Question

我的程序中是否有任何改进的余地，可以将平面数据库实体转换为树数据结构。我不想失去通用灵活性，因为我应该能够对任何其他DBEntity类使用相同的方法

数据库实体类的接口

public interface IDbEntityNode
    {
         int Id { get; set; }
         int ParentId { get; set; }
    }

数据库实体类的示例

 public class ExceptionCategory :IDbEntityNode
    {
        public  int Id { get; set; }
        public  int ParentId { get; set; }
        public string Data { get; set; }      
        public ExceptionCategory(string data, int id, int parentId)
        {
            Id = id;
            ParentId = parentId;
            Data = data;
        }
    }

具有树节点结构的通用类

public class GenericNode<T> 
    {
        public T NodeInformation { get; set; }
        public GenericNode<T> Parent { get; set; }
        public List<GenericNode<T>> Children { get; set; } = new List<GenericNode<T>>();
    }

将平面列表隐藏到树中的方法

public static List<GenericNode<T>> CreateGenericTree<T>(List<T> flatDataObject,Func<T,bool> IsRootNode) where T : IDbEntityNode            
        {
            var lookup = new Dictionary<int, GenericNode<T>>();
            var rootNodes = new List<GenericNode<T>>();
            var noOfElements = flatDataObject.Count;
            for (int element = 0; element < noOfElements; element++)
            {
                GenericNode<T> currentNode;
                if (lookup.TryGetValue(flatDataObject[element].Id, out currentNode))
                {
                    currentNode.NodeInformation = flatDataObject[element];
                }
                else
                {
                    currentNode = new GenericNode<T>() { NodeInformation = flatDataObject[element] };
                    lookup.Add(flatDataObject[element].Id, currentNode);
                }

                if (IsRootNode(flatDataObject[element])) 
                {
                    rootNodes.Add(currentNode);
                }
                else
                {
                    GenericNode<T> parentNode;
                    if (!lookup.TryGetValue(flatDataObject[element].ParentId, out parentNode))
                    {   
                        parentNode = new GenericNode<T>();
                        lookup.Add(flatDataObject[element].ParentId, parentNode);
                    }
                    parentNode.Children.Add(currentNode);
                    currentNode.Parent = parentNode;
                }
            }

            return rootNodes;
        }

执行：

private static void Main(string[] args)
        {
            List<IDbEntityNode> flatDataStructure = new List<IDbEntityNode>
            {
                new ExceptionCategory("System Exception",1,0),
                new ExceptionCategory("Index out of range",2,1),
                new ExceptionCategory("Null Reference",3,1),
                new ExceptionCategory("Invalid Cast",4,1),
                new ExceptionCategory("OOM",5,1),
                new ExceptionCategory("Argument Exception",6,1),
                new ExceptionCategory("Argument Out Of Range",7,6),
                new ExceptionCategory("Argument Null",8,6),
                new ExceptionCategory("External Exception",9,1),
                new ExceptionCategory("Com",10,9),
                new ExceptionCategory("SEH",11,9),
                new ExceptionCategory("Arithmatic Exception",12,1),
                new ExceptionCategory("DivideBy0",13,12),
                new ExceptionCategory("Overflow",14,12),
            };

            var tree = CreateGenericTree(flatDataStructure, IsRootNode);
        }
 private static bool IsRootNode(IDbEntityNode dbEntity)
        {
            bool isRootNode = false;
            if (dbEntity.ParentId == 0 )
                isRootNode = true;
            return isRootNode;              
        }

Answer 1

创建了一种通用方法，表对象需要遵循dbSet接口，而TreeNode对象需要遵循ITreeNode。我使用binarySerach使其尽可能快。无需递归。逻辑确保您不需要按特定顺序放置物品。当仍然存在未分配的对象时，我没有在循环外抛出错误，这很容易添加。

#ifdef BUILDING_MYDLL
#define MYDLL_EXPORT __declspec(dllexport)
#else
#define MYDLL_EXPORT __declspec(dllimport)
#endif

class MYDLL_EXPORT Exported
{
};

Answer 2

尝试使用递归代码执行以下解决方案：

    Set-ID3v1 -path "c:\users\me\Desktop\Test.mp3" -Year 1996 -Title "This is a test"

在树中转换表

2 个答案: