Trace

This page contains the recommended way of implementing a trace object that is injectable to the repositories.

Implementation

Create an interface that implements the ITrace. This is also to support the dependency injection.

public interface INorthwindTrace : ITrace
{
    ...
}

Then, create a class that implements the custom interface.

public class NorthwindTrace : INorthwindTrace
{
    public void AfterQuery(TraceLog log)
    {
        Console.WriteLine(log.Statement);
    }

    public void BeforeQuery(CancellableTraceLog log)
    {
        Console.WriteLine(log.Statement);
    }

    ...
}

Implement all the ITrace methods manually.

Factory

Create a trace factory class.

public static class TraceFactory
{
    private static object _syncLock = new object();
    private static ITrace _trace = null;
    
    public static ITrace CreateTracer()
    {
        if (_trace == null)
        {
            lock (_syncLock)
            {
                if (_trace == null)
                {
                    _trace = new NorthwindTrace();
                }
            }
        }
        return _trace;
    }
}

And pass it in the repository constructor.

public class NorthwindRepository : DbRepository<SqlConnection>
{
    public NorthwindRepository(IOptions<AppSettings> settings)
        : base(settings.Value.ConnectionString, TraceFactory.CreateTracer())
    { }

    ...
}

Dependency Injection

Or inject it as a singleton object.

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();

    // Registration
    services.AddSingleton<INorthwindTrace, NorthwindTrace>();
}

And inject it in the repository constructor.

public class NorthwindRepository : DbRepository<SqlConnection>
{
    public NorthwindRepository(IOptions<AppSettings> settings,
        INorthwindTrace trace)
        : base(settings.Value.ConnectionString, trace)
    { }

    ...
}