从ASP.NET Core 2 MVC应用程序中的appsettings.json存储/检索connectionString

在中定义连接字符串 appsettings.json

{
    "connectionStrings": {
        "appDbConnection: : "..."
    }
}

启动时读取其值

如果遵循约定并在下面定义连接字符串 connectionStrings ,可以使用扩展方法 GetConnectionString() 读取它的值。

public class Startup
{
    public IConfiguration Configuration { get; private set; }

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        // Since you said you're using Dapper, I guess you might want to
        // inject IDbConnection?
        services.AddTransient<IDbConnection>((sp) => 
            new SqlConnection(this.Configuration.GetConnectionString("appDbConnection"))
        );

        // ...
    }
}

在存储库中使用IDBConnection?

public interface ISpecificationRepository
{
    Specification GetById(int specificationId);
}

public SpecificationRepository : ISpecificationRepository
{
    private readonly IDbConnection _dbConnection;

    public SpecificationRepository(IDbConnection dbConnection)
    {
        _dbConnection = dbConnection;
    }

    public Specification GetById(int specificationId)
    {
        const string sql = @"SELECT * FROM [YOUR_TABLE]
                             WHERE Id = @specId;";

        return _dbConnection
            .QuerySingleOrDefault<Specification>(sql,
                new { specId = specificationId });
    }
}

只需要POCO中的连接字符串?

您可以使用 Options Pattern .

1. 定义一个与 JSON appsettings.json中的对象结构

   public class ConnectionStringConfig
   {
       public string AppDbConnection { get; set; }
   }
   

2. 启动时注册该配置

   public void ConfigureServices(IServiceCollection services)
   {
      // ...
   
      services.Configure<ConnectionStringConfig>(
          this.Configuration.GetSection("connectionStrings")
      );
   
      // ...
   }
   

3. 接收Poco中的访问器

   public class YourPoco
   {
       private readonly ConnectionStringConfig _connectionStringConfig;
   
       public YourPoco(IOptions<ConnectionStringConfig> configAccessor)
       {
           _connectionStringConfig = configAccessor.Value;
   
           // Your connection string value is here:
           // _connectionStringConfig.AppDbConnection;
       }
   }
   

笔记:

1. 见 my sample codes 关于如何从核心1.x和2.0上的appsettings.json读取值。
2. 见 how I setup 如果有多个连接字符串。

只需在appsettings.json中如下所示。

"ConnectionStrings": {
    "DefaultConnection": "Data Source=;Initial Catalog=;Persist Security Info=True;User ID=; Password=;"
}

在startup.cs中,按如下所述获取:

public class Startup
{
    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);

        builder.AddEnvironmentVariables();
        Configuration = builder.Build();
    }

    public IConfigurationRoot Configuration { get; }
}

使用依赖注入在控制器中注入配置,如下所述:

public class MyController : Controller
{
    private readonly IConfiguration _configuration;
    private string connectionString;

    public MyController(IConfiguration configuration) 
    {
        _configuration = configuration;

        connectionString = _configuration.GetConnectionString("DefaultConnection");
    }
}