实体框架自引用表。如何让父母到达root [英] Entity Framework self referencing table. How to get parent until reach to root

问题描述

我有一个自引用表，我需要绑定日期从表到树视图用户控制。我使用BuildThree（）方法来获取孩子。我的问题是，如何使用我的View模型获取父母，直到父母使用

我的实体：

  public partial class Category 
 {
 
 public Category（）
 {
 this.children = new HashSet< Category>（） ; 
} 
 
 public int CategoryId {get;组; } 
 public string CategoryName {get;组; } 
 public Nullable< int> ParentCategoryId {get;组; } 
 
 public virtual ICollection< Category>孩子{get;组; } 
 public virtual Category Parent {get;组; } 
} 
  

我的查看模型：

  public class TreeViewModel 
 {
 public TreeViewModel（）
 {
 this.children = new HashSet< TreeViewModel>（）; 
} 
 
 public int id {get;组; } 
 
 public string text {get;组; } 
 
 public virtual TreeViewModel MyParent {get;组; } 
 
 public virtual IEnumerable< TreeViewModel>孩子{get;组; } 
 
} 
  

这是我用来获取孩子的方法

  public IEnumerable< TreeViewModel> BuildThree（IEnumerable< Category>类别，int？parentCategoryId = null）
 {
 if（categories == null）
 return null; 
 var result = categories.Select（c => new TreeViewModel（）
 {
 id = c.CategoryId，
 text = c.CategoryName，
 
 children = BuildThree（c.children，c.CategoryId）
}）; 
返回结果; 
} 
 
 
 
 
 
 Database1Entities db = new Database1Entities（）; 
 var category = db.Categories.Find（id）; 
 
 TreeViewModel vm = new TreeViewModel（）; 
 vm.id = category.CategoryId; 
 vm.text = category.CategoryName; 
 
 vm.children = BuildThree（category.children）; 
  

解决方案

如果您只是寻找一种填充 MyParent propperty，而不必对 BuildThree 方法进行小的更改。

  public IEnumerable< TreeViewModel> BuildThree（IEnumerable< Category>类别，TreeViewModel parentCategory）
 {
 if（categories == null）
返回null; 
 var result = new List< TreeViewModel>（）; 
 foreach（var category in categories）
 {
 var treeViewModel = new TreeViewModel（）; 
 treeViewModel.Id = category.CategoryId，
 treeViewModel.Text = category.CategoryName，
 treeViewModel.MyParent = parentCategory; 
 treeViewModel.Children = BuildThree（category.children，treeViewModel）; 
 result.Add（treeViewModel）; 
} 
返回结果; 
} 
  

I have a self referencing table and i need to bind the date from table to tree view user control . I use BuildThree() method to get children. My question is how can i get parent until reach to root parent using my View model

My Entity:

 public partial class Category
        {

            public Category()
            {
                this.children = new HashSet<Category>();
            }

            public int CategoryId { get; set; }
            public string CategoryName { get; set; }
            public Nullable<int> ParentCategoryId { get; set; }

            public virtual ICollection<Category> children { get; set; }
            public virtual Category Parent { get; set; }
        }

my view model:

public class TreeViewModel
{
        public TreeViewModel()
        {
            this.children = new HashSet<TreeViewModel>();
        }

        public int id { get; set; }

        public string text { get; set; }

        public virtual TreeViewModel MyParent { get; set; }

        public virtual IEnumerable<TreeViewModel> children { get; set; }

    }

And this is the method i use to get children

   public IEnumerable<TreeViewModel> BuildThree(IEnumerable<Category> categories, int? parentCategoryId = null)
    {
        if (categories == null)
            return null;
        var result = categories.Select(c => new TreeViewModel()
        {     
            id = c.CategoryId,
            text = c.CategoryName,

            children = BuildThree(c.children, c.CategoryId)
        });
        return result;
    }





        Database1Entities db = new Database1Entities();
        var category = db.Categories.Find(id);

        TreeViewModel vm = new TreeViewModel();
        vm.id = category.CategoryId;
        vm.text = category.CategoryName;

        vm.children = BuildThree(category.children);

解决方案

If you just looking for a way to populate MyParent propperty, than have to make small changes of your BuildThree method.

public IEnumerable<TreeViewModel> BuildThree(IEnumerable<Category> categories, TreeViewModel parentCategory)
    {
        if (categories == null)
            return null;
        var result = new List<TreeViewModel>();
        foreach (var category in categories)
        {
           var treeViewModel = new TreeViewModel();
           treeViewModel.Id = category.CategoryId,
           treeViewModel.Text = category.CategoryName,
           treeViewModel.MyParent = parentCategory; 
           treeViewModel.Children= BuildThree(category.children,treeViewModel);
           result.Add(treeViewModel);   
        }
        return result;
    }

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