How to use IDbConnection dependency injection and use it in any class?

Question

Hi,

I expect to not open/close every time I need to access a table, I learn about IDbConnection dependency injection for PostgreSQL, I have tried the following:

program.cs

builder.Services.AddSingleton<IDbConnection>((sp) => new NpgsqlConnection(Models.AppSettings.PG_SQL.Connection_String));

and in my test class is:

public class Test
    {
        protected IDbConnection _connection;

        protected Test(IDbConnection connection)
        {
            _connection = connection;
        }

        public static async Task MyTest()
        {
            string sqlCount = "select count(0) from sales";
            long ret = _connection.ExecuteScalar<long>(sqlCount, new { });
        }
    }

I expect to call Test.MyTest() since MyTest is a static method

how to accomplish this?

Answer 1

Hi @winanjaya,

It seems the _connection.ExecuteScalar<long> is your customize extension method. Any way, for how to dependency injection in the static class, you could follow like below:

Program.cs

builder.Services.AddSingleton<IDbConnection>((sp) => new NpgsqlConnection(Models.AppSettings.PG_SQL.Connection_String));
var app = builder.Build();

var connection = app.Services.GetRequiredService<IDbConnection>();
Test.Configure(connection);

Test.cs

public class Test
{
    protected static  IDbConnection _connection;
    public static void Configure(IDbConnection connection)
    {
        _connection = connection;
    }

    public static async Task MyTest()
    {
        //...        
    }
}

Call the static class in the controller action

public class HomeController : Controller
{
    public async Task Index()
    {
        await Test.MyTest();      
    }
}

If there has any problem, please let me know freely.

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