分类:
Net Core
第一步: 找到appsettings.json这个文件，修改如下:
{
"Logging": {
"LogLevel": {
"Default": "Warning"
}
},
"AllowedHosts": "*",
"ConnectionStrings": {
"BloggingDatabase": "Server=.;Database=数据库名称;Trusted_Connection=True;"
}
}
第二步: 创建一个类继承DbContext，
using Microsoft.EntityFrameworkCore;
using Model;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using System.Text;
namespace DAL
{
public class CoreFirst_DbContext: DbContext
{
public CoreFirst_DbContext(DbContextOptions<CoreFirst_DbContext> options) : base(options)
{
}
public DbSet<Post> Posts { get; set; }
public DbSet<Tag> Tags { get; set; }
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
//唯一约束,替代键
modelBuilder.Entity<PostTag>()
.HasKey(pt => new { pt.PostId, pt.TagId });
modelBuilder.Entity<PostTag>()
.HasOne(pt => pt.Post)
.WithMany(p => p.PostTags)
.HasForeignKey(pt => pt.PostId);
modelBuilder.Entity<PostTag>()
.HasOne(pt => pt.Tag)
.WithMany(t => t.PostTags)
.HasForeignKey(pt => pt.TagId);
}
}
public class Post
{
public int PostId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public List<PostTag> PostTags { get; set; }
}
public class Tag
{
public int TagId { get; set; }
public string remark { get; set; }
public List<PostTag> PostTags { get; set; }
}
public class PostTag
{
public int PostId { get; set; }
public Post Post { get; set; }
public int TagId { get; set; }
public Tag Tag { get; set; }
}
}
第三步:找到Startup.cs这个文件，找到它下面的ConfigureServices方法并添加
services.AddDbContext<CoreFirst_DbContext>(options =>
options.UseSqlServer(Configuration.GetConnectionString("BloggingDatabase")));
第四步:然后添加数据迁移，更新数据库，就完成了多对多关系数据库的配置。评价
