如何将ILogger注入EFCore DbContext

Question

我有带有 EFCore 数据库上下文的 .net core 应用程序：

public class MyappDbContext : DbContext
{
    private ILogger<MyappDbContext> _logger;

    public MyappDbContext(DbContextOptions<MyappDbContext> options)
        : base(options)
    {
        // ???
    }
}

在启动类中我注册了上下文：

services.AddDbContext<MyappDbContext>(options => options.UseSqlServer(connectionString));

如何注入

MyappDbContext

、

ILogger

或

ILoggerFactory

（创建记录器）？

Answer 1

您需要做的就是向上下文构造函数添加

ILoggerFactory

或

ILogger

参数：

public class MyappDbContext : DbContext
{
    private readonly ILogger<MyappDbContext> _logger;

    public MyappDbContext(DbContextOptions<MyappDbContext> options,
        ILogger<MyappDbContext> logger)
        : base(options)
    {
        _logger = logger;
    }
}

Answer 2

如果您需要手动实例化 dbcontext：

public class Startup
{
    public static readonly ILoggerFactory logFactory = LoggerFactory.Create(builder => builder.AddDebug());

    ....

    public Startup(IWebHostEnvironment env)
    {
        ....
    }
    public void ConfigureServices(IServiceCollection services)
    {
        ....
    }
}

public class MyDbContext : DbContext
{
    private readonly ILoggerFactory _loggerFactory;

    public MyDbContext(DbContextOptions<MyDbContext> options,
        ILoggerFactory loggerFactory)
        : base(options)
    {
        _loggerFactory = loggerFactory;
    }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseLoggerFactory(_loggerFactory);
        // optionsBuilder.EnableSensitiveDataLogging();
    }
}

// Somewhere else

var db = new MyDbContext(new DbContextOptions<MyDbContext>(), Startup.logFactory);

但我建议使用 DI 代替：

public void ConfigureServices(IServiceCollection services)
{
            services.AddDbContext<MyDbContext>(options =>
                options.UseSqlServer(Configuration.GetConnectionString("Default")).UseLoggerFactory(logFactory));
}

Answer 3

在 DbContextOptionsBuilder 方法的注释中。UseLoggerFactory 说：

使用其中之一时无需调用此方法 “AddDbContext”方法，包括“AddDbContextPool”。

MSDN 参考