C# 用于返回具有多个子数组的对象列表的Linq查询

传入列表

    var list = new List<Franchise>()
    {
     new Franchise()
     {Id = 10, Name = "Franchise1", Code= "DD1", IsDomestic= 1, ParentCompanyId=1, GroupId=100 },        
     new Franchise()
     {Id = 10, Name = "Franchise1", Code= "DD1", IsDomestic= 1, ParentCompanyId=2, GroupId=100 },
     new Franchise()
     {Id = 10, Name = "Franchise1", Code= "DD1", IsDomestic= 1, ParentCompanyId=3, GroupId=200 },
     new Franchise()
     {Id = 15, Name = "Franchise5", Code= "FD1", IsDomestic= 0, ParentCompanyId=4, GroupId=300 },
     new Franchise()
     {Id = 15, Name = "Franchise5", Code= "FD1", IsDomestic= 0, ParentCompanyId=3, GroupId=300 },
     new Franchise()
     {Id = 15, Name = "Franchise5", Code= "FD1", IsDomestic= 0, ParentCompanyId=2, GroupId=400 },
   };

输出-阵列中包含ParentCompanyID和GroupID的每个特许经营权一行

    var list = new List<Franchise>()
    {
       new Franchise()
       {Id = 10, Name = "Franchise1", Code= "DD1", IsDomestic= 1, ParentCompanyIds=[1, 2, 3], GroupIds = [100, 200 ]},        
       new Franchise()
       {Id = 15, Name = "Franchise2", Code= "FD1", IsDomestic= 0, ParentCompanyIds=[4, 3, 2], GroupIds = [300, 400] }
    };

var list=新列表（）
{
新专营权（）
{Id=10，Name=“特许经营1”，Code=“DD1”，IsDomestic=1，ParentCompanyIds=[1,2,3]，GroupIds=[100200]}，
新专营权（）
{Id=15，Name=“特许经营2”，Code=“FD1”，IsDomestic=0，ParentCompanyIds=[4,3,2]，GroupIds=[300400]}
};

实现这一点的高效LINQ查询是什么？提前谢谢

---

您可以尝试以下方法：

var collectionGroup = list.GroupBy(x => new { x.Name, x.Id, x.Code, x.IsDomestic }).ToList();
var result = collectionGroup.Select(x => new FranchiseNew
        {
            Id = x.Key.Id,
            Name = x.Key.Name,
            Code = x.Key.Code,
            IsDomestic = x.Key.IsDomestic,
            CategoryIds = x.GroupBy(s => s.ParentCompanyId).Select(y => y.Key).ToArray(),
            DivisionIds = x.GroupBy(s => s.GroupId).Select(y => y.Key).ToArray()
        }).ToList();

---

在新模型中，添加代码字段

您不需要通过

.ToList

实现

collectionGroup

。使用

GroupBy

来选择不同的ID是过分的，请使用

.select（s=>s.GroupId）.distinct（）

感谢sri harsha和Guru Stron。上述解决方案有效。但在我的问题上，当我拥有特许经营权的时候。我没有特许经营类，数据来自数据表。当我尝试在x.GroupBy（s=>s.GroupId）上使用相同的方法时，我得到一个错误“表示一个对象，其操作将在运行时得到解决”。感谢Sri harsha nad Guru Stron。这个解决方案有效。

var collectionGroup = list.GroupBy(x => new { x.Name, x.Id, x.Code, x.IsDomestic }).ToList();
var result = collectionGroup.Select(x => new FranchiseNew
        {
            Id = x.Key.Id,
            Name = x.Key.Name,
            Code = x.Key.Code,
            IsDomestic = x.Key.IsDomestic,
            CategoryIds = x.GroupBy(s => s.ParentCompanyId).Select(y => y.Key).ToArray(),
            DivisionIds = x.GroupBy(s => s.GroupId).Select(y => y.Key).ToArray()
        }).ToList();