c# - 如何在我的程序中记录从 DbContext.SaveChanges() 生成的 SQL？

Question

根据这个线程，我们可以记录生成的SQLvia EF，但是呢DbContext.SaveChanges()？有没有任何简单的方法可以在没有任何额外框架的情况下完成这项工作？

Answer 1

在实体框架 6.0 中，Database 类有一个属性Action<string> Log。因此设置日志记录非常简单：

context.Database.Log = Console.WriteLine;

对于更高级的需求，您可以设置拦截器。

Answer 2

请参阅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

上下文的构造函数连接了 SavingChanges 事件（我只想为调试构建进行昂贵的反射）：

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。我从库克先生那里复制的代码将 DbParameter 转换为 SqlParamter，我将其保留原样，因为我正在访问 Sql Server，但我假设如果您访问其他类型的数据库，转换将失败。

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

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 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 4

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

创建你的拦截器

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，请确保您只执行一次，否则您最终会多次拦截相同的请求。

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 5

这做同样的事情，但是每次使用上下文时，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行版中编译。

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

这个 StackOverflow 解释了 Trace 和 Debug 之间的区别。

Answer 6

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

Answer 7

为 EF6 更新了 Tom Regan 的代码。

    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 8

这应该会有所帮助，EFTracingProvider

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