实体框架日志记录在异常时不起作用

Question

我已经根据此处的指南实现了实体框架日志记录。但是，它仅在没有异常时记录!!我通过分配超过允许的字符来创建system.FormatException: Input string was not in a correct format.。我的代码是：

Databasecontext context=new DatabaseContext();
TableCity tbCity;
var logger = new MyLogger();           
context.Database.Log = l => logger.Log("Table-tableNews", l);
tbCity.City ="sdkjfaksdjfsdjfjasdfjsdjfjdfjdjfjasdfjlasdjfljdfjdadsfdf";//varchar(25) in dbase
.......... //code removed for clarity
context.TableName.Add(tbCity);
try{
   context.SaveChanges();
 }
 catch(Exception ex)
 {}

我的日志方法

 public void Log(string component, string messages)
 {
    //contents here, which works as desired
 }

我是否需要以不同的方式实现来记录异常？

Answer 1

如果您向下

滚动您提到的链接，您会遇到IDbCommandInterceptor界面。它的功能更加丰富，可以判断查询是成功执行还是失败。

一个示例实现可以是：

public class LogDbCommandInterceptor : IDbCommandInterceptor
{
    public void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        interceptionContext.SetUserState("start", DateTime.Now);
    }
    public void NonQueryExecuted(DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        Console.WriteLine($"sql command: {command.CommandText}, hasFailed: {HasFailed(interceptionContext)}, duration: {CalculateDuration(interceptionContext)}");
        Console.WriteLine($"parameters: {FormatParams(command.Parameters)}, exception: {interceptionContext.Exception?.Message}");
    }
    public void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        interceptionContext.SetUserState("start", DateTime.Now);
    }
    public void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        Console.WriteLine($"sql command: {command.CommandText}, hasFailed: {HasFailed(interceptionContext)}, duration: {CalculateDuration(interceptionContext)}");
    }
    public void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        interceptionContext.SetUserState("start", DateTime.Now);
    }
    public void ScalarExecuted(DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        Console.WriteLine($"sql command: {command.CommandText}, hasFailed: {HasFailed(interceptionContext)}, duration: {CalculateDuration(interceptionContext)}");
    }
    private static double CalculateDuration<T>(DbCommandInterceptionContext<T> context)
    {
        return (DateTime.Now - (DateTime)context.FindUserState("start")).TotalMilliseconds;
    }
    private static bool HasFailed<T>(DbCommandInterceptionContext<T> context)
    {
        return context.OriginalException != null || (context.IsAsync && context.TaskStatus != TaskStatus.RanToCompletion);
    }
    private static string FormatParams(ICollection dbParameterCollection)
    {
        if (dbParameterCollection.Count == 0)
            return string.Empty;
        var parameterDescriptor = new StringBuilder();
        foreach (SqlParameter parameter in dbParameterCollection)
        {
            parameterDescriptor.AppendFormat("{0} {1}: {2}, ", parameter.DbType, parameter.ParameterName, parameter.Value);
        }
        return parameterDescriptor.ToString().TrimEnd(' ', ',');
    }
}

当然，Console.WriteLine可以用您自己的记录器替换。

如您所见，您可以使用 OriginalException 属性读取异常。这里听听其他感兴趣的属性。

注册实现的简短指南也可以在这里找到：

注册拦截器 创建实现一个或多个拦截接口的类后，可以使用 DbInterception 类向 EF 注册该类

还可以使用基于 DbConfiguration 代码的配置在应用域级别注册拦截器

您还可以使用 app.config 文件配置拦截器