我试图在我的.Net Core应用程序中设置连接字符串,但我一直收到错误：
System.NullReferenceException：’对象引用未设置为对象的实例.’
"ConnectionStrings": {
"Analysis": "Server=DESKTOP-MYSERVER;Database=MYDATABASE;User Id=sa; Password=Password123;Provider=System.Data.sqlClient;Trusted_Connection=True;MultipleActiveResultSets=true;Pooling=false;"
}
我也试过像以前那样使用web.config .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#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;
}
两种方式都给我例外：
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 Connection String?
https://docs.microsoft.com/en-us/aspnet/core/data/ef-mvc/intro
Get connection string from App.config
但我错过了一些东西.我只设置了一次连接字符串,它不在.Net Core中,因此对其他人来说显而易见.
解决方法
如果您正在使用appsettings.json,请创建一个简单的POCO类来为您的连接字符串配置建模,如下所示：
public class ConnectionConfig
{
public string Analysis {get;set;}
}
在Startup.cs中的ConfigureServices方法中添加此行
services.Configure<ConnectionConfig>(Configuration.GetSection("ConnectionStrings"));
数据服务类
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>在你的控制器构造函数中.
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();
}
}
