Python 使用反射實(shí)現(xiàn) Excel 與對(duì)象之間的轉(zhuǎn)換

作者：萬(wàn)百入年許老

來(lái)源：SegmentFault 社區(qū)

場(chǎng)景

需要從Excel中加載到內(nèi)存中，轉(zhuǎn)換為class對(duì)象執(zhí)行操作

環(huán)境

• Python3.8
• openpyxl==3.0.5

前置知識(shí)

反射(僅介紹這個(gè)幫助類用到的幾個(gè)反射方法)

setattr、getattr

class Person():    name = None
    def __init__(self, name):        self.name = name

p = Person("laowang")n = getattr(p, "name")print(n)# 打印結(jié)果：laowang
setattr(p, "name", "laoxu")n2 = getattr(p, "name")print(n2)# 打印結(jié)果：laoxu

反射實(shí)例化對(duì)象

class?Person():    name = None
    def print_sth(self):        print("測(cè)試實(shí)例化方法", self.name)

def test(clazz):    """    實(shí)例化對(duì)象    :param clazz: 要實(shí)例化的類型     """    x = clazz()    setattr(x, "name", "老王")    x.print_sth()    # 打印：測(cè)試實(shí)例化方法 老王test(Person)

Excel操作類庫(kù) - openpyxl

創(chuàng)建Excel

from openpyxl import Workbook

wb = Workbook()ws1 = wb.active
ws1.append(['name', 'age', 'isManager', 'remark'])ws1.append(['', '', '', ' '])ws1.append(['老王', '18', 'false', '  '])ws1.append(['laoxu', '28.4', 'TRUE', 'zaoricaifuziyou'])ws1.append(['', '', '', ' '])
ws2 = wb.create_sheet("ws2")
ws2.append(['name', 'age', 'isManager', 'remark'])ws2.append(['小李', '50', 'TRuE', 'fly knife'])ws2.append(['', '', '', ' '])ws2.append(['aaa', '11', 'false', 'hehehe'])
wb.save("test_convert_2_class.xlsx")

讀取Excel

from openpyxl import Workbook
def print_row(arr):    """為了顯示方便，打印行"""    for item in arr:        print(item,end="\t\t|")    print()
# 讀取上一個(gè)代碼塊創(chuàng)建的Excel代碼work_book = load_workbook("test_convert_2_class.xlsx")result = []for sheet_name in work_book.sheetnames:    print("-----------------",sheet_name,"-----------------")    ws = work_book[sheet_name]
    # 獲取表頭    table_heads = []    for title_row in ws.iter_rows(max_row=1):        for cell in title_row:            table_heads.append(cell.value)    print_row(table_heads)    # 獲取表數(shù)據(jù)    table = []    for row in ws.iter_rows(min_row=2):        row_data=[]        for column_index in range(len(row)):            row_data.append(row[column_index].value)        print_row(row_data)# 打印結(jié)果如下：# ----------------- Sheet -----------------# name        |age        |isManager        |remark        |# None        |None        |None        |         |# 老王        |18        |false        |          |# laoxu        |28.4        |TRUE        |zaoricaifuziyou        |# None        |None        |None        |         |# ----------------- ws2 -----------------# name        |age        |isManager        |remark        |# 小李        |50        |TRuE        |fly knife        |# None        |None        |None        |         |# aaa        |11        |false        |hehehe        |

伸手黨代碼

excel_helper.py

import osimport refrom os.path import isfile
from openpyxl import load_workbook, Workbook

def _convert_value(value):    """    將單元格中數(shù)據(jù)，區(qū)分基本類型    類似"true"/"false"(不區(qū)分大小寫(xiě))轉(zhuǎn)換為bool值    長(zhǎng)得像數(shù)字的轉(zhuǎn)換為float類型    其他（空格、空行）轉(zhuǎn)換為None    :param value: 單元格的值    :return: 轉(zhuǎn)換后的類型    """    value_str = str(value).lower()    if value_str == 'true':        return True    elif value_str == 'false':        return False    elif re.match(r"^[+|-]?\d+.?\d*$", value_str):        return float(value_str)    elif re.match(r"^\s*$", value_str):        return None    else:        return value

class ExcelHelper:    """    Excel幫助類    """
    @classmethod    def convert_2_class(cls, file_path, clazz):        """        轉(zhuǎn)換為class，可轉(zhuǎn)換多張sheet表，轉(zhuǎn)換為統(tǒng)一clazz對(duì)象        過(guò)濾掉為空行        :param file_path:Excel文件路徑        :param clazz:結(jié)果轉(zhuǎn)換為clazz對(duì)象        :return: 對(duì)象列表的列表，結(jié)構(gòu)為[[clazz(),clazz()],[clazz()]]        """        if not file_path.endswith(".xlsx"):            raise ValueError("文件必須為.xlsx結(jié)尾的Excel文件")        if not isfile(file_path):            raise FileNotFoundError("文件路徑 {0} 不存在".format(file_path))        work_book = load_workbook(file_path)        result = []        for sheet_name in work_book.sheetnames:            ws = work_book[sheet_name]
            # 獲取表頭            table_heads = []            for title_row in ws.iter_rows(max_row=1):                for cell in title_row:                    table_heads.append(cell.value)            # 獲取表數(shù)據(jù)            table = []            for row in ws.iter_rows(min_row=2):                # 實(shí)例化對(duì)象                instance = clazz()                for column_index in range(len(row)):                    setattr(instance, table_heads[column_index], _convert_value(row[column_index].value))
                # 過(guò)濾空行（所有屬性均為None的對(duì)象）                is_valid = False                for attr in instance.__dict__:                    if not attr.startswith("_") and instance.__dict__[attr] is not None:                        is_valid = True                        break                if is_valid:                    table.append(instance)            result.append(table)        return result
    @classmethod    def save(cls, file_path, tables):        if not file_path.endswith(".xlsx"):            raise ValueError("文件必須為.xlsx結(jié)尾的Excel文件")        work_book = Workbook()        is_first = True        for table in tables:            if is_first:                ws = work_book.active                is_first = False            else:                ws = work_book.create_sheet()            # 添加表頭            table_heads = []            for attr in table[0].__dict__:                # 過(guò)濾"_"開(kāi)頭的屬性                if not attr.startswith("_"):                    table_heads.append(attr)            ws.append(table_heads)
            # 添加數(shù)據(jù)            for row in table:                data = []                for head in table_heads:                    data.append(getattr(row, head))                ws.append(data)        try:            # 生成保存文件夾路徑            folder_index = max(file_path.rfind("\\"), file_path.rfind("/"))            if folder_index != -1:                folder_path = file_path[0:folder_index]                if not os.path.exists(folder_path):                    os.mkdir(folder_path)            work_book.save(file_path)        except Exception:            raise OSError("創(chuàng)建Excel失敗")

使用方法

# 導(dǎo)入類from excel_helper import ExcelHelper
# 示例對(duì)象class A:    name=None    age=None    isManager=None
# 讀取Excel文件，并轉(zhuǎn)換為指定類型對(duì)象列表tables = ExcelHelper.convert_2_class("123.xlsx", A)
# 保存為Excela1=A()table=[a1]ExcelHelper.save("456.xls", [table])

注意

• 該幫助類均為@classmethod
• 該幫助類使用反射實(shí)現(xiàn)，所以表頭名稱需要與對(duì)象的字段名一一對(duì)應(yīng)（如代碼中的class A 與 下表"表1-1"）
• Excel中可以有多張表（sheet tab），所以參數(shù)為對(duì)象列表的列表，請(qǐng)注意對(duì)應(yīng)關(guān)系
• 當(dāng)前讀取Excel僅能轉(zhuǎn)換為一個(gè)class類型，所以多種表結(jié)構(gòu)請(qǐng)使用多張表

表1-1

參考資料

PYTHON里的反射(自學(xué)習(xí))：https://www.cnblogs.com/kongk/p/8645202.html

以上