Implementing Missing Features in Entity Framework Core – Part 8: Logging to the Console
This is the eight post in a series of posts about bringing the features that were present in Entity Framework pre-Core into EF Core. The others are:
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Part 1: Introduction, Find, Getting an Entity’s Id Programmatically, Reload, Local, Evict
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Part 2: Explicit Loading
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Part 3: Validations
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Part 4: Conventions
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Part 5: Getting the SQL for a Query
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Part 6: Lazy Loading
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Part 7: Entity Configuration in Mapping Classes
This time I’m going to talk about the possibility to log the generated SQL to the output. In the past, we could do it by assigning a writer to DbContext.Database.Log:
ctx.Database.Log = Console.Log;
This would cause all SQL statements to be sent to the
console. We can do something similar in EF Core, by
leveraging the logging framework:
var loggerFactory = new LoggerFactory()
.AddDebug((categoryName, logLevel) => (logLevel == LogLevel.Information) && (categoryName == DbLoggerCategory.Database.Command.Name))
.AddConsole((categoryName, logLevel) => (logLevel == LogLevel.Information) && (categoryName == DbLoggerCategory.Database.Command.Name));
var optionsBuilder = new DbContextOptionsBuilder<MyContext>()
.UseLoggerFactory(loggerFactory)
.UseSqlServer(@"<connectionString>");
var ctx = new MyContext(optionsBuilder.Options);
We are creating a new logger factory and populating it with
the console and debug providers. You will need to add the
Microsoft.Extensions.Logging.Console
and
Microsoft.Extensions.Logging.Debug
NuGet packages (you don’t need both). For each of these
providers, we are filtering the output by
LogLevel.Information
and category
DbLoggerCategory.Database.Command.Name
(“Microsoft.EntityFrameworkCore.Database.Command”), which
are the values used when outputting SQL.
Then, we are creating a DbContextOptionsBuilder and in it we are replacing the default logger factory with our own. We then use it to create an option which we pass to our DbContext’s constructor, or we could do the same in the OnConfiguring method.
The output will look something like this:
SELECT [p].[ProjectId], [p].[CreatedAt], [p].[CreatedBy], [p].[CustomerId], [p].[Description], [p].[End], [p].[Name], [p].[Start], [p].[UpdatedAt], [p].[UpdatedBy]Hope this helps!
FROM [Projects] AS [p]
