展平父/子对象链，沿途合并值

本文关键字：合并 对象 | 更新日期: 2023-09-27 18:27:22

我们已经关注这个问题很长时间了，浪费了宝贵的时间。

我们有这些对象，让我们称它们为组件。我们的应用程序允许您在现有组件的基础上创建新组件

父级的所有值都是"继承的"（读作：可通过component.Parent属性访问），除非重写一个值——例如，您想给它一个新名称，但保留其余的父级值。

// Exiting parent-child object chain
BaseObject      {Id = 1, Name = "Base", Description = "Base description", Notes = "Awesome object", ParentId = null}
ChildObject1    {Id = 2, Name = "", Description = "", Notes = "", ParentId = 1}
ChildObject2    {Id = 3, Name = "Custom Name", Description = "", Notes = "", ParentId = 2}
ChildObject3    {Id = 4, Name = "", Description = "Final object", Notes = "", ParentId = 3}

现在，我想从上到下将其展开，将父对象的现有值用于子对象上的任何空值。

// End result after flattening/merging
ChildObject3    {Id = 4, Name = "Custom Name", Description = "Final object", Notes = "Awesome object", ParentId = 3}

值得注意的是：没有子属性，只有子属性知道父属性。家长不知道孩子。

如何在不使用丑陋的while(child.Parent != null)构造和创建previousComponent、currentComponent等对象来跟踪集合值的情况下解决此问题。

展平父/子对象链，沿途合并值

递归DeepCopy方法怎么样，比如：

public class ComponentClass()
{
   public ComponentClass DeepCopy(ComponentClass comp)
   {
       CopyAllNonEmptyPropertiesTo(comp);
       if (comp.StillHasEmptyProperties())
          return Parent.DeepCopy(comp);
       else
          return comp;
   }
}

创建数据对象的字典，以便查找父对象。

对于您拥有的每个项，在以下情况下对父值进行递归查找：

  • 您没有目标属性之一的值
  • 你有父母

例如（Dump（）命令来自LinqPad）

var data = new List<Bob>
{
    new Bob { Id = 1, Name = "Base", Description = "Base description", Notes = "Awesome object", ParentId = null },
    new Bob { Id = 2, Name = "", Description = "", Notes = "", ParentId = 1 },
    new Bob { Id = 3, Name = "Custom Name", Description = "", Notes = "", ParentId = 2 },
    new Bob { Id = 4, Name = "", Description = "Final object", Notes = "", ParentId = 3 },
};
var map = data.ToDictionary(d => d.Id, d => d);
data.ForEach(row => CopyFromParent(map, row, row.ParentId.HasValue ? map[row.ParentId.Value] : null));
data.Dump();
}
void CopyFromParent(Dictionary<int, Bob> map, Bob target, Bob current)
{
    // set properties
    if (current != null && string.IsNullOrEmpty(target.Name) && !string.IsNullOrEmpty(current.Name)) target.Name = current.Name;
    if (current != null && string.IsNullOrEmpty(target.Description) && !string.IsNullOrEmpty(current.Description)) target.Description = current.Description;
    if (current != null && string.IsNullOrEmpty(target.Notes) && !string.IsNullOrEmpty(current.Notes)) target.Notes = current.Notes;
    // dive deeper if we need to, and if we can
    var needToDive = string.IsNullOrEmpty(target.Name) || string.IsNullOrEmpty(target.Description) || string.IsNullOrEmpty(target.Notes);
    var canDive = current != null && current.ParentId.HasValue && map.ContainsKey(current.ParentId.Value);
    if (needToDive && canDive)
    {
        CopyFromParent(map, target, map[current.ParentId.Value]);
    }
}
class Bob
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string Notes { get; set; }
    public int? ParentId { get; set; }
}
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