Add ISugarQueryable<T> Mapper<TObject>(Expression<Func<T, TObject>> mapperObject, Expression<Func<T, object>> mainField, Expression<Func<T, object>> childField);

Src/Asp.Net/SqlServerTest/Demo/Demo1_Queryable.cs

@@ -15,6 +15,32 @@ namespace OrmTest
             JoinTable();
             Async();
             NoEntity();
+            Mapper();
+        }
+
+        private static void Mapper()
+        {
+            Console.WriteLine("");
+            Console.WriteLine("#### Mapper Start ####");
+            var db = GetInstance();
+            //Creater Table
+            db.CodeFirst.InitTables(typeof(Tree));
+            db.DbMaintenance.TruncateTable("tree");
+            db.Insertable(new Tree() { Id = 1, Name = "root" }).ExecuteCommand();
+            db.Insertable(new Tree() { Id = 11, Name = "child1",ParentId=1 }).ExecuteCommand();
+            db.Insertable(new Tree() { Id = 12, Name = "child2",ParentId=1 }).ExecuteCommand();
+            db.Insertable(new Tree() { Id = 2, Name = "root" }).ExecuteCommand();
+            db.Insertable(new Tree() { Id = 22, Name = "child3", ParentId = 2 }).ExecuteCommand();
+
+            var list=db.Queryable<Tree>()
+                                     //parent=(select * from parent where id=it.parent)
+                                     .Mapper(it=>it.Parent,it=>it.ParentId, it=>it.Parent.Id)
+                                     //Child=(select * from parent where ParentId=it.id)
+                                     .Mapper(it => it.Child, it => it.Id, it => it.Parent.ParentId)
+                                     .ToList();
+
+
+            Console.WriteLine("#### End Start ####");
         }
 
         private static void NoEntity()

Src/Asp.Net/SqlServerTest/Models/Mappers.cs

@@ -0,0 +1,20 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace OrmTest
+{
+    public class Tree
+    {
+        [SqlSugar.SugarColumn(IsPrimaryKey =true)]
+        public int Id { get; set; }
+        public string Name { get; set; }
+        public int ParentId { get; set; }
+        [SqlSugar.SugarColumn(IsIgnore = true)]
+        public Tree Parent { get; set; }
+        [SqlSugar.SugarColumn(IsIgnore = true)]
+        public List<Tree> Child { get; set; }
+    }
+}

Src/Asp.Net/SqlServerTest/SqlServerTest.csproj

@@ -56,6 +56,7 @@
     <Compile Include="Demo\DemoD_DbFirst.cs" />
     <Compile Include="Demo\DemoE_CodeFirst.cs" />
     <Compile Include="Models\Custom.cs" />
+    <Compile Include="Models\Mappers.cs" />
     <Compile Include="Models\MyCustomAttributeTable.cs" />
     <Compile Include="Models\Order.cs" />
     <Compile Include="Models\OrderItem.cs" />