Unable to read connection string from appsettings.json in a console application

Question

I was tring .NET core with a console application and I'm stucked on reading from appsettings.json. Here's my code:

{
    "ConnectionStrings": {
        "DataBaseConnectionString": "Server=xxxxxx"
        }
}

...

var builder = new ConfigurationBuilder()
    //  .SetBasePath("")
    .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
    .AddEnvironmentVariables();
configuration = builder.Build();

var xx = configuration.GetConnectionString("DataBaseConnectionString");

I got null on xx, what am I doing wrong? Thanks

If someone is also getting System.InvalidOperationException: The ConnectionString property has not been initialized error do this: right click on appsettings.json -> Properties -> Set Copy to output directory to Copy always — Nika Nabakhteveli
– Nika Nabakhteveli, Commented Mar 27, 2023 at 19:39

Ilya Chumakov · Accepted Answer · 2017-05-03 05:01:07Z

8

Your code is correct. Set optional: false to check the file exists. The keypoint for a console app is to ensure appsettings.json has Copy to output directory: Always property.

Here is a minimal reproducible example:

//set "optional: false" to fail-fast without a file
var builder = new ConfigurationBuilder().AddJsonFile("appsettings.json", optional: false);
var configuration = builder.Build();

//contains "Server=xxxxxx"
string str = configuration.GetConnectionString("DataBaseConnectionString");

Actual documentation: Configuration in ASP.NET Core

edited May 3, 2017 at 5:01

answered May 2, 2017 at 15:32

Ilya Chumakov

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