概念
ISoftDelete即软删除，数据在进行delete后不会从数据库清除，而只是标记一个状态，在业务范围里都不能获取到这个数据，这在ORM框架里还是比较容易实现的，对传统的ado来说需要对sql统一进行拦截和条件过滤．
实施步骤
- 实体继承ISoftDelete
- 数据上下文实现对IsDeleted的过滤
- 对删除方法进行调整，添加对ISoftDelete的支持
代码实现
1 实体继承ISoftDelete
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
foreach (var entityType in modelBuilder.Model.GetEntityTypes())
{
// 1. Add the IsDeleted property
entityType.GetOrAddProperty("IsDeleted", typeof(bool)); // 2. Create the query filter
var parameter = Expression.Parameter(entityType.ClrType); // 3. EF.Property<bool>(post, "IsDeleted")
var propertyMethodInfo = typeof(EF).GetMethod("Property").MakeGenericMethod(typeof(bool));
var isDeletedProperty = Expression.Call(propertyMethodInfo, parameter, Expression.Constant("IsDeleted")); // 4. EF.Property<bool>(post, "IsDeleted") == false
BinaryExpression compareExpression = Expression.MakeBinary(ExpressionType.Equal, isDeletedProperty, Expression.Constant(false)); // 5. post => EF.Property<bool>(post, "IsDeleted") == false
var lambda = Expression.Lambda(compareExpression, parameter); modelBuilder.Entity(entityType.ClrType).HasQueryFilter(lambda);
2 数据上下文实现对IsDeleted的过滤
public class ProductInfo : EntityBase, ISoftDelete
{
public string Title { get; set; }
public decimal Amount { get; set; }
public int Discount { get; set; }
public int Inventory { get; set; }
public DateTime DeletedDate { get; set; }
public string DeletedUser { get; set; }
public bool IsDeleted { get; set; } /// <summary>
/// domain method
/// </summary>
/// <returns></returns>
public decimal GetSaleAmount()
{
return Amount * Discount / ;
}
}
3 对删除方法进行调整，添加对ISoftDelete的支持
代码来自Lind.DotNetCore.Repository.EFRepository类型
public void Delete(TEntity item)
{
if (item != null)
{
if (typeof(ISoftDelete).IsAssignableFrom(item.GetType()))
{
Db.Entry(item).State = EntityState.Modified;
var delEntity = item as ISoftDelete;
delEntity.DeletedDate = DateTime.Now;
delEntity.IsDeleted = true;
}
else
{
//物理删除
Db.Set<TEntity>().Attach(item as TEntity);
Db.Entry(item).State = EntityState.Deleted;
Db.Set<TEntity>().Remove(item as TEntity);
}
this.SaveChanges();
}
}
上面几行代码实现了对软删除的完整支持，从ISoftDelete接口到数据上下文里的过滤IsDeleted，再到优化后的Delete()方法，一切看上去都很优雅！
对于软删除支持的框架也很多，像abp,eshopconationer,linddotnetcore等！
欢迎大家的阅读与思考！