目前项目中使用到的EntityFramework中几种操作小结,先标记下。没有详细介绍,后续有空的话再补充一些并完善一下。
列中加入RowVersion时间戳
public class Product
{
public
int Id { get; set; }
public
string Name { get; set; }
[Timestamp]
public
Byte[] RowVersion { get; set; }
}
查询中加入RowVersion比较
- 编写扩展函数
internal
static
class
EntityFrameworkHelper
{
public
static
int Compare(this
byte[] b1, byte[] b2)
{
throw
new
NotImplementedException("This is only for linq to sql");
}
}
- 用扩展函数查询
db.Products.Where(i => i.RowVersion.Compare(version) > 0).ToList();
乐观锁
public
class
Product
{
public
int Id { get; set; }
public
string Name { get; set; }
[Timestamp, ConcurrencyCheck]
public
Byte[] RowVersion { get; set; }
}
带过滤条件的DBSet
- 添加Can a DbContext enforce a filter policy?一文中的FilteredDbSet,
- 修改DbContext,使用FilteredDbSet替换默认的DbSet
public
IDbSet<Product> Products { get { return
new
FilteredDbSet<Product>(this, i=>i.IsRemoved == false); } }
标记删除
继承FilteredDbSet,重载其删除函数
public
interface
IflagRemoveObject
{
bool IsRemoved { get; set; }
}
class
FlagRemoveDbSet<T> : FilteredDbSet<T> where
T : class, IflagRemoveObject
{
public
override
T Remove(T entity)
{
entity.IsRemoved = true;
return entity;
}
}
单元测试:
- 打桩DbSet:FakeDbSet
- DbContext的封装