.NET Core连接数据库

DbContext：

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using System;
using WebApi.Models;

namespace WebApi.Data
{
    public class DataMgrContext : DbContext
    {
        public readonly static IConfiguration configuration;
        static DataMgrContext()
        {
            configuration = new ConfigurationBuilder()
            .SetBasePath(Environment.CurrentDirectory)
            .AddJsonFile("appsettings.json", true, true)
            .AddInMemoryCollection()
            .Build();
        }
        public static string connectionString
        {
            get { return configuration["ConnectionStrings:Default"]; }
        }

        public DataMgrContext(DbContextOptions<DataMgrContext> options)
            : base(options)
        {
        }
        public DataMgrContext() { }
        
        public DbSet<SysUser> SysUsers{ get; set; }
        public DbSet<Permission> Permissions { get; set; }
        public DbSet<Role> Roles { get; set; }
        public DbSet<RolePermission> RolePermissions { get; set; }
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            //映射数据库表名
            //modelBuilder.Entity<Role>().ToTable("Role");
        }
        protected override void OnConfiguring(DbContextOptionsBuilder options)
        {
            options.UseSqlServer(connectionString);
        }
    }
}

appSettings.json

"ConnectionStrings": {
    "Default": "Data Source=.;Initial Catalog=efcoretest;User ID=sa;Password=111111"
  },

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<DataMgrContext>();//注入数据库服务
    //...
}

　　使用

using (var db = new DataMgrContext())
{
    db.Blogs.Add(dto);
    db.SaveChanges();
}

//2
private readonly DataMgrContext db;
public BlogController(DataMgrContext context)
{
    db = context;
}