connection string issue in web api core with ado.net

Since you are a beginner. its a good start with understanding the interface IConfiguration. However, I would recommend to explore the Options pattern - there are multiple ways to ready the AppSettings.json. 

https://learn.microsoft.com/en-us/dotnet/core/extensions/options

Please try adding IConfiguration interface into your controller and try the same

It looks like you're on the right track, but there's a missing piece in your code that's causing the null value. You need to inject the IConfiguration interface into your controller so that you can access the connection string from appsettings.json.

Hello Hari,

Can you please check on your startup.cs file have you registered the configuration, if not then can you please add and try after that.

services.AddSinglton(configuration);

then after you can inject the IConfiguration into your API controller

private readonly IConfiguration _configuration;

public ValuesController(IConfiguration configuration)

{

        _configration = configuration;

}

[HttpGet]

public IActionResult Get()

{

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

        .......

}

In ASP.NET Core, inject IConfiguration into your controller's constructor. Use _configuration.GetConnectionString("DefaultConnection") to access the connection string from appsettings.json. This allows you to create a SqlConnection instance for database operations within your controller methods. Ensure namespaces, class names, and methods match your codebase.

using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using System.Data.SqlClient;

namespace Demo.API.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    public class HomeController : ControllerBase
    {
        private readonly IConfiguration _configuration;

        public HomeController(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        [HttpGet]
        public IActionResult Index()
        {
            string connectionString = _configuration.GetConnectionString("DefaultConnection");

            // Use the connection string as needed...
            using (SqlConnection connection = new SqlConnection(connectionString))
            {
                // Your SQL operations here...
                // Example: connection.Open();, execute queries, etc.
            }

            return Ok("Connection successful.");
        }
    }
}

Try this

public class YourController : ControllerBase
{
    private readonly IConfiguration _configuration;
    public YourController(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    [HttpGet]
    public IActionResult Get()
    {
        string dbConnection = _configuration.GetSection("ConnectionStrings").GetSection("DefaultConnection").Value;
        SqlConnection sqlConnection = new SqlConnection(dbConnection);


        return NotFound();
    }
}

Hi 

Try this way.

string connStr = configuration.GetConnectionString("DefaultConnection");  
SqlConnection con1 = new SqlConnection(connStr);