标签:done console sep new efault created active tip ring
首先创建一个.net core控制台程序,添加实体类
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
namespace TreeEntityDemo
{
/// <summary>
/// 员工实体
/// </summary>
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
[ForeignKey(nameof(ManagerId))]
public int? ManagerId { get; set; }
public virtual Employee Manager { get; set; }
public virtual ICollection<Employee> Employees { get; set; }
}
}
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using System.IO;
namespace TreeEntityDemo
{
public class AppDbContext:DbContext
{
public AppDbContext()
{
}
public AppDbContext(DbContextOptions<AppDbContext> options):base(options)
{
}
public DbSet<Employee> Employees { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Employee>()
.HasMany(x => x.Employees)
.WithOne(x => x.Manager)
.HasForeignKey(x => x.ManagerId)
.OnDelete(DeleteBehavior.ClientSetNull);
}
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
var builder = new ConfigurationBuilder()
.SetBasePath(Directory.GetCurrentDirectory())
.AddJsonFile("appsettings.json");
var config = builder.Build();
optionsBuilder.UseSqlServer(config.GetConnectionString("TreeDemoDb"));
}
}
}
{
"ConnectionStrings": {
"TreeDemoDb": "Server=(localdb)\\MSSQLLocalDB;Database=TreeDemoDb;Trusted_Connection=True;MultipleActiveResultSets=true"
}
}
add-migration InitialCreate
using Microsoft.EntityFrameworkCore;
using System;
using System.Linq;
namespace TreeEntityDemo
{
class Program
{
static void Main(string[] args)
{
using (var context = new AppDbContext())
{
context.Database.EnsureCreated();
if (!context.Employees.Any())
{
context.Employees.AddRange(
new Employee()
{
Name = "Manager1"
},
new Employee()
{
Name = "Employee1"
},
new Employee()
{
Name = "Employee2"
},
new Employee()
{
Name = "Employee3"
}
);
}
context.SaveChanges();
}
//GetParent();
SetParent();
GetChildren();
Console.WriteLine("Done!");
}
public static void Find()
{
using (var context = new AppDbContext())
{
var employees = context.Employees.FirstOrDefault(t => t.Name == "Employee1");
Console.WriteLine(employees.Name);
Console.WriteLine(employees.Manager.Name);
}
}
/// <summary>
/// 删除所有
/// </summary>
static void RemoveAll()
{
using (var context = new AppDbContext())
{
var employees = context.Employees
.Where(t => !string.IsNullOrEmpty(t.Name));
context.RemoveRange(employees);
context.SaveChanges();
}
}
/// <summary>
/// 获取父类
/// </summary>
static void SetParent()
{
using (var context = new AppDbContext())
{
var employee1 = context.Employees.FirstOrDefault(t => t.Name == "Employee1");
var employee2 = context.Employees.FirstOrDefault(t => t.Name == "Employee2");
var employee3 = context.Employees.FirstOrDefault(t => t.Name == "Employee3");
var manager1 = context.Employees.FirstOrDefault(t => t.Name == "Manager1");
employee1.Manager = manager1;
employee2.Manager = manager1;
employee3.Manager = manager1;
context.Update(employee1);
context.Update(employee2);
context.Update(employee3);
context.SaveChanges();
}
}
/// <summary>
/// 获取子类
/// </summary>
static void GetParent()
{
using (var context = new AppDbContext())
{
var employee1 = context.Employees.Include(t=>t.Manager).FirstOrDefault(t => t.Name == "Employee1");
if (employee1.Manager==null)
{
Console.WriteLine("null");
}
else
{
Console.WriteLine(employee1.Manager.Name);
}
}
}
static void GetChildren()
{
using (var context = new AppDbContext())
{
var manager1 = context.Employees.FirstOrDefault(t => t.Name == "Manager1");
var children = context.Employees.Where(t => t.ManagerId == manager1.Id);
if (children!=null && children.Count()>0)
{
foreach (var item in children)
{
Console.WriteLine(item.Name);
}
}
}
}
static void DeleteParent()
{
using (var context = new AppDbContext())
{
var manager1 = context.Employees.FirstOrDefault(t => t.Name == "Manager1");
context.Employees.Remove(manager1);
context.SaveChanges();
}
}
}
}
c# entity framework core树状结构增删改查
标签:done console sep new efault created active tip ring
原文地址:https://www.cnblogs.com/AlexanderZhao/p/12640506.html