在 ASP.net Core 2 MVC 应用程序中从 appSettings.json 存储/检索 ConnectionString [英] Store / Retrieve ConnectionString from appSettings.json in ASP.net Core 2 MVC app

问题描述

我正在寻找将连接字符串存储在 .net Core 2 MVC 应用程序中的 appsettings.json 中的最佳实践方法(就像您在 MVC 5 中的 web.config 中所做的那样).

I'm looking for the best practice way to store a connection string in appsettings.json in a .net Core 2 MVC app (like you do in web.config in MVC 5).

我想使用 Dapper 而不是 EF(我发现了很多 EF 示例).

I want to use Dapper not EF (I found many EF examples).

像这样:

{
  "ConnectionStrings": {
    "myDatabase": "Server=.;Database=myDatabase;Trusted_Connection=true;"
  },

  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Warning"
    }
  }
}

网上肯定有很多例子吗?我找不到任何适用于 .net core 2.0 的东西.

Surely there are many examples online? Nothing I can find that is for .net core 2.0.

在 1 和 2 之间发生了一些变化，我想确保我使用的是版本 2 的最佳实践.

Several things have changed between 1 and 2 and I want to ensure I'm using version 2 best practices.

我发现了这个 - 但它似乎是 .net core 1:Visual Studio 2017 - MVC 核心 - 第 05 部分 - 来自 appsettings.json 的连接字符串

I've found this - but it seems to be .net core 1: Visual Studio 2017 - MVC Core - Part 05 - Connection String from appsettings.json

这使用键值对 appsettings - 而不是连接字符串:在 ASP.NET Core 2.0 中读取 AppSettings

This uses key value pair appsettings - not the connectionstrings: Read AppSettings in ASP.NET Core 2.0

同样不清楚这是 .net Core 1 还是 2:Net Core Connection String Dapper Visual Studio 2017

Again it's unclear if this is .net Core 1 or 2: Net Core Connection String Dapper visual studio 2017

推荐答案

在 appsettings.json

中定义您的连接字符串

Define your connection string(s) in appsettings.json

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

在启动时读取其值

如果您遵循约定并在connectionStrings 下定义连接字符串，则可以使用扩展方法GetConnectionString() 读取其值.

Read its value on Startup

If you follow the convention and define your connection string(s) under connectionStrings, you can use the extension method GetConnectionString() to read its value.

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?

您可以使用选项模式.

1. 定义一个与 appsettings.json 中的 JSON 对象结构完全匹配的类

1. Define a class that exactly matches the JSON object structure in appsettings.json

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

在启动时注册该配置

Register that configuration on Startup

public void ConfigureServices(IServiceCollection services)
{
   // ...

   services.Configure<ConnectionStringConfig>(
       this.Configuration.GetSection("connectionStrings")
   );

   // ...
}

在您的 POCO 中接收访问器

Receive the accessor in your POCO

public class YourPoco
{
    private readonly ConnectionStringConfig _connectionStringConfig;

    public YourPoco(IOptions<ConnectionStringConfig> configAccessor)
    {
        _connectionStringConfig = configAccessor.Value;

        // Your connection string value is here:
        // _connectionStringConfig.AppDbConnection;
    }
}

注意事项:

1. 请参阅我的示例代码，了解如何在 Core 1.x 和 2.0 上从 appsettings.json 读取值.
2. 如果您有 1 个以上的连接字符串，请参阅如何设置.

1. See my sample codes on how to read values from appsettings.json both on Core 1.x and 2.0.
2. See how I setup if you have more than 1 connection string.

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