在函數中使用字符串作爲參數

Question

我試圖在函數中使用字符串作爲參數。是這樣的可能嗎？

from django.contrib.auth.models import User 

param_var = 'contains' 
User.objects.filter(first_name__{param_var}='John') 

# ideally, this should equate to: 
User.objects.filter(first_name__contains='John') 

Answer 1

param_var = 'contains' 
User.objects.filter(**{'first_name__%s'%param_var: 'John'}) 

雖然我真的想知道這樣做的智慧......我想你可能會被重新發明的SQL注入...

我懷疑有一個更好的辦法。你應該更多地解釋你正在努力完成的事情。

Answer 2

解決：

# Something like this... 
qs = User.objects.all() 

parameters = { 
    'name': { 
     'type': 'get', 
     'filter': [ 
      'first_name__icontains', 
      'last_name__icontains', 
      # ... 
     ], 
    }, 
    # ... 
} 

for parameter, data in parameters.items(): 
    if data['type'] == 'get': 
     value = request.GET.get(parameter, None) 
    elif data['type'] == 'getlist': 
     value = request.GET.getlist(parameter) 

    if value: 
     query = Q() 

     for f in data['filter']: 
      query = query | Q(**{ f : value }) 
     qs = qs.filter(query)