Linq查询将嵌套列表拆分为多个表

本文关键字：拆分 列表 查询 嵌套 Linq | 更新日期: 2023-09-27 18:12:32

我有以下数据结构

List<Items> items = new List<Items>();
    items.Add(new Item() 
    { 
        P1 = "P1",
        P2 = "P2",
        P3 = "P3", 
        P4 = new List<P4> 
        {
            new P4() {T1 = 1, T2 = "test", T3 = 1, T4 = 1},
            new P4() {T1 = 2, T2 = "test", T3 = 2, T4 = 2},
        }
    });
    items.Add(new Item() 
    { 
        P1 = "P11",
        P2 = "P12",
        P3 = "P13", 
        P4 = new List<P4> 
        {
            new P4() {T1 = 3, T2 = "test", T3 = 3, T4 = 1},
            new P4() {T1 = 4, T2 = "test", T3 = 3, T4 = 1},
        }
    });

我有GetData()方法返回上述数据结构/data。

我有三张表

Table 1 columns are: P1, P2, P3 
Table 2 columns are: T1 and T2, (P1 FK)
Table 3 columns are: T3, T4 (T1 FK)

我不知道如何转换/分割我的上述数据结构来存储它进入以上三个表?

我试着

创建一个class.cs

public class DTO
{
  public list<table1> table 1 {get; set;}
}
public class table 1
{
    public string P1 {get; set;}
    public string P2 {get; set;}
    public string P3 {get; set;}
    public list<tabl2> 
}
public class table 2
{
    public string t1 {get; set;}
    public string t2 {get; set;}
    public list<t3>
}
public class table 3
{
    public string t3 {get; set;}
    public string t4 {get; set;}
}
查询

尝试了一些查询，但无法成功

Dto dto = new Dto();
var data = GetData();
foreach(item it in data)
{
 dto.table1.add(new table1
{
  p1 = it.p1,
  p2 = it.p2,
  p3 = it.p3
  t1 // not sure how i populate this since it is expecting list 
})
}

Linq查询将嵌套列表拆分为多个表

未抛光版本。但是像下面这样:

var tables = new List<Table1>();
            foreach (var item in items)
            {
                var t1 = new Table1
                {
                    P1 = item.P1,
                    P2 = item.P2,
                    P3 = item.P3,
                    Table2s = new List<Table2>()
                };
                var p4Group = item.P4s.GroupBy(pt => new {pt.T1, pt.T2 });
                foreach (var p4 in p4Group)
                {
                    var table2 = new Table2
                    {
                        T1 = p4.Key.T1,T2 = p4.Key.T2, Table3s = new List<Table3>()
                    };
                    var p4S = p4.ToList();
                    foreach (var p4FromGroup in p4S)
                    {
                        table2.Table3s.Add(new Table3
                        {
                            T3 = p4FromGroup.T3,
                            T4 = p4FromGroup.T4
                        });
                    }
                    t1.Table2s.Add(table2);
                }
                tables.Add(t1);
            }

我不确定我是否完全理解你的模型但我认为有一种方法可以类似于

List<Table1> itemsTable 1 = 
    items.select(i => new Table1() {
        p1 = i.p1,
        p2 = i.p2,
        p3 = i.p3,
        Table2 = i.p4.select(p4 => MapToTable2(p4)).ToList()
    }).ToList();
private Table2 MapToTable2(P4 p4Items){
    return new Table2() {
        t1 = p4.T1,
        t2 = p4.T2
        Table3 = new Table3() {
            t3 = p4.T3,
            t4 = p4.T4
        }
    };
}
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