c# - 无法转换 EntityEntry 当前值

Question

我在 EF 6 中有相同的方法并且工作得很好，但是使用 EF core v1.1.1 是方法抛出这样的异常。请看一下。

     public virtual T Update(T obj)
    {
        try
        {
            if (null == obj) throw new ArgumentNullException(nameof(obj));

            _context.Set<T>().Attach(obj);

            var entry = _context.Entry(obj);

            foreach (var property in entry.OriginalValues.Properties)
            {
                var current = entry.CurrentValues.GetValue<object>(property.Name); // <-- error occurring this line. If i set the generic type to specific like int,string etc the code work for the specific type only but if i set to object won't work.
                entry.Property(property.Name).IsModified = current != null;
            }

            _context.SaveChanges();

            //Detached the current context to get changes value
            _context.Entry(obj).State = EntityState.Detached;

            return obj;
        }
        catch (Exception ex)
        {

            Console.Write(ex);
            throw;
        }
    }

Answer 1

使用索引器无需强制转换即可获取属性值:

var current = entry.CurrentValues[property.Name];

主键属性应该从 foreach 循环中排除。像这样的东西:

if (property.Name == "Id") continue;

应该可以。否则你会得到InvalidOperationException:

'The property 'Id' on entity type 'Foo' is part of a key and so cannot be modified or marked as modified.'