.net 6 efcore一个model映射到多张表(非使用IEntityTypeConfiguration)

现在有两张表，结构一模一样，我又不想创建两个一模一样的model，就想一个model映射到两张表

废话不多说直接上代码

1. 安装依赖包
   
2. 创建model

namespace oneModelMultiTable.Model
{public class Test{public int id { get; set; }public string name { get; set; }public string tablename { get; set; }}
}

3. 创建DBContext
   我们需要使用tablename 动态指定表名，因此需要在DBContext中添加这个属性

namespace oneModelMultiTable
{public class DBHelper:DbContext{public DbSet<Test> testConfigs { get; set; }public string tablename { get; set; }public DBHelper(DbContextOptions<DBHelper> options):base(options){}protected override void OnModelCreating(ModelBuilder modelBuilder){modelBuilder.Entity<Test>(b =>{b.ToTable(tablename);b.HasKey(p => p.id);});base.OnModelCreating(modelBuilder);//modelBuilder.ApplyConfigurationsFromAssembly(this.GetType().Assembly);}}
}

4. 创建DynamicModelCacheKeyFactory 继承IModelCacheKeyFactory

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Infrastructure;
namespace oneModelMultiTable
{public class DynamicModelCacheKeyFactory : IModelCacheKeyFactory{public object Create(DbContext context, bool designTime){object p = context is DBHelper dynamicContext? (context.GetType(), dynamicContext.tablename): (object)context.GetType();return p;}}
}

5. 依赖注入

builder.Services.AddDbContext<DBHelper>(options =>
{options.UseNpgsql(@"Host=192.168.214.133;Port=32222;Database=postgresdb;Username=postgresadmin;Password=admin123").ReplaceService<IModelCacheKeyFactory, DynamicModelCacheKeyFactory>();
});

6. 创建controller

using Microsoft.AspNetCore.Mvc;
using oneModelMultiTable.Model;// For more information on enabling Web API for empty projects, visit https://go.microsoft.com/fwlink/?LinkID=397860namespace oneModelMultiTable.Controllers
{[Route("api/[controller]/[action]")][ApiController]public class TestController : ControllerBase{public readonly DBHelper dBHelper;public TestController(DBHelper _DBHelper){dBHelper = _DBHelper;}// GET: api/<TestController>[HttpGet]public List<Test> Get(string tablename){dBHelper.tablename = tablename;return dBHelper.testConfigs.ToList();}}
}

原理
你可能想通过ToTable()方法来更改表名，但是我们如何在OnModelCreating方法中更改表名呢?当EF构建模型时，它只运行OnModelCreating一次。

对于这个场景，我们需要通过使用IModelCacheKeyFactory来更改默认映射，它允许我们连接到模型缓存机制，以便EF可以根据其属性创建不同的模型。
EF使用IModelCacheKeyFactory为模型生成缓存键。

https://yanxiaodi.medium.com/mapping-the-model-to-multiple-tables-with-entityframework-core-b46bdeed8661

https://medium.com/@pawel.gerr/entity-framework-core-changing-database-schema-at-runtime-dcf1211768c6

https://github.com/xdqt/asp.net-core/tree/master/oneModelMultiTable