How to View the SQL Generated by Entity Framework Core using .NET Core Logging

Today I'm going to show you how to intercept and view the SQL generated by Entity Framework Core. This method takes advantage of Microsoft's built in logging for .NET core.

H/T to Julie Lerman for this over in https://thedatafarm.com/ . I learned about this method using her Pluralslight course here

This is something I wish I knew about starting off. I hope it is of use to somebody else.

This method is an alternative to profiling the SQL using something like SQL Server Management Studio. This will work with an ASP.NET Core application which should cover the vast majority of use cases!

By default, .NET core outputs logs to the following locations when you call HostCreateDefaultBuilder(args) within Program.cs:

Console
Debug
Event Source
EventLog (Windows Only)

Logging in .NET Core and ASP.NET Core

Learn how to use the logging framework provided by the Microsoft.Extensions.Logging NuGet package.

Rick-AndersonMicrosoft Docs

Default providers for logging in .Net Core

Default Logging providers for ASP.NET Core application as of 14 May 2020

1. Enable Sensitive Data Logging

Navigate to your startup file for your .NET Core project (Startup.cs). Now find where you've configured your application to use Entity Framework Core. This should be in the ConfigureServices method.

My ConfigureServices method before enabling sensitive data logging

Enable sensitive data logging by calling the EnableSensitiveDataLogging method.

 services.AddDbContext<DutchContext>(
                cfg =>
                {
                    cfg.UseSqlServer(_config.GetConnectionString("DutchConnectionString")).EnableSensitiveDataLogging();
                }
                );

My ConfigureServices method after enabling sensitive data logging

Enabling Sensitive Data Logging allows you to view the parameters being passed into the SQL Queries in the logs.

2. Configure the Logging

The next step is to tell your ASP.NET Core App to log Entity Framework Core commands.

For this step, go to your config file. Typically this is named 'Appsettings.json'. It's likely you configured the connection string for your application here.

This is what mine looks like:

Configuration file for my application before configuring the logging for Entity Framework Core Database commands.

Add a new line to "Logging" .=> "LogLevel"

"Microsoft.EntityFrameworkCore.Database.Command": "Information"

The logging config should now look something like this:

"Logging": {
		"LogLevel": {
			"Default": "Information",
			"Microsoft": "Warning",
			"Microsoft.EntityFrameworkCore.Database.Command": "Information"
		}
	}

My final configuration file: