我有几堂课。
test.cs中
class Test
{
public int TestId { get; set; }
public string Name { get; set; }
public ICollection<LevelNode> Nodes { get; set; }
public ICollection<AttributeNode> AttributeNodes { get; set; }
public Test()
{
Nodes = new Collection<LevelNode>();
AttributeNodes = new Collection<AttributeNode>();
}
}
Node.cs
abstract class Node
{
public int NodeId { get; set; }
public string Key { get; set; }
public string Value { get; set; }
public virtual Node ParentNode { get; set; }
public virtual ICollection<AttributeNode> Attributes { get; set; }
public Test Test { get; set; }
public Node()
{
Attributes = new Collection<AttributeNode>();
}
}
LevelNode.cs
class LevelNode : Node
{
public virtual ICollection<LevelNode> Nodes { get; set; }
public LevelNode() : base()
{
Nodes = new Collection<LevelNode>();
}
}
AttributeNode.cs
class AttributeNode : Node
{
public int Source { get; set; }
public AttributeNode() : base()
{
}
}
TestCFContext.cs
class TestCFContext : DbContext
{
public DbSet<Test> Tests { get; set; }
public TestCFContext()
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
}
}
主要功能:
static void Main(string[] args)
{
// Test
Test t = new Test() { Name = "My Test" };
// Root & sub
LevelNode root = new LevelNode() { Key = "root", Test = t };
LevelNode sub = new LevelNode() { Key = "sub1", Test = t, ParentNode = root };
root.Nodes.Add(sub);
t.Nodes.Add(root);
// Attr1
AttributeNode attr1 = new AttributeNode() { Key = "Attr1 key", Value = "Attr1 value", Source = 1, Test = t, ParentNode = sub };
AttributeNode subattr1 = new AttributeNode() { Key = "Subattr1 key", Value = "Subattr1 value", Source = 2, Test = t, ParentNode = attr1 };
attr1.Attributes.Add(subattr1);
sub.Attributes.Add(attr1);
// Attr2
sub.Attributes.Add(new AttributeNode() { Key = "Attr2 key", Value = "Attr2 value", Source = 3, Test = t, ParentNode = sub });
// Add to DB
TestCFContext c = new TestCFContext();
c.Tests.Add(t);
c.SaveChanges();
// Perform search
IEnumerable<AttributeNode> resultAttributes = t.AttributeNodes.Where(x => x.Key == "Attr2 key" && x.Value == "Attr2 value");
// => 0 results! :-(
}
我想要完成的事情如下。所有LevelNodes和LevelAttributes(都是来自Node的派生类)都包含对Test对象的引用。保存节点层次结构后,我想用特定的键和值搜索测试中的节点。
数据存储在数据库中,但是当我使用Test的AttributeNodes属性搜索特定属性时,没有找到结果。此外,在数据库中,Nodes表包含引用Tests表的3(!)列,其中大多数值为NULL。
NodeId Key Value Source Discriminator Node_NodeId ParentNode_NodeId Test_TestId LevelNode_NodeId Test_TestId1 Test_TestId2
1 root NULL NULL LevelNode NULL NULL 1 NULL NULL 1
2 sub1 NULL NULL LevelNode NULL 1 1 1 NULL NULL
3 Attr1 key Attr1 value 1 AttributeNode 2 2 1 NULL NULL NULL
4 Subattr1 key Subattr1 value 2 AttributeNode 3 3 1 NULL NULL NULL
5 Attr2 key Attr2 value 3 AttributeNode 2 2 1 NULL NULL NULL
是否可以简单地在数据库中为Test表提供一个外键,并在使用Test类的Nodes和AttributeNodes属性查询时产生预期结果? 如果使用EF Code First无法做到这一点,那么实现这一目标的最佳替代方法是什么?
答案 0 :(得分:0)
1)你有一点小错误
IEnumerable<AttributeNode> resultAttributes = t.AttributeNodes.Where(x => x.Key == "Attr2 key" && x.Value == "Attr2 value");
应该是
IEnumerable<AttributeNode> resultAttributes = c.AttributeNodes.Where(x => x.Key == "Attr2 key" && x.Value == "Attr2 value");
2)您已经声明了三种不同的外键关系Node - &gt;测试(在node.cs中),AttributeNode - &gt;测试和LevelNode - &gt;在(test.cs)中进行测试。我认为你必须像这样建模:
using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
namespace ConsoleApp8
{
class Test
{
public int TestId { get; set; }
public string Name { get; set; }
public ICollection<Node> Nodes { get; } = new HashSet<Node>();
public IEnumerable<LevelNode> LevelNodes
{
get
{
return Nodes.OfType<LevelNode>();
}
}
public IEnumerable<AttributeNode> AttributeNodes
{
get
{
return Nodes.OfType<AttributeNode>();
}
}
}
abstract class Node
{
public int NodeId { get; set; }
public string Key { get; set; }
public string Value { get; set; }
public virtual Node ParentNode { get; set; }
public virtual ICollection<AttributeNode> Attributes { get; } = new HashSet<AttributeNode>();
public Test Test { get; set; }
}
class LevelNode : Node
{
public virtual ICollection<LevelNode> Nodes { get; } = new HashSet<LevelNode>();
}
class AttributeNode : Node
{
public int Source { get; set; }
}
class TestCFContext : DbContext
{
public DbSet<Test> Tests { get; set; }
public DbSet<LevelNode> LevelNodes { get; set; }
public DbSet<AttributeNode> AttributeNodes { get; set; }
public TestCFContext()
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
}
}
class Program
{
static void Main(string[] args)
{
Database.SetInitializer(new DropCreateDatabaseAlways<TestCFContext>());
// Test
Test t = new Test() { Name = "My Test" };
// Root & sub
LevelNode root = new LevelNode() { Key = "root", Test = t };
LevelNode sub = new LevelNode() { Key = "sub1", Test = t, ParentNode = root };
root.Nodes.Add(sub);
t.Nodes.Add(root);
// Attr1
AttributeNode attr1 = new AttributeNode() { Key = "Attr1 key", Value = "Attr1 value", Source = 1, Test = t, ParentNode = sub };
AttributeNode subattr1 = new AttributeNode() { Key = "Subattr1 key", Value = "Subattr1 value", Source = 2, Test = t, ParentNode = attr1 };
attr1.Attributes.Add(subattr1);
sub.Attributes.Add(attr1);
// Attr2
sub.Attributes.Add(new AttributeNode() { Key = "Attr2 key", Value = "Attr2 value", Source = 3, Test = t, ParentNode = sub });
// Add to DB
using (TestCFContext c = new TestCFContext())
{
c.Database.Log = m => Console.WriteLine(m);
c.Tests.Add(t);
c.SaveChanges();
}
using (TestCFContext c = new TestCFContext())
{
c.Database.Log = m => Console.WriteLine(m);
// Perform search
IEnumerable<AttributeNode> resultAttributes = c.AttributeNodes.Where(x => x.Key == "Attr2 key" && x.Value == "Attr2 value");
var numFound = resultAttributes.Count();
Console.WriteLine($"{numFound} found.");
}
Console.WriteLine("Hit any key to exit");
Console.ReadKey();
}
}
}