Question

我有班级对象列表＆＃34;数据＆＃34;看起来像：

class Data
{
    int code;
    string name;
    ...
    DateTime date_update;
}

我有另一个班级列表，如：

class RefCodes
{
    int old_code;
    int new_code;
    string new_name;
    DateTime date_update;
}

＆＃34;数据＆＃34;的列表包含1,000个对象。＆＃34; RefCodes＆＃34;的列表包含30个对象。

我需要替换列表＆＃34;数据＆＃34;，田野：＆＃34;代码＆＃34;与＆＃34; new_code＆＃34;的价值一致，和＃34;名称＆＃34;具有＆＃34; new_name＆＃34;。

的值

替换需要仅针对其代码存在于列表中的对象＆＃34; RefCodes＆＃34;。通过查询：如果Data.code == RefCodes.old_code中的代码我该怎么办？

Answer 1

我认为你正在寻找这个：

foreach (var rcodeObj in RefCode)
{
     foreach(var obj in (Data.Where(t => t.code == rcodeObj.old_code)))
     {
        obj.code = rcodeObj.new_code;
        obj.name = rcodeObj.new_name;
     }
}

Answer 2

您可以使用以下代码：

foreach (var x in DataList)
{
    var itemRefCode = RefCodesList.FirstOrDefault(d => d.old_code == x.code);
    if (itemRefCode != null)
    {
        x.code = itemRefCode.new_code;
        x.name = itemRefCode.new_name;
    }
}

Answer 3

如果你使用的是C＃6，你可以使用linq做这样的事情

var updatedData = data.Select(x => new Data
{
   code = refCodes.FirstOrDefault(y => y.old_code == x.code)?.new_code ?? x.code,
   name = refCodes.FirstOrDefault(y => y.old_code == x.code)?.new_name ?? x.name,
});

Answer 4

您可以遍历每个列表并按如下方式更新值。这里我使用了一些示例输入，如下所示。请注意，为简单起见，我正在考虑将这些类的字段公开：

List<Data> dataList = new List<Data>
{
    new Data { code = 1, name = "A" },
    new Data { code = 2, name = "B" },
    new Data { code = 10, name = "C" },
};
List<RefCodes> refList = new List<RefCodes>
{
    new RefCodes { old_code = 1, new_code = 11, new_name = "X" },
    new RefCodes { old_code = 2, new_code = 22, new_name = "Y" }
};

Console.WriteLine("Before");
dataList.ForEach(data => Console.WriteLine(data.code + ": " + data.name));
Console.WriteLine("");

以下是进行更新的代码：

foreach (var refCodes in refList)
{
    foreach (var data in dataList)
    {
        if (data.code == refCodes.old_code)
        {
            data.code = refCodes.new_code;
            data.name = refCodes.new_name;
        }
    }
}
Console.WriteLine("After");
dataList.ForEach(data => Console.WriteLine(data.code + ": " + data.name));

输出：

Before
1: A
2: B
10: C

After
11: X
22: Y
10: C

Answer 5

您需要的是Left Outer Join。例如，

IEnumerable<Data> query = from data in dataList
                          join refCode in refList on data.code equals refCode.old_code into joined
                          from subCode in joined.DefaultIfEmpty()
                          select new Data
                          {
                              code = subCode?.new_code ?? data.code,
                              name = subCode?.new_name ?? data.name,
                              date_update = subCode == null ? data.date_update : DateTime.Now
                          };

将返回一个包含您期望结果的序列。

Answer 6

这会解决您的问题：

    public void Update( List<Data> data, List<RefCodes> refCodes )
    {
        List<RefCodes> differences = refCodes
            .Where( r => data.Any( d => r.old_code == d.code ) )
            .ToList();

        differences.ForEach( ( RefCodes item ) =>
         {
             Data element = data.FirstOrDefault( d => d.code == item.old_code );
             element.code = item.new_code;
             element.name = item.new_name;
         } );
    }

Answer 7

**让我们说tempAllocationR是列表1，而tempAllocationV是List2 **

var tempAllocation = new List<Object>();
    if (tempAllocationR.Count > 0 && tempAllocationV.Count > 0)
                    {
                        foreach (TempAllocation tv in tempAllocationV)
                        {
                            var rec = tempAllocationR.FirstOrDefault(tr => tr.TERR_ID == tv.TERR_ID && tr.TERR == tv.TERR && tr.Team == tv.Team);
                            if (rec != null)
                            {
                                rec.Vyzulta = tv.Vyzulta;
                            }
                            else
                            {
                                tempAllocationR.Add(tv);
                            }

                        }
                        tempAllocation = tempAllocationR;
                    }
                    else if (tempAllocationV.Count == 0 && tempAllocationR.Count > 0)
                    {
                        tempAllocation = tempAllocationR;
                    }
                    else if (tempAllocationR.Count == 0 && tempAllocationV.Count > 0)
                    {
                        tempAllocation = tempAllocationV;
                    }

按另一个列表更新列表（linq）

7 个答案: