ZNetCS.AspNetCore.Logging.EntityFrameworkCore

This is Entity Framework Core logger and logger provider. A small package to allow store logs in any data store using Entity Framework Core. It was prepared to use in ASP NET Core application, but it does not contain any references that prevents to use it in plain .NET Core application.

Installing

Install using the ZNetCS.AspNetCore.Logging.EntityFrameworkCore NuGet package

PM> Install-Package ZNetCS.AspNetCore.Logging.EntityFrameworkCore

Usage

When you install the package, it should be added to your .csproj. Alternatively, you can add it directly by adding:

<ItemGroup>
    <PackageReference Include="ZNetCS.AspNetCore.Logging.EntityFrameworkCore" Version="2.1.0" />
</ItemGroup>

As from ASP.NET Core 2.0 version, the configuration of logging was changed. Now it should be configure with WebHostBuilder See: Introduction to logging in ASP.NET Core for more details.

As from version 2.0.2 there is silent error handling on logger SaveChanges(). To avoid Db error having impact on application.

using ZNetCS.AspNetCore.Logging.EntityFrameworkCore;

...

public static void Main(string[] args)
{
    var webHost = new WebHostBuilder()
        // other code ommited to focus on logging settings
        .ConfigureLogging((hostingContext, logging) =>
        {
            // other log providers
            // ...
            //
            logging.AddEntityFramework<MyDbContent>();

        })
        .UseStartup<Startup>()
        .Build();

    webHost.Run();
}

Important Notes

In most case scenario you would not like add all logs from application to database. A lot of of them is jut debug/trace ones. In that case is better use filter before add Logger. This will also prevent some StackOverflowException when using this logger to log EntityFrameworkCore logs.

public static void Main(string[] args)
{
    var webHost = new WebHostBuilder()
        // other code ommited to focus on logging settings
        .ConfigureLogging((hostingContext, logging) =>
        {
            // other log providers
            // ...
            //

            // because setting up filter inside code requires exact provider class, and EntityFrameworkLoggerProvider is generic class with multiple overrides
            // filters needs to applied properly to chosen provider
            logging.AddFilter<EntityFrameworkLoggerProvider<MyDbContent>>("Microsoft", LogLevel.None);
            logging.AddFilter<EntityFrameworkLoggerProvider<MyDbContent>>("System", LogLevel.None);
            logging.AddEntityFramework<MyDbContent>();

        })
        .UseStartup<Startup>()
        .Build();

    webHost.Run();
}

It is also possible to setting filters inside appsettings.json file. This provider is using EntityFramework alias. This way is recommended because there is no need to care about proper provider definition.

{
  "Logging": {
    "EntityFramework": {
      "LogLevel": {
        "Microsoft": "None",
        "System": "None"
      }
    }
  }
}

public static void Main(string[] args)
{
    var webHost = new WebHostBuilder()
        // other code ommited to focus on logging settings
        .ConfigureLogging((hostingContext, logging) =>
        {
            logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));

            // other log providers
            // ...
            //

            logging.AddEntityFramework<MyDbContent>();

        })
        .UseStartup<Startup>()
        .Build();

    webHost.Run();
}

Then you need to setup your context to have access to log table e.g.

using ZNetCS.AspNetCore.Logging.EntityFrameworkCore;

public class MyDbContext : DbContext
{
    public MyDbContext(DbContextOptions options) : base(options)
    {
    }
   
    public DbSet<Log> Logs { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        base.OnModelCreating(modelBuilder);

        // build default model.
        LogModelBuilderHelper.Build(modelBuilder.Entity<Log>());

        // real relation database can map table:
        modelBuilder.Entity<Log>().ToTable("Log");
    }   
}

There is also possibilty to extend base Log class.

public class ExtendedLog : Log
{
    public ExtendedLog(IHttpContextAccessor accessor)
    {          
        string browser = accessor.HttpContext.Request.Headers["User-Agent"];
        if (!string.IsNullOrEmpty(browser) && (browser.Length > 255))
        {
            browser = browser.Substring(0, 255);
        }

        this.Browser = browser;
        this.Host = accessor.HttpContext.Connection?.RemoteIpAddress?.ToString();
        this.User = accessor.HttpContext.User?.Identity?.Name;
        this.Path = accessor.HttpContext.Request.Path;
    }

    protected ExtendedLog()
    {
    }
      
    public string Browser { get; set; }
    public string Host { get; set; }
    public string Path { get; set; }
    public string User { get; set; }
}

