如何向 ASP.Net Core Logging 提供额外参数答案

【问题标题】：How to provide to ASP.Net Core Logging extra parameters如何向 ASP.Net Core Logging 提供额外参数
【发布时间】：2017-01-10 17:34:07
【问题描述】：

我正在关注this 示例来自定义核心日志记录以将我的日志保存到数据库。我得到了大部分工作，但只有一个问题：我需要在 DBLogger 类中以干净的方式传递更多参数。它目前有这个签名：

public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)

我希望能够包含一些其他字段。我想我可以将它们添加到由管道分隔的“状态”字段中以供以后分解，但是这种方式看起来很难看。

这里是代码的主要部分：

// DBLoggerExtensions
public static class DBLoggerExtensions
{
    public static ILoggerFactory AddContext(
        this ILoggerFactory factory,
        Func<string, LogLevel, bool> filter = null
        )
    {
        factory.AddProvider(new DBLoggerProvider(filter));
        return factory;
    }

    public static ILoggerFactory AddContext(this ILoggerFactory factory, LogLevel minLevel)
    {
        return AddContext(
            factory,
            (_, logLevel) => logLevel >= minLevel);
    }
}

//LoggerProvider
public class DBLoggerProvider : ILoggerProvider 
{ 
    private readonly Func<string, LogLevel, bool> _filter; 

    public DBLoggerProvider(Func<string, LogLevel, bool> filter) 
    { 
        _filter = filter; 
    } 
    public ILogger CreateLogger(string categoryName) 
    { 
        return new DBLogger(categoryName, _filter); 
    } 

    public void Dispose() 
    { 

    } 
} 
//DBLogger:
public class DBLogger : ILogger 
{ 
    private string _categoryName; 
    private Func<string, LogLevel, bool> _filter; 
    private CustomLoggerDBContext _context; 
    private bool _selfException = false; 

    public DBLogger(string categoryName, Func<string, LogLevel, bool> filter) 
    { 
        _categoryName = categoryName; 
        _filter = filter; 
        _context = new CustomLoggerDBContext(); 
    } 

    public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter) 
    { 
        if (!IsEnabled(logLevel)) 
        { 
            return; 
        } 
        if (_selfException) 
        { 
            _selfException = false; 
            return; 
        } 
        _selfException = true; 
        if (formatter == null) 
        { 
            throw new ArgumentNullException(nameof(formatter)); 
        } 
        var message = formatter(state, exception); 
        if (string.IsNullOrEmpty(message)) 
        { 
            return; 
        } 

        if (exception != null) 
        { 
            message += "\n"+ exception.ToString(); 
        } 
        try 
        { 
            message = message.Length > CustomLoggerDBContext.MessageMaxLength ? 
                message.Substring(0,CustomLoggerDBContext.MessageMaxLength):message; 
            _context.EventLog.Add(new EventLog { 
                Message = message, 
                EventId = eventId.Id, 
                LogLevel = logLevel.ToString(), 
                CreatedTime = DateTime.UtcNow }); 
            _context.SaveChanges(); 
            _selfException = false; 
        } 
        catch { } 
    } 

    public bool IsEnabled(LogLevel logLevel) 
    { 
        return (_filter == null || _filter(_categoryName, logLevel)); 
    } 

    public IDisposable BeginScope<TState>(TState state) 
    { 
        return null; 
    } 
}

欣赏它。

【问题讨论】：

你找到解决办法了吗？
提供的链接无效！

标签： c# asp.net asp.net-core error-logging

【解决方案1】：

你没有得到这些参数。它们用于格式化。见格式中添加参数的例子

var usuario = "marcelo";
var endereco = "Rua A, número 123";
logger.LogInformation("Erro: Usuario: {usuario}, Enderço: {Endereco}", usuario, endereco);
//Func<TState, Exception, string> formatter => "Erro: Usuario: marcelo, Enderço: Rua A, número 123"

【讨论】：