A Secure System Includes _____ That Can Log Every Instance of Data Entry and Changes.

Logging in Entity Framework Cadre

We often need to log the SQL and change tracking data for debugging purposes in EF Core.

EF Core logging automatically integrates with the logging mechanisms of .NET Core. So, learn well-nigh fundamentals of logging in .NET Core before implimenting logging in EF Core.

Entity Framework Core integrates with the .Net Cadre logging to log SQL and modify tracking information to the various output targets. First, install the Nuget package for logging provider of your choice and and so tie up the DbContext to ILoggerFactory.

Let'due south install the logging provider's NuGet package. Hither, we will brandish the logs on the console, so install the Microsoft.Extensions.Logging.Panel NuGet parcel from the NuGet Package Manager or execute the following command in the Package Managing director Console:

PM> Install-Packet Microsoft.Extensions.Logging.Console

The following figure illustrates how the DbContext works with the logging API and panel logging provider.

After installing the console logger provider, yous need to create a static/singleton example of the LoggerFactory and so tie it with a DbContext, as shown below.

          public          form          SchoolContext          :          DbContext          {          //static LoggerFactory object          public          static          readonly          ILoggerFactory loggerFactory =          new          LoggerFactory(new[] {          new          ConsoleLoggerProvider((_, __) =>          truthful,          true)         });          //or          // public static readonly ILoggerFactory loggerFactory  = new LoggerFactory().AddConsole((_,___) => truthful);          public          SchoolContext():base of operations()     {      }          protected          override          void          OnConfiguring(DbContextOptionsBuilder          optionsBuilder)     {         optionsBuilder.UseLoggerFactory(loggerFactory)          //tie-up DbContext with LoggerFactory object          .EnableSensitiveDataLogging()               .UseSqlServer(@"Server=.\SQLEXPRESS;Database=SchoolDB;Trusted_Connection=True;");     }          public          DbSet<Student> Students { get; set; } }        

In the in a higher place example, we have created an object of the LoggerFactory form and assigned it to the ILoggerFactory blazon static variable. And then, we passed this object in the optionsBuilder.UseLoggerFactory() method in the OnConfiguring() method. This volition enable the DbContext to share the information with the loggerFactory object, which in turn will display all the logging information on the console.

By default, EF Cadre volition not log sensitive data, such equally filter parameter values. So, call the EnableSensitiveDataLogging() to log sensitive data.

The EF team recommends using the same logger factory object with all the instances of the DbContext class during the application lifetime. Otherwise, it may upshot in a retention leak and poor performance. Y'all can also create a split factory class that provides y'all the singleton object of the LoggerFactory class to use with the DbContext.

Let's empathize the in a higher place example in detail.

First, we created an object of the LoggerFactory form and assigned it to ILoggerFactory type static variable, as shown below.

          public          static          readonly          ILoggerFactory          loggerFactory =          new          LoggerFactory(          new[] {          new          ConsoleLoggerProvider ((_, __) =>          true,          true) } );        

The LoggerFactory tin can incorporate one or more logging providers which can be used to log to multiple mediums concurrently. The constructor of the LoggerFactory have an array of different logger provider objects every bit new[] { }. We want to display logs on the console, and then create an object of the panel logger provider ConsoleLoggerProvider.

There are 4 constructors of the ConsoleLoggerProvider. Use the one that allows lambda expression (Func<>) for log filtration and includeScope Boolean, as shown below.

          new          ConsoleLoggerProvider((_, __) =>          true,          truthful)        

Hither, nosotros don't desire to filter whatever information and so the lambda expression would always render truthful (_, __) => true.

After creating an object of ILoggerFactory, tied-upwards DbContext with the ILoggerFactory in the OnConfiguring() method using the DbContextOptionsBuilder.

optionsBuilder.UseLoggerFactory(loggerFactory)        

Thus, we tied-up the DbContext with the LoggerFactory which includes the console logger provider. Now, we can encounter all the logs on the console whenever an instance of the DbContext executes any action.

Consider the following example.

          using          (var          context =          new          SchoolContext()) {          var          std =          new          Pupil(){ StudentName =          "Steve"          };     context.Add(std);                      context.SaveChanges();     Panel.ReadLine(); }        

The above example will display the following logs on the console:

dbug: Microsoft.EntityFrameworkCore.Infrastructure[100401]
An 'IServiceProvider' was created for internal employ by Entity Framework.
info: Microsoft.EntityFrameworkCore.Infrastructure[100403]
Entity Framework Core 2.0.0-rtm-26452 initialized 'SchoolContext' using pr
ovider 'Microsoft.EntityFrameworkCore.SqlServer' with options: SensitiveDataLoggingEnabled
dbug: Microsoft.EntityFrameworkCore.Database.Connection[200000]
Opening connectedness to database 'SchoolDB' on server '.\SQLEXPRESS'.

