查询产品中的独占使用实体

Question

我加入了三个列表：Products、AcceptedOffers和Deliverys。

List<Product> products = new List<Product>() {
    new Product(){ Id = 1, Name = "Drink" }
};

List<AcceptedOffer> accepted = new List<AcceptedOffer>() {
    new AcceptedOffer(){ Id = 10, ProductId = 1  },
    new AcceptedOffer(){ Id = 11, ProductId = 1  }
};

List<Delivery> deliveries = new List<Delivery>() {
    new Delivery(){ Id = 101, ProductId = 1, Status = "Success" },
    new Delivery(){ Id = 102, ProductId = 1, Status = "Failure"}
};

我希望将交付与已接受的报价联系起来，但我无法找到一种方法来查询每个AcceptedOffer/交付的独家用途：

var test = from d in deliveries
           join p in products on d.ProductId equals p.Id
           join ao in accepted on p.Id equals ao.ProductId
           select new { d, p, ao };

这意味着：

Drink | 10 | Success
Drink | 11 | Success
Drink | 10 | Failure
Drink | 11 | Failure

如果我按接受的报价分组，那么FirstOrDefault()两次交付都成功；按交付分组，第一个AcceptedOffer相同。

我需要：

Drink | 10 | Success
Drink | 11 | Failure

什么是数学/查询巫毒，使我独家使用每一方？

Answer 1

从技术上讲，您可以尝试Linq SelectMany和Zip来实现压缩(即加入Nth报价和Nth交付)：

Accepted Offer            ->  Delivery
----------------------------------------------------------------------------
{ Id = 10, ProductId = 1} -> { Id = 101, ProductId = 1, Status = "Success" } 
{ Id = 11, ProductId = 1} -> { Id = 102, ProductId = 1, Status = "Failure" }
 ...
 N-th offer               -> N-th delivery

代码：

   var result = products // for each product                              
     .SelectMany(prod => deliveries             
         // we get corresponding deliveries
        .Where(del => del.ProductId = prod.Id)  
         // which we mechanically zip with filtered accepted offeres
        .Zip(accepted.Where(acc => acc.ProductId = prod.Id), 
           (del, acc) => new {
             d  = del.Status,
             p  = prod.Id,   
             ao = acc.Id,
         }));