរាប ខេត្តសៀមរាប 1710    17  10000   2017-11-24  0   0

数据被截断的位置用<!>标记。

怎么了？我该如何解决？谢谢。

Answer 1

我能够使用模拟数据源在本地重现此内容。

看起来您实际上必须关闭文件以确保已刷新。

f.close()   # instead of f.close

您正在2个地方执行此操作；请注意，f.close返回功能，但是f.close()实际上会调用它。可以使用确定性地重现该问题

def writeCSV(ID):

    f= open("%s.csv"%TableName,"a+")

    obj = BRANCH.query.order_by(BRANCH.ID).filter(BRANCH.ID==ID).first()

    string = ''

    # set body data
    for col in Columns:
        try:
            string = string + "," + getattr(obj,col).encode('utf-8')
        except Exception as e:
            print col
            string = string + "," + str(getattr(obj,col))

    f.write(string[1:]+'\n')
    f.close()
    if ID == 0:
        # here we simulate what would happen if the GC decides
        # to release the first open handle at this point
        g.close()

string = ''

g= open("%s.csv"%TableName,"w+")  # note the rename for demonstration purposes
# set header
for col_header in Columns:
    string = string + "," + col_header
g.write(string[1:]+'\n')
g.close

branchObj = BRANCH.query.all()

for item in branchObj:
    writeCSV(item.ID)

如果不显式调用close，则将其留给GC来决定何时应关闭文件，这可能会导致此类错误。参见http://blog.lerner.co.il/dont-use-python-close-files-answer-depends/

相关说明：考虑一次打开文件，并将f传递到writeCSV中使用，而不是在writeCSV内部打开文件。此外，考虑使用with语法：

with open("%s.csv"%TableName,"w+") as f:
    writeHeader(f)
    for item in branchObj:
        writeCSV(f, item.id)

这样，可以确保您以序列化方式使用一个输出流，并且with会在文件退出后立即将其关闭。

Answer 2

请改用内置CSV模块。这是一个例子。

#!/usr/bin/env python3
import csv

导入inbuilt CSV module。您可以参考文档进行调整。

sample = [("Branch", "Status" ,"Curr"), ("HO","AUTH"), ("HO","AUTH",9)]

类似于您的数据的样本输入。让我们将第一个元组视为标头。

csv.register_dialect(
            'test', 'unix', delimiter=' ', quoting=csv.QUOTE_NONNUMERIC,
            skipinitialspace=True
        )
test_dialect = csv.get_dialect('test')

在这里，我们正在创建一个名为“ test”的自定义方言。我们将分隔符指定为一个空格。

现在让我们打开一个文件并将数据写入其中。在with子句中打开文件将自动关闭它。在这里，我们将创建一个csv.writer对象，即testwriter，将方言作为我们的自定义test_dialect。 testwriter.writerow（）将从元组中写出整行，并以空格作为定界符。

filename = "test.csv"
with open(filename, 'w', newline='') as csvfile:
            testwriter = csv.writer(csvfile, test_dialect)
            for datas in sample:
                testwriter.writerow(datas)

test.csv文件如下，

"Branch" "Status" "Curr"
"HO" "AUTH"
"HO" "AUTH" 9

如何正确写入CSV文件？

2 个答案: