Entity Framework细节追蹤

为了加深对EF特性的了解so写了一些测试代码测试结果也许对实际项目没什么用处但是对理解EF的相关机制还是有一定帮助的本文可能会不定期更新(加入新的测试用例==)

一事务

直接看代码

所有SaveChange包裹在一个TransactionScope里面

[TestMethod]

public void TestMethod()

{

using (var entities = new SysProcessEntities())

{

using (TransactionScope scope = new TransactionScope())

{

try

{

var test = entitiesSysUserWhere(o => oOrganizationID == )ToList();

var test = entitiesSysRoleToList();

test[]Code = admin;

test[]Name = dddd;

entitiesSaveChanges();

test[]Code = admin;

test[]Name = 全功能;

entitiesSaveChanges();

scopeComplete();

}

catch (Exception e)

{

}

}

}

}

结果

在的基础上去掉TransactionScope

[TestMethod]

public void TestMethod()

{

using (var entities = new SysProcessEntities())

{

var test = entitiesSysUserWhere(o => oOrganizationID == )ToList();

var test = entitiesSysRoleToList();

test[]Code = admin;

test[]Name = dddd;

entitiesSaveChanges();

test[]Code = admin;

test[]Name = 全功能;

entitiesSaveChanges();

}

}

结果

注释掉的第行和第行检查单独的一条语句是否自带事务

[TestMethod]

public void TestMethod()

{ using (var entities = new SysProcessEntities())

{

var test = entitiesSysUserWhere(o => oOrganizationID == )ToList();

var test = entitiesSysRoleToList();

//test[]Code = admin;

test[]Name = dddd;

entitiesSaveChanges();

//test[]Code = admin;

test[]Name = 全功能;

entitiesSaveChanges();

}

}

结果

直接写Sqlupdate [SysProcess][dbo][SysRole] set [name]=全功能 where ID=在查询分析器中执行结果

将改为跨数据库

[TestMethod]

public void TestMethod()

{

using (TransactionScope scope = new TransactionScope())

{

try

{

using (var entities = new SysProcessEntities())

{

var test = entitiesSysUserWhere(o => oOrganizationID == )ToList();

var test = entitiesSysRoleToList();

test[]Code = admin;

test[]Name = dddd;

entitiesSaveChanges();

test[]Code = admin;

test[]Name = 全功能;

entitiesSaveChanges();

}

using (var entities = new DistributionEntities())

{

var test = entitiesVIPCardToList();

test[]Sex = true;

entitiesSaveChanges();

}

scopeComplete();

}

catch (Exception e)

{

string msg = eMessage;

}

}

}

结果

于是整个世界美好了……

二AsNoTracking

注意AsNoTracking要写在最终返回数据的那行代码中才有用看代码

[TestMethod]

public void TestMethod()

{

using (var entities = new SysProcessEntities())

{

var ubs = entitiesUserBrandAsNoTracking();

var obs = entitiesOrganizationBrandWhere(ob => obOrganizationID == )AsNoTracking();

var brands = from ub in ubs

from ob in obs

where ubBrandID == obBrandID

select ubBrandID;

var test = entitiesProBrandWhere(b => brandsContains(bID))ToList();

AssertAreEqual(EntityStateDetached entitiesEntry(test[])State);

}

}

结果

sousing之中应该这么写

var ubs = entitiesUserBrand;

var obs = entitiesOrganizationBrandWhere(ob => obOrganizationID == );

var brands = from ub in ubs from ob in obs where ubBrandID == obBrandID select ubBrandID;

var test = entitiesProBrandWhere(b => brandsContains(bID))AsNoTracking()ToList();

AssertAreEqual(EntityStateDetached entitiesEntry(test[])State);

三DbSetLocal

继续看代码

public void TestMethod()

{

var entities = new SysProcessEntities();

var t = entitiesProBoduanToList();

var t = entitiesProBoduanToList();

AssertAreEqual(t[]t[]);

}

大家以为t[]是否等于t[]?答案是true可是作为引用类型我并没有重载它的Equals方法照理应该为false才对呀修改下测试代码

public void TestMethod()

{

var entities = new SysProcessEntities();

var t = entitiesProBoduanToList();

var t = entitiesProBoduanToList();

string name = t[]Name;

t[]Name = 随便取个名用来测试;

AssertAreEqual(name t[]Name);

}

结果

可知t[]和t[]指向的是同一个对象即t和t指向同一个数组地址也就是entitiesProBoduanLocal指向的地址不过数据库中仍执行了两次取数操作

then加入AsNoTracking试试看

public void TestMethod(){ var entities = new SysProcessEntities();

var t = entitiesProBoduanAsNoTracking()ToList();

var t = entitiesProBoduanAsNoTracking()ToList();

string name = t[]Name; t[]Name = 随便取个名用来测试;

AssertAreEqual(name t[]Name); //truet的更改不影响t表明t和t指向不同地址}

此时entitiesProBoduanLocalCount为

public void TestMethod()

{

var entities = new SysProcessEntities();

var t = entitiesProBoduanFirstOrDefault();

var count = entitiesProBoduanLocalCount;//

var t = entitiesProBoduanToList();

var count = entitiesProBoduanLocalCount;// }

将第行和第行换下位置

public void TestMethod()

{

var entities = new SysProcessEntities();

var t = entitiesProBoduanToList();

var count = entitiesProBoduanLocalCount;//

var t = entitiesProBoduanFirstOrDefault();

var count = entitiesProBoduanLocalCount;//

}

public void TestMethod() {var entities = new SysProcessEntities(); var t = entitiesProBoduanFirstOrDefault();var count = entitiesProBoduanLocalCount;//var t = entitiesProBoduanToList();var count = entitiesProBoduanLocalCount;// }

将第行和第行换下位置

public void TestMethod() {var entities = new SysProcessEntities();var t = entitiesProBoduanToList();var count = entitiesProBoduanLocalCount;// var t = entitiesProBoduanFirstOrDefault();var count = entitiesProBoduanLocalCount;// }

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