Question

根据this帖子，我们可以通过SQL记录生成的EF，但DbContext.SaveChanges()呢？没有任何额外的框架，有没有简单的方法来完成这项工作？

Answer 1

在实体框架6.0中，Database类具有属性Action<string> Log。因此，设置日志记录非常简单：

context.Database.Log = Console.WriteLine;

如需更高级的需求，您可以设置interceptor。有关实体框架wiki

的更多信息

Answer 2

见http://www.codeproject.com/Articles/499902/Profiling-Entity-Framework-5-in-code。我使用Code First，POCO DbContext，Entity Framework 5在asp.net mvc应用程序中实现了Cook先生的想法。

应用程序的上下文类派生自DbContext：

public class MyDbContext : DbContext

上下文的构造函数挂钩了SavingChanges事件（我只想对调试版本进行昂贵的反射）：

public MyDbContext(): base("MyDbContext")
{
#if DEBUG
    ((IObjectContextAdapter)this).ObjectContext.SavingChanges += new EventHandler(objContext_SavingChanges);
#endif
}

保存更改事件将生成的sql写入输出窗口。我从库克先生复制的代码将DbParameter转换为SqlParamter，我保留原样，因为我正在使用Sql Server，但我假设如果您正在使用其他类型的数据库，转换将会失败。 / p>

public void objContext_SavingChanges(object sender, EventArgs e)
    {
        var commandText = new StringBuilder();

        var conn = sender.GetType()
             .GetProperties(BindingFlags.Public | BindingFlags.Instance)
             .Where(p => p.Name == "Connection")
             .Select(p => p.GetValue(sender, null))
             .SingleOrDefault();
        var entityConn = (EntityConnection)conn;

        var objStateManager = (ObjectStateManager)sender.GetType()
              .GetProperty("ObjectStateManager", BindingFlags.Instance | BindingFlags.Public)
              .GetValue(sender, null);

        var workspace = entityConn.GetMetadataWorkspace();

        var translatorT =
            sender.GetType().Assembly.GetType("System.Data.Mapping.Update.Internal.UpdateTranslator");

        var translator = Activator.CreateInstance(translatorT, BindingFlags.Instance |
            BindingFlags.NonPublic, null, new object[] {objStateManager,workspace,
            entityConn,entityConn.ConnectionTimeout }, CultureInfo.InvariantCulture);

        var produceCommands = translator.GetType().GetMethod(
            "ProduceCommands", BindingFlags.NonPublic | BindingFlags.Instance);

        var commands = (IEnumerable<object>)produceCommands.Invoke(translator, null);

        foreach (var cmd in commands)
        {
            var identifierValues = new Dictionary<int, object>();
            var dcmd =
                (DbCommand)cmd.GetType()
                   .GetMethod("CreateCommand", BindingFlags.Instance | BindingFlags.NonPublic)
                   .Invoke(cmd, new[] { translator, identifierValues });

            foreach (DbParameter param in dcmd.Parameters)
            {
                var sqlParam = (SqlParameter)param;

                commandText.AppendLine(String.Format("declare {0} {1} {2}",
                                                        sqlParam.ParameterName,
                                                        sqlParam.SqlDbType.ToString().ToLower(),
                                                        sqlParam.Size > 0 ? "(" + sqlParam.Size + ")" : ""));

                commandText.AppendLine(String.Format("set {0} = '{1}'", sqlParam.ParameterName, sqlParam.SqlValue));
            }

            commandText.AppendLine();
            commandText.AppendLine(dcmd.CommandText);
            commandText.AppendLine("go");
            commandText.AppendLine();
        }

        System.Diagnostics.Debug.Write(commandText.ToString());
    }

Answer 3

如果要使用拦截器捕获使用EF6生成的实际SQL（可能稍后播放），您可以执行以下操作。

创建拦截器

public class InsertUpdateInterceptor : IDbCommandInterceptor
{
    public virtual void NonQueryExecuting(
        DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
        logCommand(command);
    }

    public virtual void ReaderExecuting(
        DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
        // this will capture all SELECT queries if you care about them..
        // however it also captures INSERT statements as well 
        logCommand(command);
    }

    public virtual void ScalarExecuting(
     DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
        logCommand(command);
    }


    private void logCommand(DbCommand dbCommand)
    {
        StringBuilder commandText = new StringBuilder();

        commandText.AppendLine("-- New statement generated: " + System.DateTime.Now.ToString());
        commandText.AppendLine();

        // as the command has a bunch of parameters, we need to declare
        // those parameters here so the SQL will execute properly

        foreach (DbParameter param in dbCommand.Parameters)
        {
            var sqlParam = (SqlParameter)param;

            commandText.AppendLine(String.Format("DECLARE {0} {1} {2}",
                                                    sqlParam.ParameterName,
                                                    sqlParam.SqlDbType.ToString().ToLower(),
                                                    getSqlDataTypeSize(sqlParam));

            var escapedValue = sqlParam.SqlValue.replace("'", "''");
            commandText.AppendLine(String.Format("SET {0} = '{1}'", sqlParam.ParameterName, escapedValue ));
            commandText.AppendLine();
        }

        commandText.AppendLine(dbCommand.CommandText);
        commandText.AppendLine("GO");
        commandText.AppendLine();
        commandText.AppendLine();