dbug: Microsoft.EntityFrameworkCore.Database.Connection[200001]
Opened connection to database 'SchoolDB' on server '.\SQLEXPRESS'.
dbug: Microsoft.EntityFrameworkCore.Database.Transaction[200200]
Beginning transaction with isolation level 'ReadCommitted'.
warn: Microsoft.EntityFrameworkCore.Database.Command[100400]
Sensitive data logging is enabled. Log entries and exception messages may
include sensitive application data, this mode should merely be enabled during development.
dbug: Microsoft.EntityFrameworkCore.Database.Command[200100]
Executing DbCommand [Parameters=[@p0='' (DbType = DateTime2), @p1='' (DbTy
pe = Int32), @p2='0', @p3='' (Size = 8000) (DbType = Binary), @p4='Steve' (Size = 4000), @p5='0'], CommandType='Text', CommandTimeout='30']
Set NOCOUNT ON;
INSERT INTO [Students] ([DateOfBirth], [GradeId], [Height], [Photo], [Stud
entName], [Weight])
VALUES (@p0, @p1, @p2, @p3, @p4, @p5);
SELECT [StudentID]
FROM [Students]
WHERE @@ROWCOUNT = ane AND [StudentID] = scope_identity();
info: Microsoft.EntityFrameworkCore.Database.Control[200101]
Executed DbCommand (68ms) [Parameters=[@p0='' (DbType = DateTime2), @p1=''
(DbType = Int32), @p2='0', @p3='' (Size = 8000) (DbType = Binary), @p4='Steve'
(Size = 4000), @p5='0'], CommandType='Text', CommandTimeout='thirty']
Gear up NOCOUNT ON;
INSERT INTO [Students] ([DateOfBirth], [GradeId], [Height], [Photo], [Stud
entName], [Weight])
VALUES (@p0, @p1, @p2, @p3, @p4, @p5);
SELECT [StudentID]
FROM [Students]
WHERE @@ROWCOUNT = 1 AND [StudentID] = scope_identity();
dbug: Microsoft.EntityFrameworkCore.Database.Command[200300]
A information reader was disposed.
dbug: Microsoft.EntityFrameworkCore.Database.Transaction[200202]
Committing transaction.
dbug: Microsoft.EntityFrameworkCore.Database.Connection[200002]
Endmost connexion to database 'SchoolDB' on server '.\SQLEXPRESS'.

dbug: Microsoft.EntityFrameworkCore.Database.Connectedness[200003]
Closed connection to database 'SchoolDB' on server '.\SQLEXPRESS'.
dbug: Microsoft.EntityFrameworkCore.Database.Transaction[200204]
Disposing transaction.

As you can see, it logs all the information.

Filter Logs

In the above example, the DbContext logged all the information while saving an entity. Erstwhile you don't want to log all the data and filter some unwanted logs. In EF Core, you can filter logs by specifying the logger category and log level.

Logger Categories

EF Core two.10 includes the DbLoggerCategory class to get an Entity Framework Cadre logger categories using its Name belongings. The post-obit table lists different logger categories.

Logger Category Class	Description
Database.Command	Logger category for command execution, including SQL sent to database.
Database.Connectedness	Logger category for db connection operations.
Database.Transaction	Logger category for db transactions.
Infrastructure	Logger category for miscellaneous messages for the EF infrastructure.
Migration	Logger category for migrations.
Model	Logger category for model edifice and metadata.
Query	Logger category for queries (excluding generated SQL).
Scaffolding	Logger category for scaffolding and reverse engineering.
Update	Logger category for DbContext.SaveChanges() letters.

Log SQL Queries

To log only SQL queries, specify the DbLoggerCategory.Database.Command category and LogLevel.Information in the lambda expression in the constructor of the ConsoleLoggerProvider, every bit shown below.

          public          static          readonly          ILoggerFactory          consoleLoggerFactory               =          new          LoggerFactory(new[] {          new          ConsoleLoggerProvider((category, level) =>                     category ==          DbLoggerCategory.Database.Command.Proper noun &&                     level ==          LogLevel.Information,          true)                 });        

Or, merely telephone call the AddConsole() method on LoggerFactory to log SQL queries, by default.

          public          static          readonly          ILoggerFactory          consoleLoggerFactory          =          new          LoggerFactory().AddConsole();        

Now, this will log the post-obit query information which saving an entity using the DbContext.

info: Microsoft.EntityFrameworkCore.Database.Command[200101]
Executed DbCommand (73ms) [Parameters=[@p0='' (DbType = DateTime2), @p1=''
(DbType = Int32), @p2='0', @p3='' (Size = 8000) (DbType = Binary), @p4='Steve'
(Size = 4000), @p5='0'], CommandType='Text', CommandTimeout='30']
Fix NOCOUNT ON;
INSERT INTO [Students] ([DateOfBirth], [GradeId], [Top], [Photograph], [Stud
entName], [Weight])
VALUES (@p0, @p1, @p2, @p3, @p4, @p5);
SELECT [StudentID]
FROM [Students]
WHERE @@ROWCOUNT = i AND [StudentID] = scope_identity();

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Source: https://www.entityframeworktutorial.net/efcore/logging-in-entityframework-core.aspx