Question

我正在尝试获取我在EF5应用程序中插入，更新或删除的每个条目的主键信息。我使用类似的代码：

//Get collection of each insert, update, or delete made on the entity. 
IEnumerable<DbEntityEntry> changedEntries = this.ChangeTracker.Entries()
    .Where(e => e.State == EntityState.Added
        || e.State == EntityState.Modified
        || e.State == EntityState.Deleted);

foreach (DbEntityEntry entry in changedEntries)
{
    //Get primary key collection
    EntityKey key = ((IObjectContextAdapter)this).ObjectContext.ObjectStateManager
        .GetObjectStateEntry(entry.Entity).EntityKey;

    string keyName;
    //Get name of first key. Make sure a collection was returned.
    if (key.EntityKeyValues != null)
        keyName = key.EntityKeyValues[0].Key;
    else
        keyName = "(NotFound)";
}

但是，此代码的问题在于，当将新记录插入数据库时，它无法正常工作。当条目状态为EntityState.Added时，key.EntityKeyValues具有空值（此代码将keyName的值设置为＆＃34;（NotFound）＆＃34;。

有没有办法在插入记录时获取主键的列名？

Answer 1

我找到了一种方法，将原始代码与Gert发布的链接中的代码相结合：

//Get collection of each insert, update, or delete made on the entity. 
IEnumerable<DbEntityEntry> changedEntries = this.ChangeTracker.Entries()
    .Where(e => e.State == EntityState.Added
        || e.State == EntityState.Modified
        || e.State == EntityState.Deleted);

foreach (DbEntityEntry entry in changedEntries)
{
    EntitySetBase setBase = ObjectContext.ObjectStateManager
        .GetObjectStateEntry(entry.Entity).EntitySet;

    string[] keyNames = setBase.ElementType.KeyMembers.Select(k => k.Name).ToArray();
    string keyName;
    if (keyNames != null)
        keyName = keyNames.FirstOrDefault();
    else
        keyName = "(NotFound)";
}

到目前为止，即使我添加了新记录，它似乎也在起作用。

Answer 2

在SaveChanges（）之后，您的主键就位。您可以在SaveChanges（）之前保留changedList，然后在SaveChanges（）之后保存更改日志。

参考http://webmisterradixlecti.blogspot.co.nz/2013/04/get-primary-key-on-insert-using-entity.html

添加时获取DBEntityEntry的主键

2 个答案: