django tastypie獲取相關列的總金額

Question

鑑於tastypie下面的JSON結果，我想在check.payments_total上創建一個新值，該值等於付款總額（在本例中爲44.00）。有關如何做到這一點的任何線索？我完全被難住了。支付是檢查表的連接外鍵。

{ 
"objects": [ 
    { 
     "check": { 
      "id": "58a81b36-1ea6-403b-9902-a50cbd13cf2e", 
      "number": 2, 
      "payments": [ 
       { 
        "amount": "5.00", 
       }, 
       { 
        "amount": "39.00", 
       } 
      ] 
     } 
    } 
] 
} 

Answer 1

如果響應，那麼你可以在你的資源覆蓋以下方法（片段是從tastypie.resources.Resource）：

def alter_list_data_to_serialize(self, request, data): 
    """ 
    A hook to alter list data just before it gets serialized & sent to the user. 

    Useful for restructuring/renaming aspects of the what's going to be 
    sent. 

    Should accommodate for a list of objects, generally also including 
    meta data. 
    """ 
    return data 

只包括像（未測試，認爲是僞代碼）：

total_amount = 0.0 
for object in data[ 'objects' ]: 
    total_amount += object[ 'amount' ] 

return { 'objects' : data[ 'objects' ], 'total_amount' : total_amount } 

你應該完成。