部分和元数据类不读取[key]值ef5 vs2010

Question

尝试实施

中的以下审核代码

https://jmdority.wordpress.com/2011/07/20/using-entity-framework-4-1-dbcontext-change-tracking-for-audit-logging/

对于密钥名称，它一直给出错误“序列不包含匹配元素”

我不想编辑系统生成的文件，因为对我的模型的任何更新都会导致我必须返回并进行编辑。我已使用im附加了部分和元数据类，但不知何故，上面找到的审计功能不是读取键值。

解决这个问题的运气好吗？

我首先使用ef5 DB并使用部分和元数据类

的元数据：

public class TABLEMetadata : ABCEntities.IDescribableEntity,
    ABCEntities.IAuditable
{
    [Key]
    public int X_ID { get; set; }
    [Required(ErrorMessage = "A Name is required!")]
    public string X_Name { get; set; }
    public int Deleted { get; set; }

    public string Describe()
    {
        return "{ X_ID : \"" + X_ID + "\", X_Name : \"" + X_Name + "\" }";
    }

}

PARTIAL CLASS

[MetadataType(typeof(TABLE.Metadata))]
public partial class TABLE
{ 
    private sealed class Metadata
    {
        [Key]
        public int X_ID { get; set; }
    }
}

public partial class ABCEntities 
{
    public interface IAuditable
    {

        int Deleted { get; set; }

    }

    public interface IDescribableEntity
    {

        string Describe();
    }

    public int SaveChangesNew()
    {
        ChangeTracker.DetectChanges(); // Important!
        var userId = System.Web.HttpContext.Current.User.Identity.Name;

        foreach (var ent in this.ChangeTracker.Entries().Where(p => p.State == System.Data.EntityState.Added || p.State == System.Data.EntityState.Deleted || p.State == System.Data.EntityState.Modified))
        {

            foreach (X_AuditLog x in GetAuditRecordsForChange(ent, userId))
            {
                this.X_AuditLog.Add(x);
            }
        }

        // Call the original SaveChanges(), which will save both the changes made and the audit records
        return base.SaveChanges();
    }

    private List<X_AuditLog> GetAuditRecordsForChange(DbEntityEntry dbEntry, string userId)
    {
        var auditEntity = dbEntry.Entity as IAuditable;
        List<X_AuditLog> result = new List<X_AuditLog>();
        DateTime changeTime = DateTime.Now;

       TableAttribute tableAttr = dbEntry.Entity.GetType().GetCustomAttributes(typeof(TableAttribute), false).SingleOrDefault() as TableAttribute;

       string tableName = tableAttr != null ? tableAttr.Name : dbEntry.Entity.GetType().Name;

       var keyObject = dbEntry.Entity.GetType().GetProperties().SingleOrDefault(p => p.GetCustomAttributes(typeof(KeyAttribute), false).Count() > 0);

        string keyName = keyObject != null ? keyObject.Name : "";

        if (dbEntry.State == System.Data.EntityState.Added)
        {
            auditEntity.Deleted = 0;

            result.Add(new X_AuditLog()
            {
                AuditLogID = Guid.NewGuid(),
                UserID = userId,
                EventDateUTC = changeTime,
                EventType = "A", // Added
                TableName = tableName,
                RecordID = dbEntry.CurrentValues.GetValue<object>(keyName).ToString(),  

                ColumnName = "*ALL",    
                NewValue = (dbEntry.CurrentValues.ToObject() is IDescribableEntity) ? (dbEntry.CurrentValues.ToObject() as IDescribableEntity).Describe() : dbEntry.CurrentValues.ToObject().ToString()
            });
        }
        else if (dbEntry.State == System.Data.EntityState.Modified)
        {
            foreach (string propertyName in dbEntry.OriginalValues.PropertyNames)
            {

                if (!object.Equals(dbEntry.GetDatabaseValues().GetValue<object>(propertyName),
                    dbEntry.CurrentValues.GetValue<object>(propertyName)))
                {
                    result.Add(new X_AuditLog()
                    {
                        AuditLogID = Guid.NewGuid(),
                        UserID = userId,
                        EventDateUTC = changeTime,
                        EventType = "M",    // Modified
                        TableName = tableName,
                        RecordID = dbEntry.OriginalValues.GetValue<object>(keyName).ToString(),
                        ColumnName = propertyName,
                        OriginalValue = dbEntry.OriginalValues.PropertyNames.ToString(),


                        NewValue = dbEntry.CurrentValues.GetValue<object>(propertyName) == null ? null : dbEntry.CurrentValues.GetValue<object>(propertyName).ToString()
                    });
                }
            }
        }
        else if (dbEntry.State == System.Data.EntityState.Deleted)
        {
            dbEntry.State = EntityState.Unchanged;
            auditEntity.Deleted = 1; //perform soft delete


            result.Add(new X_AuditLog()
            {
                AuditLogID = Guid.NewGuid(),
                UserID = userId,
                EventDateUTC = changeTime,
                EventType = "D", // Deleted
                TableName = tableName,
                RecordID = dbEntry.OriginalValues.GetValue<object>(keyName).ToString(),
                ColumnName = "*ALL",
                NewValue = (dbEntry.OriginalValues.ToObject() is IDescribableEntity) ? (dbEntry.OriginalValues.ToObject() as IDescribableEntity).Describe() : dbEntry.OriginalValues.ToObject().ToString()
            });
        }
        return result;
    }
}