EntityFramework中几种操作小结

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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。

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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; }
????}

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查询中加入RowVersion比较

1. 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");
????????}
????}

1. 用扩展函数查询

????db.Products.Where(i => i.RowVersion.Compare(version) > 0).ToList();

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乐观锁

????public class Product
????{
????????public int Id { get; set; }
????????public string Name { get; set; }

????????[Timestamp, ConcurrencyCheck]
????????public Byte[] RowVersion { get; set; }
????}

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带过滤条件的DBSet

1. 添加Can a DbContext enforce a filter policy?一文中的FilteredDbSet，
2. 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); } }

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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;
????????}
????}

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单元测试：

1. 打桩DbSet：FakeDbSet
2. DbContext的封装

EntityFramework中几种操作小结

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原文地址：http://www.cnblogs.com/TianFang/p/4439215.html