Question

如何使用附加特定对象来更新模型及其子项？

我使用旧实体框架看起来像这样的存储库模式：

    public User UpdateUser(User user, IEnumerable<System.Linq.Expressions.Expression<Func<User, object>>> properties)
    {
        if (user.UserId == 0)
        {
            db.Users.Attach(user);
        }
        else
        {
            db.Users.Attach(user);
            ObjectStateEntry entry = db.ObjectStateManager.GetObjectStateEntry(user);
            foreach (var selector in properties)
            {
                string propertyName = PropertyToString(selector.Body);
                entry.SetModifiedProperty(propertyName);
            }
        }

        context.SaveChanges();
        return user;
    }

    private static string PropertyToString(Expression selector)
    {
        switch (selector.NodeType)
        {
            case ExpressionType.MemberAccess:
                return ((selector as MemberExpression).Member as PropertyInfo).Name;
                break;

            case ExpressionType.Convert:
                //Needed to recognize bool datatype
                return (((selector as UnaryExpression).Operand as MemberExpression).Member as PropertyInfo).Name;

                break;
        }
        throw new InvalidOperationException();
    }

但是现在，代码优先不支持db.ObjectStateManager。如何在分离对象的特定属性上运行更新？

Answer 1

您可以尝试使用：

context.Entry(user).Property(u => u.Body).IsModified = true;

上下文是DbContext派生类的实例。

Answer 2

尝试

var adapter = (IObjectContextAdapter)context;
adapter.ObjectContext.ObjectStateManager ...

实体框架代码首先更新分离的对象

2 个答案: