Question

我目前正在寻找正确检查我的授权框架是否已添加，修改或删除的方法。以下是我的编码：

    int state = 0;

    var added = this.ChangeTracker.Entries().Where(e => e.State == EntityState.Added).ToList();
    var modified = this.ChangeTracker.Entries().Where(e => e.State == EntityState.Modified).ToList();
    var deleted = this.ChangeTracker.Entries().Where(e => e.State == EntityState.Deleted).ToList();

        if (added.Count > 0)
            state = 1;
        if (modified.Count > 0)
            state = 2;
        if (deleted.Count > 0)
            state = 3;

目前正在运作。我只想知道是否还有其他正确的方法。

Answer 1

改善表现

您可以使用Any而不是创建包含所有实体的列表。
如果找到上一个

state

代码：

int state = 0;

if (this.ChangeTracker.Entries().Any(e => e.State == EntityState.Deleted))
{
    state = 3;
}
else if (this.ChangeTracker.Entries().Any(e => e.State == EntityState.Modified))
{
    state = 2;
}
else if (this.ChangeTracker.Entries().Any(e => e.State == EntityState.Added))
{
    state = 1;
}

Answer 2

如果您使用的是实体框架6，则可以override SaveChanges()

public override int SaveChanges() 
{
  var addedEntites= ChangeTracker.Entries<IfYouWantSpecifyAnyType>()
                         .Where(p => p.State == EntityState.Added)
                         .Select(p => p.Entity);

  var modified= ChangeTracker.Entries<IfYouWantSpecifyAnyType>()
                         .Where(p => p.State == EntityState.Modified)
                         .Select(p => p.Entity);

  var now = DateTime.UtcNow;

  foreach (var added in addedEntites) 
  {
    added.CreatedAt = now;
    added.LastModifiedAt = now;
  }

  foreach (var modified in modified) 
  {
    modified.LastModifiedAt = now;
  }

  return base.SaveChanges();
}

@Matthias Burger建议它会对性能产生影响，我也建议使用触发器或留在数据库端的东西。

添加，修改或删除检查实体框架

2 个答案: