處理Django模型

Question

我想從我的模型TradeOrder的數據庫處理查詢：

class TradeOrder(models.Model): 
    #denoted in 2 three letter tickers with underscore such as anc_btc 
    pair = models.CharField(max_length=50) 
    #buy_order or sell_order 
    order_type = models.CharField(max_length=50) 
    #number e.g. .3455 or .190 
    trade_rate = models.PositiveIntegerField() 
    trade_amount = models.PositiveIntegerField() 
    #name of the account 
    trade_order_account = models.CharField(max_length=50) 

    def __str__(self): 
     return '%s %s %s %s %s' % (self.pair, self.order_type, self.trade_rate, self.trade_amount, self.trade_order_account) 

當我下views.py執行我的應用程序

buyorders=TradeOrder.objects.filter(pair="anc_btc", order_type="buy_order") 

我得到看起來名單像這樣：

[<TradeOrder: anc_btc buy_order 7987 7897 a>, <TradeOrder: anc_btc buy_order 7897 789 a>, <TradeOrder: anc_btc buy_order 7897 789 a>] 

所以想要處理和優化數據，首先比較每個項目到一個新的訂單

類似：

  if new_order_type=="buy_order": 
       #crosscheck against sell orders 
       market_sell_orders = TradeOrder.objects.filter(pair="anc_btc", order_type="sell_order", trade_order_account=price) 
       #now i need to sort the orders for trade rates above/greater than $new_order_price 
       #how do i do this? 

我現在知道，這可以通過添加.order_by('trade_order_price') 到查詢年底完成

   if potential_sell_orders is not None: 
       #trade 
        do=1 
       else: 
        #no sell orders to fill, submit to order book 
        try: 
         tradeordersubmit=TradeOrder(pair=order_pair, order_type=order_type, trade_rate=price, trade_amount=quantity, trade_order_account=request.user.username) 
         tradeordersubmit.save() 
         order_error=0 
        except: 
         order_error="1" 

Answer 1

now i need to sort the orders for trade rates above/greater than $new_order_price 

你應該細化適當地使用查詢集的查詢集方法：

market_sell_orders = TradeOrder.objects.filter(pair="anc_btc", order_type="sell_order", trade_order_account=price, trade_rate__gt=<trade_rate>).order_by('-trade_rate') 

你可以找到QuerySet的教程here