Logging to Console

[ErikEJ]

Is SQL statement logging to console available in the current api, and if yes, do yiu have a sample?

[rowanmiller]

Hey Erik,

It's not very pretty yet... but here is a way to wire up the low level pieces to make it happen.

Compiled and tested on Beta 6... may need tweaks for latest dev code base.

using Microsoft.Data.Entity;
using Microsoft.Data.Entity.Infrastructure;
using Microsoft.Framework.Logging;
using System;
using System.IO;
using System.Linq;

namespace EFGetStarted.ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            using (var db = new BloggingContext())
            {
                db.Database.EnsureCreated();

                db.Blogs.Add(new Blog { Url = "http://blogs.msdn.com/adonet" });
                db.SaveChanges();

                db.Blogs.ToList();
            }
        }
    }

    public class BloggingContext : DbContext
    {
        public BloggingContext()
        {
            var loggerFactory = ((IAccessor<IServiceProvider>)this).GetService<ILoggerFactory>();
            loggerFactory.AddProvider(new DbLoggerProvider());
        }

        public DbSet<Blog> Blogs { get; set; }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer(@"Server=(localdb)\mssqllocaldb;Database=LoggingDemo;Trusted_Connection=True;");
        }
    }

    public class Blog
    {
        public int BlogId { get; set; }
        public string Url { get; set; }
    }

    public class DbLoggerProvider : ILoggerProvider
    {
        private static readonly string[] _whitelist = new string[]
        {
                typeof(Microsoft.Data.Entity.Update.BatchExecutor).FullName,
                typeof(Microsoft.Data.Entity.Query.QueryContextFactory).FullName
        };

        public ILogger CreateLogger(string name)
        {
            if (_whitelist.Contains(name))
            {
                return new DbLogger();
            }

            return NullLogger.Instance;
        }
    }

    public class DbLogger : ILogger
    {
        public void Log(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter)
        {
            var message = $"{Environment.NewLine}{formatter(state, exception)}";
            File.AppendAllText(@"C:\temp\DatabaseLog.sql", message);
        }

        public bool IsEnabled(LogLevel logLevel)
        {
            return true;
        }

        public IDisposable BeginScopeImpl(object state)
        {
            return null;
        }
    }

    public class NullLogger : ILogger
    {
        private static NullLogger _instance = new NullLogger();

        public static NullLogger Instance
        {
            get { return _instance; }
        }

        public void Log(LogLevel logLevel, int eventId, object state, Exception exception, Func<object, Exception, string> formatter)
        { }

        public bool IsEnabled(LogLevel logLevel)
        {
            return false;
        }

        public IDisposable BeginScopeImpl(object state)
        {
            return null;
        }
    }

}

[rowanmiller]

BTW here is the work item to add something like Database.Log that we had in the past #1199

[ErikEJ]

@rowanmiller Thanks, not exactly intuitive! It will come in very handy for a demo with the SQLCE provider (as no Profiler is available with that)

[ErikEJ]

Thanks, added that to my providers (for the time being) as a LogToConsole() extension method on the DbContext