如何从C#中的不同列表合并2个对象? [英] How to merge 2 object from different list in c#?

问题描述

我在c#中有以下两个 Item 对象列表:

I have following 2 list of Item objects in c#:

public class Item
{
    public int Id { get; set; }
    public List<string> Orders { get; set; }
}

List<Item> items1 = new List<Item>() { 
      new Item() { Id = 1, Code = 23, Orders = new List<string>() { "A", "B" }},
      new Item() { Id = 2, Code = 24, Orders = new List<string>() { "C", "D" }}
};

List<Item> items2 = new List<Item>() { 
      new Item() { Id = 1, Code = 23, Orders = new List<string>() { "E", "F" }},
      new Item() { Id = 2, Code = 24, Orders = new List<string>() { "G", "H" }}
};

我想合并ID和代码相同的两个列表中的Item对象，因此以上两个列表的输出应为具有以下条目的单个列表:

I want to merge the Item objects from both lists whose Id and code is same, so the output of above 2 list should be single list with the following entries:

{ 
  new Item() { Id = 1, Code = 23, Orders = new List<string>() { 'A', 'B', 'E', 'F' },
  new Item() { Id = 2, Code = 24, Orders = new List<string>() { 'C', 'D', 'G', 'H' }
};

我如何使用linq在c#中做到这一点?

How can i do this in c# using linq ?

推荐答案

您可以同时加入两个列表，然后加入Union他们的Orders，例如:

You can join both list and then Union their Orders like:

List<Item> combined = (from t in items1
                       join r in items2 on new { t.Id, t.Code } equals new { r.Id, r.Code }
                       select new Item
                       {
                           Id = t.Id,
                           Code = t.Code,
                           Orders = t.Orders.Union(r.Orders).ToList()

                       }).ToList();

您将获得:

如果需要连接Orders，则可以将Union替换为Concat.因此，如果您的订单包含"A"，"B"和"A"，"F"，那么使用concat您将获得"A","B,"A","F"，而使用Union您将获得"A", "B", "F"

If you need your Orders to be concatenated then you can replace Union with Concat. So if your order contains "A", "B" and "A", "F", then with concat you will get "A","B,"A","F" and with Union you will get "A", "B", "F"

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