Python - 将CSV转换为对象 - 代码设计

Question

我有一个小脚本，用来读取一个包含员工信息的CSV文件，并对这些数据进行一些基本处理。

我们先读取数据（import_gd_dump），然后创建一个Employees对象，这个对象里包含了一系列Employee对象（也许我应该想个更好的命名方式...哈哈）。接着，我们在Employees上调用clean_all_phone_numbers()，这个方法会对每个Employee调用clean_phone_number()，同时也会在Employees上调用lookup_all_supervisors()。

import csv
import re
import sys

#class CSVLoader:
#    """Virtual class to assist with loading in CSV files."""
#    def import_gd_dump(self, input_file='Gp Directory 20100331 original.csv'):
#        gd_extract = csv.DictReader(open(input_file), dialect='excel')
#        employees = []
#        for row in gd_extract:
#            curr_employee = Employee(row)
#            employees.append(curr_employee)
#        return employees
#    #self.employees = {row['dbdirid']:row for row in gd_extract}

# Previously, this was inside a (virtual) class called "CSVLoader".
# However, according to here (http://tomayko.com/writings/the-static-method-thing) - the idiomatic way of doing this in Python is not with a class-function but with a module-level function
def import_gd_dump(input_file='Gp Directory 20100331 original.csv'):
    """Return a list ('employee') of dict objects, taken from a Group Directory CSV file."""
    gd_extract = csv.DictReader(open(input_file), dialect='excel')
    employees = []
    for row in gd_extract:
        employees.append(row)
    return employees

def write_gd_formatted(employees_dict, output_file="gd_formatted.csv"):
    """Read in an Employees() object, and write out each Employee() inside this to a CSV file"""
    gd_output_fieldnames = ('hrid', 'mail', 'givenName', 'sn', 'dbcostcenter', 'dbdirid', 'hrreportsto', 'PHFull', 'PHFull_message', 'SupervisorEmail', 'SupervisorFirstName', 'SupervisorSurname')
    try:
        gd_formatted = csv.DictWriter(open(output_file, 'w', newline=''), fieldnames=gd_output_fieldnames, extrasaction='ignore', dialect='excel')
    except IOError:
        print('Unable to open file, IO error (Is it locked?)')
        sys.exit(1)

    headers = {n:n for n in gd_output_fieldnames}
    gd_formatted.writerow(headers)
    for employee in employees_dict.employee_list:
        # We're using the employee object's inbuilt __dict__ attribute - hmm, is this good practice?
        gd_formatted.writerow(employee.__dict__)

class Employee:
    """An Employee in the system, with employee attributes (name, email, cost-centre etc.)"""
    def __init__(self, employee_attributes):
        """We use the Employee constructor to convert a dictionary into instance attributes."""
        for k, v in employee_attributes.items():
            setattr(self, k, v)

    def clean_phone_number(self):
        """Perform some rudimentary checks and corrections, to make sure numbers are in the right format.
        Numbers should be in the form 0XYYYYYYYY, where X is the area code, and Y is the local number."""
        if self.telephoneNumber is None or self.telephoneNumber == '':
            return '', 'Missing phone number.'
        else:
            standard_format = re.compile(r'^\+(?P<intl_prefix>\d{2})\((?P<area_code>\d)\)(?P<local_first_half>\d{4})-(?P<local_second_half>\d{4})')
            extra_zero = re.compile(r'^\+(?P<intl_prefix>\d{2})\(0(?P<area_code>\d)\)(?P<local_first_half>\d{4})-(?P<local_second_half>\d{4})')
            missing_hyphen = re.compile(r'^\+(?P<intl_prefix>\d{2})\(0(?P<area_code>\d)\)(?P<local_first_half>\d{4})(?P<local_second_half>\d{4})')
            if standard_format.search(self.telephoneNumber):
                result = standard_format.search(self.telephoneNumber)
                return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), ''
            elif extra_zero.search(self.telephoneNumber):
                result = extra_zero.search(self.telephoneNumber)
                return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), 'Extra zero in area code - ask user to remediate. '
            elif missing_hyphen.search(self.telephoneNumber):
                result = missing_hyphen.search(self.telephoneNumber)
                return '0' + result.group('area_code') + result.group('local_first_half') + result.group('local_second_half'), 'Missing hyphen in local component - ask user to remediate. '
            else:
                return '', "Number didn't match recognised format. Original text is: " + self.telephoneNumber

class Employees:
    def __init__(self, import_list):
        self.employee_list = []    
        for employee in import_list:
            self.employee_list.append(Employee(employee))

    def clean_all_phone_numbers(self):
        for employee in self.employee_list:
            #Should we just set this directly in Employee.clean_phone_number() instead?
            employee.PHFull, employee.PHFull_message = employee.clean_phone_number()

    # Hmm, the search is O(n^2) - there's probably a better way of doing this search?
    def lookup_all_supervisors(self):
        for employee in self.employee_list:
            if employee.hrreportsto is not None and employee.hrreportsto != '':
                for supervisor in self.employee_list:
                    if supervisor.hrid == employee.hrreportsto:
                        (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = supervisor.mail, supervisor.givenName, supervisor.sn
                        break
                else:
                    (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = ('Supervisor not found.', 'Supervisor not found.', 'Supervisor not found.')
            else:
                (employee.SupervisorEmail, employee.SupervisorFirstName, employee.SupervisorSurname) = ('Supervisor not set.', 'Supervisor not set.', 'Supervisor not set.')

    #Is thre a more pythonic way of doing this?
    def print_employees(self):
        for employee in self.employee_list:
            print(employee.__dict__)

if __name__ == '__main__':
    db_employees = Employees(import_gd_dump())
    db_employees.clean_all_phone_numbers()
    db_employees.lookup_all_supervisors()
    #db_employees.print_employees()
    write_gd_formatted(db_employees)

首先，我想问的是，从类设计或Python的角度来看，上面的做法有没有什么根本性的问题？逻辑和设计是否合理？

接下来，具体问题如下：

Employees对象有一个方法clean_all_phone_numbers()，它会对里面的每个Employee对象调用clean_phone_number()。这样设计是否不好？如果是，为什么？另外，我调用lookup_all_supervisors()的方式是否也有问题？
最开始，我把clean_phone_number()和lookup_supervisor()这两个方法放在一个函数里，用一个for循环来处理。clean_phone_number的复杂度是O(n)，而lookup_supervisor的复杂度是O(n^2)——这样把它们分成两个循环处理可以吗？
在clean_all_phone_numbers()里，我对Employee对象进行循环，并通过返回值/赋值来设置它们的值——我应该在clean_phone_number()里直接设置这些值吗？

还有一些我觉得有点随意的做法，不知道是否算是坏习惯——比如print_employee()和gd_formatted()都使用了__dict__，而Employee的构造函数用setattr()把字典转换成实例属性。

我很想听听大家的看法。如果你觉得问题太宽泛，请告诉我，我可以把它们拆成几个问题重新发（我只是想避免在论坛上发太多类似的问题，这三个问题其实是紧密相关的）。

谢谢，
Victor

数据处理类设计方法调用复杂度分析实例属性 csv文件编码习惯对象设计

Python - 将CSV转换为对象 - 代码设计

2 个回答

撰写回答