如何在数据库优先方法中设置创建日期和修改日期以进行加密 [英] How to set created date and Modified Date to enitites in DB first approach

问题描述

在我们应用程序的每个SQL表中，都有 CreatedDate和 ModifiedDate列。我们正在使用数据库优先方法。当我保存数据时，我希望自动填充这两列。一种方法是在SQL表列本身上将默认值设置为 getdate（）。这样就可以部分解决问题。表示它将设置CreatedDate&实体为新时的ModifiedDate。
但是，当我编辑/更新实体时，我只希望更新 ModifiedDate 。

有很多文章使用代码来完成。第一种方法。但是我们正在使用数据库优先方法。

我在这里有什么选择？

In every SQL table in our application we have "CreatedDate" and "ModifiedDate" column. We are using DB first approach. When i save the data, i want these two column automatically populated. One approach is to have Default Value as getdate() on the SQL Table Column itself. So thats going to solve the problem partially. Meaning it will set the CreatedDate & ModifiedDate when entity is new. However when i am editing/updating the entity i want only ModifiedDate to be updated.
There are lot of articles doing it using Code first approach. But we are using DB first approach.
What are my options here?

推荐答案

我更喜欢通用方法如下：

I like a more generic approach used like this:

interface IEntityDate
{
    DateTime CreatedDate { get; set; }

    DateTime UpdatedDate { get; set; }
}

public abstract class EntityBase<T1>: IEntityDate
{
    public T1 Id { get; set; }

    public virtual DateTime CreatedDate { get; set; }
    public virtual string CreatedBy { get; set; }
    public virtual DateTime UpdatedDate { get; set; }
    public virtual string UpdatedBy { get; set; }
}

public override int SaveChanges()
{
    var now = DateTime.Now;

    foreach (var changedEntity in ChangeTracker.Entries())
    {
        if (changedEntity.Entity is IEntityDate entity)
        {
            switch (changedEntity.State)
            {
                case EntityState.Added:
                    entity.CreatedDate = now;
                    entity.UpdatedDate = now;
                    break;

                case EntityState.Modified:
                    Entry(entity).Property(x => x.CreatedDate).IsModified = false;
                    entity.UpdatedDate = now;
                    break;
            }
        }
    }

    return base.SaveChanges();
}

更新：

要处理 CreatedBy 和 UpdatedBy ，我使用DbContext的包装器，如下所示：

To handle CreatedBy and UpdatedBy I use a wrapper for DbContext like this:

public interface IEntity
{
    DateTime CreatedDate { get; set; }

    string CreatedBy { get; set; }

    DateTime UpdatedDate { get; set; }

    string UpdatedBy { get; set; }
}

public interface ICurrentUser
{
    string GetUsername();
}

public class ApplicationDbContextUserWrapper
{
    public ApplicationDbContext Context;

    public ApplicationDbContextUserWrapper(ApplicationDbContext context, ICurrentUser currentUser)
    {
        context.CurrentUser = currentUser;
        this.Context = context;
    }
}

public class ApplicationDbContext : DbContext
{

    public ICurrentUser CurrentUser;

    public override int SaveChanges()
    {
        var now = DateTime.Now;

        foreach (var changedEntity in ChangeTracker.Entries())
        {
            if (changedEntity.Entity is IEntity entity)
            {
                switch (changedEntity.State)
                {
                    case EntityState.Added:
                        entity.CreatedDate = now;
                        entity.UpdatedDate = now;
                        entity.CreatedBy = CurrentUser.GetUsername();
                        entity.UpdatedBy = CurrentUser.GetUsername();
                        break;
                    case EntityState.Modified:
                        Entry(entity).Property(x => x.CreatedBy).IsModified = false;
                        Entry(entity).Property(x => x.CreatedDate).IsModified = false;
                        entity.UpdatedDate = now;
                        entity.UpdatedBy = CurrentUser.GetUsername();
                        break;
                }
            }
        }

        return base.SaveChanges();
    }

    ...

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