使用存儲在字典中的字符串調用類

Question

我帶回了十多種Scrapy項目類型，將它們全部清理並存儲在SQL中的各個表中。我可以爲每個項目寫出說明，但看​​起來更加整潔，以編程方式管理各種列表/數據框/表格創建。

• 不幸的是，當我嘗試通過引用字典中的條目來調用scrapy項目時，Python將其讀取爲字符串而不是類型或類。
• 同樣，當我嘗試引用一個列表名 - Python仍然看到一個字符串不會讓我使用.append（）。

任何獲得Python讀取字符串作爲類引用或列表引用的幫助將不勝感激。

這裏是我的代碼版本：

from scrapy import signals 
from dealinfo.items import List, Details, Rd, Status, CompletedDetails, Syndicate 
from dealinfo.items import CompanyDetails, CompanyContactInfo, CompanyTeam, Compadvisors, CompanyPInvestors 
from dealinfo.items import CompanyExecSum, CurrentRd, PastRd, AnnFin#, CompanyDocs 

import pandas as pd 
from sqlalchemy import create_engine 

class SQLPipeline(object): 
    engine=create_engine('mssql+pyodbc://username:password@database') 

    #### matrix of table names by type ###### 
    prep = {'item_names': ['List', 'Details', 'Rd', 'Fin', 'Status', 'CompletedDetails', 'Syndicate', 'CompanyDetails', 'CompanyContactInfo', 'CompanyTeam', 'Compadvisors', 'CompanyPInvestors', 'CompanyExecSum', 'CompanyCurrentRd', 'CompanyPastRd', 'CompannFin', 'CompanyDocs'], 
      'temp_table': ['items_dl', 'items_dd', 'items_dr', 'items_df', 'items_nds', 'items_ncd', 'items_ns', 'items_cd', 'items_cci', 'items_ct', 'items_ca', 'items_cpi', 'items_es', 'items_cr', 'items_pr', 'items_af', 'items_cdoc'],    
      'data_frame': ['dl', 'dd', 'dr', 'df', 'nds', 'ncd', 'ns', 'cd', 'cci', 'ct', 'ca', 'cpi', 'es', 'cr', 'pr', 'af', 'cdoc'], 
      'sql_table': ['list', 'details', 'rd', 'fin', 'status', 'completed_details', 'syndicate', 'company_details', 'company_contact_info', 'company_team', 'company_advisors', 'company_pinvestors', 'company_execsum', 'company_current_rd', 'company_past_rd', 'company_ann_fin', 'company_docs'] 
      } 

    #### assigning temporary lists for capturing parsed items ###### 
    for x in prep['temp_table']: 
     globals()[x] = [] 

    #### create sql schema to receive final output ###### 
    def __init__(self): 
     try: ## Check schema exists, create if not 
      SQLPipeline.engine.execute("create schema dealinfo") 
     except: 
      pass 

    #### clean each scrapy item and add contents to temporary list (ahead of conversion to dataframe) ###### 
    def process_item(self, item, spider): 
     for i in range(len(SQLPipeline.prep['item_names'])): 
      if isinstance(item, SQLPipeline.prep['item_names'][i]):####<<---error - not able to call item using string 
       for key,value in item.items(): 
        if isinstance(item[key], list): 
         item[key] = [x.strip() for x in item[key] if x] 
         item[key] = [x for x in item[key] if x] 
         item[key] = ', '.join(item[key]) 
       SQLPipeline.prep['temp_table'][i].append(item.copy())####<<---error - not able to call item using string 

    #### convert parsed items to pandas dataframe before sending to sql as tables ######  
    def close_spider(self, spider): 
     for i in SQLPipeline.prep['item_names']: 
      try: 
       SQLPipeline.prep['data_frame'][i] = pd.DataFrame(SQLPipeline.prep['temp_table'][i]) 
       print(SQLPipeline.prep['data_frame'][i]) 
       SQLPipeline.prep['data_frame'][i].to_sql(SQLPipeline.prep['sql_table'][i], SQLPipeline.engine, schema='dealinfo', if_exists='replace', index=False) 
      except Exception as ex: 
       print(ex) 
       pass 

Answer 1

juanpa.arrivillaga了我的情況正確的答案 - 固定的這一切 - 現在一切都運行。我向列表頂部聲明瞭一個列表，然後將列表和項目添加到我的字典中。不需要任何東西！

for x in ['items_dl','items_dd','items_dr','items_df','items_nds','items_ncd','items_ns','items_cd','items_cci','items_ct','items_ca','items_cpi','items_es','items_cr','items_pr','items_af','items_cdoc']: 
    globals()[x] = [] 
    prep = {'temp_table': [items_dl, items_dd, items_dr, items_df, items_nds, items_ncd, items_ns, items_cd, items_cci, items_ct, items_ca, items_cpi, items_es, items_cr, items_pr, items_af, items_cdoc], 
     'item_names': [List, Details, Rd, Status, CompletedDetails, Syndicate, CompanyDetails, CompanyContactInfo, CompanyTeam, Compadvisors, CompanyPInvestors, CompanyExecSum, CompanyCurrentRd, CompanyPastRd, CompannFin, CompanyDocs], 
     'data_frame': ['dl', 'dd', 'dr', 'df', 'nds', 'ncd', 'ns', 'cd', 'cci', 'ct', 'ca', 'cpi', 'es', 'cr', 'pr', 'af', 'cdoc'], 
     'sql_table': ['list', 'details', 'rd', 'fin', 'status', 'completed_details', 'syndicate', 'company_details', 'company_contact_info', 'company_team', 'company_advisors', 'company_pinvestors', 'company_execsum', 'company_current_rd', 'company_past_rd', 'company_ann_fin', 'company_docs'] 
     } 

Answer 2

我想eval可能會幫助你。

>>> class MyClass(): 
...  pass 
... 
>>> myinstance = Myclass() 

>>> type(myinstance) 
<class '__main__.Myclass'> 

>>> type('myinstance') 
<class 'str'> 

>>> type(eval('myinstance')) 
<class '__main__.Myclass'> 

Answer 3

我相信你正在尋找的是getattr()