比较爽的导航查询功能 .NET ORM / SqlSugar

2022年5月21日13:58:57

.NET ORM 新概念导航

今天这篇文章分享一款好用简单的ORM框架 SqlSugar ，相比 EF Core的导航查询更加简单，配置更加容易，几分钟就能上手

1、导航查询特点

作用：主要处理主对象里面有子对象这种层级关系查询

1.1 无外键开箱就用

其它ORM导航查询需要各种配置或者外键，而SqlSugar则开箱就用，无外键，只需配置特性和主键就能使用

1.2 高性能优

查询性能非常强悍

支持大数据分页导航查询

3.3 语法超级爽

注意：多级查询时VS有时候没提示直接写就行了，相比其他 .NET ORM语法要简单的多

 var list=db.Queryable<Test>()
           .Includes(x => x.Provinces,x=>x.Citys ,x=>x.Street)//多级查询 有时候VS没提示手写 
           .Includes(x => x.ClassInfo)// 一级查询
           .ToList();
                 
                 
 var list=db.Queryable<Test>()
        //多级查询  加排序过滤
        .Includes(x =>x.Provinces.Where(z=>z.Id>0).OrderBy(z=>z.Id).ToList(),x=>x.Citys,x=>x.Street)
         // 一级查询
        .Includes(x =>x.ClassInfo)
        .ToList();

2、新导航查询 ORM

适合有主键的常规操作, 请升级到5.0.6.8

2.1 一对一

//实体publicclass StudentA
        {
            [SugarColumn(IsPrimaryKey=true, IsIdentity = true)]publicint StudentId {get;set; }publicstring Name {get;set; }publicint SchoolId {get;set; }
            [Navigate(NavigateType.OneToOne, nameof(SchoolId))]//一对一public SchoolA SchoolA {get;set; }
  
        }publicclass SchoolA
        {
            [SugarColumn(IsPrimaryKey=true, IsIdentity = true)]publicint SchoolId {get;set; }publicstring SchoolName {get;set; } 
        }//代码var list2 = db.Queryable<StudentA>()
           .Includes(x=> x.SchoolA)
           .Where(x=> x.SchoolA.SchoolName =="北大")//可以对一级导航进行过滤
           .ToList();

2.2 一对多

    public class StudentA
    {
     [SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
     public int StudentId { get; set; }
     public string Name { get; set; }
     public int SchoolId { get; set; }
     [Navigate(NavigateType.OneToMany, nameof(BookA.studenId))]
     public List<BookA> Books { get; set; }
 
     }
    public class BookA
    {
       [SugarColumn(IsPrimaryKey = true, IsIdentity = true)]
       public int BookId { get; set; }
      public string Name { get; set; }
      public int studenId { get; set; }
    }
         
    //例1: 简单用法
    var list = db.Queryable<StudentA>()
    .Includes(x => x.Books)
    .ToList();
     
    //例2:支持Any和Count 对主表进行过滤
    var list = db.Queryable<StudentA>()
    .Includes(x => x.Books)
     .Where(x=>x.Books.Any(z=>z.BookId==1))
    .ToList();
     
    //例3:对子对象进行排序和过滤
     var list = db.Queryable<StudentA>()
       .Includes(x => x.Books.Where(y=>y.BookId >0).OrderBy(y=>y.BookId ).ToList()) 
       .ToList();

2.3 多对多

//多对多publicclass ABMapping1
       {
            [SugarColumn(IsPrimaryKey=true )]publicint AId {get;set; }
            [SugarColumn(IsPrimaryKey=true)]publicint BId {get;set; }
        }publicclass A1
        {
            [SugarColumn(IsPrimaryKey=true, IsIdentity = true  )]publicint Id {get;set; }publicstring Name {get;set; }
            [Navigate(typeof(ABMapping1),nameof(ABMapping1.AId),nameof(ABMapping1.BId))]public List<B1> BList {get;set; }
        }publicclass B1
        {
            [SugarColumn(IsPrimaryKey=true , IsIdentity = true)]publicint Id {get;set; }publicstring Name {get;set; }
            [Navigate(typeof(ABMapping1), nameof(ABMapping1.BId), nameof(ABMapping1.AId))]public List<A1> AList {get;set; }
        }//例1:简单用法var list3= db.Queryable<A1>().Includes(x => x.BList).ToList();//例2:支持子对象排序和过滤var list3= db.Queryable<A1>().Includes(x => x.BList.Where(z=>z.Id>0).ToList()).ToList();//例3:支持主表过滤  Any和Countvar list3= db.Queryable<A1>().Includes(x => x.BList)
                             .Where(x=>x.BList .Any(z=>z.Id ==1)).ToList();

2.4 多级查询

配置好实体类，我们可以多级查询，.NET 中轻松多级查询

 var list=db.Queryable<Test>()
                .Includes(x => x.Provinces,x=>x.Citys ,x=>x.Street)//有时候没提示 直接写
                .Includes(x => x.ClassInfo)// 一级查询
                .ToList();

2.5 大数据分页导航

适合一次性查询1000条以上的导航

  var list = new List<Tree1>();
 
    db.Queryable<Tree1>()
        .Includes(it => it.Child)
        .ForEach(it => list.Add(it), 300); //每次查询300条

更多用法：https://www.donet5.com/Home/Doc?typeId=2414

3、ORM无配置映射（高性能）

适合没有主键或者复杂的一些操作

3.1 无配置映射实现二层

结构: Student->SchoolA

var list = db.Queryable<StudentA>().ToList();
db.ThenMapper(list, stu =>
{
  //如果加Where不能带有stu参数，stu参数写到 SetContext
  stu.SchoolA=db.Queryable<SchoolA>().SetContext(scl=>scl.SchoolId,()=>stu.SchoolId,stu).FirstOrDefault();
});
// SetContext不会生成循环操作，高性能  和直接Where性能是不一样的

如果没有SetContext那么这个查询将会循环

3.2 无配置映射无限级

了解原理后我们用ThenMapper想映射哪层就映射哪层

var treeRoot=db.Queryable<Tree>().Where(it => it.Id == 1).ToList();
//第一层
db.ThenMapper(treeRoot, item =>
{
    item.Child = db.Queryable<Tree>().SetContext(x => x.ParentId, () => item.Id, item).ToList();
});
//第二层
db.ThenMapper(treeRoot.SelectMany(it=>it.Child), it =>
{
    it.Child = db.Queryable<Tree>().SetContext(x => x.ParentId, () => it.Id, it).ToList();
});
//第三层
db.ThenMapper(treeRoot.SelectMany(it => it.Child).SelectMany(it=>it.Child), it =>
{
    it.Child = db.Queryable<Tree>().SetContext(x => x.ParentId, () => it.Id, it).ToList();
});
//这儿只是用树型结构来证明可以实现无限级别导航查询 ,实际开发中树型结构用ToTree实现
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; }
}
// SetContext不会生成循环操作，高性能  和直接Where性能是不一样的

4 、.NET ORM 未来计划

Json to sql 正在开发中，未来将打造一套直接由前端操作数据库的API

 {
 "Queryable":"order",
  Select:[ [{SqlFunc_AggregateMin:["id"]},"id"], [{SqlFunc_GetDate:[]},"Date"] ]
 }

将支持权限过滤，验证，多表查询，层级导航查询等

GitHUB 源码：

https://github.com/donet5/SqlSugar

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