        System.IO.File.AppendAllText("outputfile.sql", commandText.ToString());
    }

    private string getSqlDataTypeSize(SqlParameter param)
    {
        if (param.Size == 0)
        {
            return "";
        }

        if (param.Size == -1)
        {
            return "(MAX)";
        }

        return "(" + param.Size + ")";
    }


    // To implement the IDbCommandInterceptor interface you need to also implement these methods like so

    public void NonQueryExecuted(
        DbCommand command, DbCommandInterceptionContext<int> interceptionContext)
    {
    }

    public void ReaderExecuted(
        DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext)
    {
    }

    public void ScalarExecuted(
        DbCommand command, DbCommandInterceptionContext<object> interceptionContext)
    {
    }
}

你还需要注册你的拦截器。如果您在ASP.NET应用程序中执行此操作，请确保只执行一次，否则您最终会多次拦截同一请求。

示例DAO

public class MyDataDAO
{
    private static bool isDbInterceptionInitialised = false;

    public MyDataDAO()
    {
        if (!isDbInterceptionInitialised)
        {
            DbInterception.Add(new InsertUpdateInterceptor());
            isDbInterceptionInitialised = true;
        }
    }

    public void Insert(string dataToInsert)
    {
        using (myentities context = new myentities())
        {
            MyData myData = new MyData();
            myData.data = dataToInsert;

            // this will trigger the interceptor
            context.SaveChanges();
        }
    }
}

Answer 4

对于短期日志记录，我只是放入DbContext构造函数：

Database.Log = x => Debug.WriteLine(x);

添加/删除SQL的日志记录非常快。对于长期使用期限，可以用支票包裹

#IFDEF DEBUG // or something similar

Answer 5

这也是一样的，但每次使用上下文时，它都会在输出窗口中编写sql查询。不同之处在于它不会在发布中编译。

public MyEntitities()
    : base()
{
    Database.Log = s => System.Diagnostics.Trace.WriteLine(s);
}

This StackOverflow Explains the Difference between Trace and Debug.

Answer 6

Tom Regan为EF6更新了代码。

    public void objContext_SavingChanges(object sender, EventArgs e)
    {
        var commandText = new StringBuilder();

        var conn = sender.GetType()
             .GetProperties(BindingFlags.Public | BindingFlags.Instance)
             .Where(p => p.Name == "Connection")
             .Select(p => p.GetValue(sender, null))
             .SingleOrDefault();
        var entityConn = (EntityConnection)conn;

        var objStateManager = (System.Data.Entity.Core.Objects.ObjectStateManager)sender.GetType()
              .GetProperty("ObjectStateManager", BindingFlags.Instance | BindingFlags.Public)
              .GetValue(sender, null);

        var workspace = entityConn.GetMetadataWorkspace();

        var translatorT =
            sender.GetType().Assembly.GetType("System.Data.Entity.Core.Mapping.Update.Internal.UpdateTranslator");

        var entityAdapterT =
            sender.GetType().Assembly.GetType("System.Data.Entity.Core.EntityClient.Internal.EntityAdapter");
        var entityAdapter = Activator.CreateInstance(entityAdapterT, BindingFlags.Instance |
            BindingFlags.NonPublic | BindingFlags.Public, null, new object[] { sender }, System.Globalization.CultureInfo.InvariantCulture);

        entityAdapterT.GetProperty("Connection").SetValue(entityAdapter, entityConn);

        var translator = Activator.CreateInstance(translatorT, BindingFlags.Instance |
            BindingFlags.NonPublic | BindingFlags.Public, null, new object[] { entityAdapter }, System.Globalization.CultureInfo.InvariantCulture);

        var produceCommands = translator.GetType().GetMethod(
            "ProduceCommands", BindingFlags.NonPublic | BindingFlags.Instance);

        var commands = (IEnumerable<object>)produceCommands.Invoke(translator, null);

        foreach (var cmd in commands)
        {
            var identifierValues = new Dictionary<int, object>();
            var dcmd =
                (System.Data.Common.DbCommand)cmd.GetType()
                   .GetMethod("CreateCommand", BindingFlags.Instance | BindingFlags.NonPublic)
                   .Invoke(cmd, new[] { identifierValues });

            foreach (System.Data.Common.DbParameter param in dcmd.Parameters)
            {
                var sqlParam = (SqlParameter)param;

                commandText.AppendLine(String.Format("declare {0} {1} {2}",
                                                        sqlParam.ParameterName,
                                                        sqlParam.SqlDbType.ToString().ToLower(),
                                                        sqlParam.Size > 0 ? "(" + sqlParam.Size + ")" : ""));

                commandText.AppendLine(String.Format("set {0} = '{1}'", sqlParam.ParameterName, sqlParam.SqlValue));
            }

            commandText.AppendLine();
            commandText.AppendLine(dcmd.CommandText);
            commandText.AppendLine("go");
            commandText.AppendLine();
        }

        System.Diagnostics.Debug.Write(commandText.ToString());
    }

Answer 7

您可以使用SQL Server Profiler并针对要连接的数据库服务器运行它。

Answer 8

这应该有帮助，EFTracingProvider

http://code.msdn.microsoft.com/EFProviderWrappers

如何在我的程序中从DbContext.SaveChanges（）记录生成的SQL？

8 个答案: