c# - Npgsql.Entity Framework 7 无法使用 npgsql 服务器

Question

我是 C# 的新手。我在下面的 .UseNpgsql(string connectionString) 上看到了一些红色波浪线(错误下划线)。悬停错误告诉我，我可能没有使用正确的 using 语句。

using Microsoft.Data.Entity;

namespace Something.Context {

    public class OauthTokenContext : DbContext
    {
        public DbSet<Model.OauthToken> OauthTokens { get; set; }
        protected override void OnConfiguring(DbContextOptionsBuilder builder)
        {
            var connectionString = @"Server=localhost; Port=1337; User Id=tinganho; Password=secret; Database=hello";
            builder.UseNpgsql(connectionString);
        }
    }
}

在我的 project.json 中，我有以下依赖项:

"dependencies": {
    "Npgsql.EntityFramework7": "3.1.0-unstable0038",
    "Npgsql": "3.1.0-unstable0038"
}

在 startup.cs 中:

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Microsoft.AspNet.Builder;
using Microsoft.AspNet.Hosting;
using Microsoft.AspNet.Http;
using Microsoft.Framework.ConfigurationModel;
using Microsoft.AspNet.Routing;
using System.Linq;
using Microsoft.Data.Entity;
using Microsoft.Framework.DependencyInjection;

using Npgsql;
using Npgsql.EntityFramework7;

using Something.Context;
using Something.Model;

namespace Something
{
    public class Startup
    {
        public Startup(IHostingEnvironment env)
        {
        }

        // This method gets called by a runtime.
        // Use this method to add services to the container
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddEntityFramework()
                .AddDbContext<OauthTokenContext>();

            services.AddMvc();
            // Uncomment the following line to add Web API services which makes it easier to port Web API 2 controllers.
            // You will also need to add the Microsoft.AspNet.Mvc.WebApiCompatShim package to the 'dependencies' section of project.json.
            // services.AddWebApiConventions();
        }

        public IConfiguration Configuration { get; set; }

        // Configure is called after ConfigureServices is called.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            // Configure the HTTP request pipeline.
            app.UseStaticFiles();

            // Add MVC to the request pipeline.
            app.UseMvc();
            // Add the following route for porting Web API 2 controllers.
            // routes.MapWebApiRoute("DefaultApi", "api/{controller}/{id?}");
        }
    }
}

当我在 services.AddEntityFramework() 之后添加 .AddNpgsql() 时，我得到:

System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Framework.DependencyInjection.Abstractions' or one of its dependencies

Answer 1

你应该使用这种方法:

1) 进入Startup.ConfigureServices只添加services.AddEntityFrameworkNpgsql();

 public void ConfigureServices(IServiceCollection services)
 {
        //...
        services.AddEntityFrameworkNpgsql();
}

2) 入类继承DbContext:

public class DatabaseClass : DbContext 
{
    //...

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseNpgsql("my connection string");
    }
}