如何从 EF Core/.NET Core 2.0 中的实体名称获取 DbSet [英] How to get DbSet from entity name in EF Core / .NET Core 2.0

问题描述

我有一个 DbContext 和几个 DbSet 属性:

I have a DbContext with several DbSet<T> properties:

public virtual DbSet<A> A { get; set; }
public virtual DbSet<B> B { get; set; }
public virtual DbSet<C> C { get; set; }
...

在某些情况下，我现在必须能够检索实体名称作为字符串的特定 DbSet(例如，当用户输入A"时，我需要获取 Dbset).

In certain scenarios I must now be able to retrieve a specific DbSet with the entity name as string (e.g. when the user enters "A", I need to get the Dbset<A>).

在以前的 EF 版本中，以下是可能的:

In previous EF versions, the following was possible:

var dbset = Context.Set(Type.GetType(A));

当前版本的 EF 核心是否有类似的方法?我已经尝试了几种方法来实现这一点，但目前我让它工作的唯一方法是使用一个相当丑陋的开关/外壳，我想摆脱它.

Is there a similar way to do so with the current versions of EF core? I've tried several ways to achieve that, but the only way I have it working at the moment is using a rather ugly switch/case and I would like to get rid of that.

我在这里发现了几篇有类似问题的帖子，但它们都与早期的 .NET Core 版本或 EF5/EF6 相关.

I've found several posts with similar issues around here, but all of them relate to early .NET Core versions or EF5 / EF6.

推荐答案

这样做是为了在 de dbcontext 类中添加 de extension Set(Type t) 方法.

Do this to add de extension Set(Type t) method to de dbcontext class.

using Microsoft.EntityFrameworkCore;

namespace ApiWebApplication.Utils
{
    public static class MyExtensions 
    {
        public static IQueryable<object> Set (this DbContext _context, Type t)
        {
            return (IQueryable<object>)_context.GetType().GetMethod("Set").MakeGenericMethod(t).Invoke(_context, null);
        }
    }
}

示例:

    // GET: api/Employees
    [HttpGet]
    public IEnumerable<object> GetEmployees()
    {
        return _context.Set(typeof(Employee));
    }

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