WEB API CORE WITH ADO.NET connectionstring issue

I am new to web api core,I have created one web api core with ado.net application.
I have declared a conenction string in appseeting.json,
I am trying new access in the controller but i am getting null value?
can any one help me how to access conenction string in controller from appsetting.sjon
"Logging": {

"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"

"AllowedHosts": "*",
"ConnectionStrings": {
"DefaultConnection": "Server=(localdb)\\MSSQLLOCALDB;Database=resource;Trusted_Connection=True;"


step 2
SqlConnection con1 = new SqlConnection(configuration.GetConnectionString("DefaultConnection"));