Change MyDbContext to use new extended log model

public DbSet<ExtendedLog> Logs { get; set; }

You can extend ModelBuilder as well:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    // build default model.
    LogModelBuilderHelper.Build(modelBuilder.Entity<ExtendedLog>());

    // real relation database can map table:
    modelBuilder.Entity<ExtendedLog>().ToTable("Log");

    modelBuilder.Entity<ExtendedLog>().Property(r => r.Id).ValueGeneratedOnAdd();

    modelBuilder.Entity<ExtendedLog>().HasIndex(r => r.TimeStamp).HasName("IX_Log_TimeStamp");
    modelBuilder.Entity<ExtendedLog>().HasIndex(r => r.EventId).HasName("IX_Log_EventId");
    modelBuilder.Entity<ExtendedLog>().HasIndex(r => r.Level).HasName("IX_Log_Level");

    modelBuilder.Entity<ExtendedLog>().Property(u => u.Name).HasMaxLength(255);
    modelBuilder.Entity<ExtendedLog>().Property(u => u.Browser).HasMaxLength(255);
    modelBuilder.Entity<ExtendedLog>().Property(u => u.User).HasMaxLength(255);
    modelBuilder.Entity<ExtendedLog>().Property(u => u.Host).HasMaxLength(255);
    modelBuilder.Entity<ExtendedLog>().Property(u => u.Path).HasMaxLength(255);
}   

To use IHttpContextAccessor there is need to register it inside ConfigureServices call of Startup:

public void ConfigureServices(IServiceCollection services)
{
    // requires for http context access.
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

Add extended log registration

public static void Main(string[] args)
{
    var webHost = new WebHostBuilder()
        // other code ommited to focus on logging settings
        .ConfigureLogging((hostingContext, logging) =>
        {
            logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));

            // other log providers
            // ...
            //

            logging.AddEntityFramework<MyDbContent, ExtendedLog>();

        })
        .UseStartup<Startup>()
        .Build();

    webHost.Run();
}

There is also possibility to create new log model using custom creator method. This can be done by providing options during configuration.

public static void Main(string[] args)
{
    var webHost = new WebHostBuilder()
        // other code ommited to focus on logging settings
        .ConfigureLogging((hostingContext, logging) =>
        {
            logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));

            // other log providers
            // ...
            //

            logging.AddEntityFramework<MyDbContent>(
                opts =>
                {
                    opts.Creator = (logLevel, eventId, name, message) => new Log
                    {
                        TimeStamp = DateTimeOffset.Now,
                        Level = logLevel,
                        EventId = eventId,
                        Name = "This is my custom log",
                        Message = message
                    };
                });

        })
        .UseStartup<Startup>()
        .Build();

    webHost.Run();
}

Below configuration is still compatible with 2.0, but currently recommended way to configure logging is to use Web Host Builder.

In order to use the Entity Framework Logger Provider, you must configure the logger factory in Configure call of Startup:

using ZNetCS.AspNetCore.Logging.EntityFrameworkCore;

...

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    // MyDbContext is registered in ConfigureServices Entity Framework Core application context
    loggerFactory.AddEntityFramework<MyDbContent>(app.ApplicationServices);

    // other middleware e.g. MVC etc
}

For filtering with ILoggerFactory there is required to install Microsoft.Extensions.Logging.Filter package (which is now deprecated).

PM> Install-Package  Microsoft.Extensions.Logging.Filter;

    loggerFactory
        .WithFilter(
            new FilterLoggerSettings
            {
                { "Microsoft", LogLevel.None },
                { "System", LogLevel.None }
            })
        .AddEntityFramework<MyDbContent>(app.ApplicationServices);

For using extended logging change in Configure call of Startup:

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    // MyDbContext is registered in ConfigureServices Entity Framework Core application context
    loggerFactory.AddEntityFramework<MyDbContext, ExtendedLog>(app.ApplicationServices);

    // other middleware e.g. MVC etc
}

Usage of ustom creator method (without resolving dependencies). This can be done by extending loggerFactory.AddEntityFramework call.

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    // MyDbContext is registered in ConfigureServices Entity Framework Core application context
    loggerFactory 
        .AddEntityFramework<MyDbContext>(
            app.ApplicationServices,
            creator: (logLevel, eventId, name, message) => new Log
            {
                TimeStamp = DateTimeOffset.Now,
                Level = logLevel,
                EventId = eventId,
                Name = "This is my custom log",
                Message = message
            });

    // other middleware e.g. MVC etc
}