带字符串 PK 的 EF InsertOrUpdate

发布于 2024-12-09 02:47:07 字数 1251 浏览 0 评论 0原文

如果我有CurrencyId，我会做这样的事情：

 public void InsertOrUpdate(Currency entity)
        {
            if (entity.CurrencyId == default(int))
            {
                // New entity
                this.dbset.Add(entity);
            }
            else
            {
                // Existing entity
                this.context.Entry(entity).State = EntityState.Modified;
            }
        }

但我使用字符串CurrencyCode作为PK，并且我希望能够添加或编辑它。所以我必须检查数据库中是否存在CurrencyCode。我该怎么做？

添加新实体是可以的，但如果我尝试编辑：

 public void InsertOrUpdate(Currency entity)
        {
            if (GetByCurrency(entity.CurrencyCode) == null)
            {
                // New entity
                this.dbset.Add(entity);
            }
            else
            {
                // Existing entity
                this.context.Entry(entity).State = EntityState.Modified;
            }
        }

public Currency GetByCurrency(string currencyCode)
{
    return this.dbset.Find(currencyCode);
}

我得到

ObjectStateManager 中已存在具有相同键的对象。 ObjectStateManager 无法跟踪具有相同属性的多个对象关键。

在

this.context.Entry(entity).State = EntityState.Modified;

原文

If I had CurrencyId, I would do something like this:

 public void InsertOrUpdate(Currency entity)
        {
            if (entity.CurrencyId == default(int))
            {
                // New entity
                this.dbset.Add(entity);
            }
            else
            {
                // Existing entity
                this.context.Entry(entity).State = EntityState.Modified;
            }
        }

But I'm using a string CurrencyCode as a PK and I'd like to be able to Add or Edit it. So I have to check whether the CurrencyCode exists in the db or not. How do I do this?

Adding a new entity is ok, but if I try to Edit:

 public void InsertOrUpdate(Currency entity)
        {
            if (GetByCurrency(entity.CurrencyCode) == null)
            {
                // New entity
                this.dbset.Add(entity);
            }
            else
            {
                // Existing entity
                this.context.Entry(entity).State = EntityState.Modified;
            }
        }

public Currency GetByCurrency(string currencyCode)
{
    return this.dbset.Find(currencyCode);
}

I'm getting

An object with the same key already exists in the ObjectStateManager.
The ObjectStateManager cannot track multiple objects with the same
key.

this.context.Entry(entity).State = EntityState.Modified;

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

绝對不後悔。 2024-12-16 02:47:07

这是因为当您执行查找时，它会返回对象并在缓存中保留一个副本。然后您将添加一个新副本，因此有两个。

相反，您要做两件事之一。您可以修改查找返回的副本，如果您可以假设CurrencyCode == null意味着它不存在于数据库中，那么只需添加它或附加它。

所以，像这样：

var currency = GetByCurrency(entity.CurrencyCode);

if (currency == null)
     this.dbset.Add(entity);
else
     currency.Something = entity.Something;

That's because when you do the Find, it's returning the object and keeping a copy in the cache. You are then adding a new copy, so there are two.

Instead, you do one of two things. You either modify the copy returned by the find, if you can assume that CurrencyCode == null means it doesn't exist in the database, then just add it or attach it.

So, something like:

var currency = GetByCurrency(entity.CurrencyCode);

if (currency == null)
     this.dbset.Add(entity);
else
     currency.Something = entity.Something;

回复收藏 0 原文

~没有更多了~