网络核心连接字符串Dapper Visual Studio 2017

本文介绍了网络核心连接字符串Dapper Visual Studio 2017的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我试图在.Net Core应用程序中设置连接字符串，但我不断收到错误消息：

I am trying to get a Connection String set up in my .Net Core application but i keep getting the error:

System.NullReferenceException：'Object引用未设置为对象的实例。'

我尝试将以下内容添加到 appsettings.json 中：

I have tried adding the following to appsettings.json:

"ConnectionStrings": { "Analysis": "Server=DESKTOP-MYSERVER;Database=MYDATABASE;User Id=sa; Password=Password123;Provider=System.Data.SqlClient;Trusted_Connection=True;MultipleActiveResultSets=true;Pooling=false;" }

我也尝试过使用 Core之前的web.config：

I also tried using web.config like I used to before .Net Core:

<connectionStrings> <add name="Analysis" providerName="System.Data.SqlClient" connectionString="Server=DESKTOP-MYSERVER;Database=MYDATABASE;User Id=sm;Password=Password123;"/>

然后在C＃中我有：

public List<DapperTest> ReadAll() { var data = new List<DapperTest>(); using (IDbConnection db = new SqlConnection(ConfigurationManager.ConnectionStrings["Analysis"].ConnectionString)) { data = db.Query<DapperTest>("select * from testTable").ToList(); } return data; }

两种方式都给我以下例外：

Both ways give me the exception of:

System.NullReferenceException：'对象引用未设置为对象的实例。'

我使用了以下资源：

.Net CORE Dapper连接字符串吗？

docs.microsoft/zh-cn/aspnet/core/data/ef-mvc/intro

从App.config获取连接字符串

但是我错过了一些东西。我只设置了一次连接字符串，但它不在.Net Core中，因此对其他人来说很明显。

But I am missing something. I have only set up connection strings once and it was not in .Net Core so it could be obvious to others.

推荐答案

如果使用的是appsettings.json，请创建一个简单的POCO类来对连接字符串配置进行建模，如下所示：

If you are using appsettings.json, create a simple POCO class to model your connection string configurations like this:

public class ConnectionConfig { public string Analysis {get;set;} }

在Startup.cs的ConfigureServices方法中添加此行

Add this line in ConfigureServices method in Startup.cs

services.Configure<ConnectionConfig>(Configuration.GetSection("ConnectionStrings"));

数据服务等级

class YourClass{ private string _connectionString; YourClass(string connectionString){ _connectionString = connectionString; } //Your implementation public List<DapperTest> ReadAll() { var data = new List<DapperTest>(); using (IDbConnection db = new SqlConnection(_connectionString) { data = db.Query<DapperTest>("select * from testTable").ToList(); } return data; } }

注入 IOptions< ConnectionConfig> 在您的控制器构造函数中。

Inject IOptions<ConnectionConfig> in your controller constructor .

class YourController : Controller{ YourClass _testing; YourController(IOptions<ConnectionConfig> connectionConfig){ var connection = connectionConfig.Value; string connectionString = connection.Analysis; _testing = new YourClass(connectionString ); } public IActionResult Index() { var testingData = _testing.ReadAll(); return View(); } }