实体框架4.1 - EFTracingProvider

问题描述：

有没有一种方法，使 EFTracing提供商工作，EF 4.1？

Is there a way to make the EFTracing provider work with EF 4.1?

EFTracing似乎需要一个ObjectContext的，我用的DbContext。

EFTracing seems to need an objectcontext and I use dbcontext.

在此先感谢！

答

是的，可以。我使用的是与两个数据库第一DbContexts和code-第一DbContexts的社区版。这个答案是基于讨论帖项目工地上。

Yes, you can. I'm using the community version with both database-first DbContexts and code-first DbContexts. This answer is based on a discussion thread on the project site.

有关数据库第一/设计师DbContexts（通过ADO.NET的DbContext生成模板），你可以简单地添加下面的构造：

For database-first/designer DbContexts (via ADO.NET DbContext Generator templates), you can simply add the following constructor:

public abstract class MyDbContext : DbContext
{
    protected MyDbContext(string nameOrConnectionString)
        : base(EFTracingProviderUtils.CreateTracedEntityConnection(nameOrConnectionString), true)
    {
        // enable sql tracing
        ((IObjectContextAdapter) this).ObjectContext.EnableTracing();
    }
}

有关code首先DbContexts其更复杂一些，因为EFTracingProvider想要一个完整的实体连接字符串。您必须手动创建EFTracingConnection的一个实例。下面的例子将两个数据库第一和code第一环境工作。

For code first DbContexts its a bit more complicated since the EFTracingProvider wants a full entity connection string. You have to create an instance of EFTracingConnection manually. The following example will work for both database first and code first contexts.

public abstract class MyDbContext : DbContext
{
    protected MyDbContext(string nameOrConnectionString)
        : base(CreateTracingConnection(nameOrConnectionString), true)
    {
        // enable sql tracing
        ((IObjectContextAdapter) this).ObjectContext.EnableTracing();
    }

    private static DbConnection CreateTracingConnection(string nameOrConnectionString)
    {
        try
        {
            // this only supports entity connection strings http://msdn.microsoft.com/en-us/library/cc716756.aspx
            return EFTracingProviderUtils.CreateTracedEntityConnection(nameOrConnectionString);
        }
        catch (ArgumentException)
        {
            // an invalid entity connection string is assumed to be a normal connection string name or connection string (Code First)

            ConnectionStringSettings connectionStringSetting =
                ConfigurationManager.ConnectionStrings[nameOrConnectionString];
            string connectionString;
            string providerName;

            if (connectionStringSetting != null)
            {
                connectionString = connectionStringSetting.ConnectionString;
                providerName = connectionStringSetting.ProviderName;
            }
            else
            {
                providerName = "System.Data.SqlClient";
                connectionString = nameOrConnectionString;
            }

            return CreateTracingConnection(connectionString, providerName);
        }
    }

    private static EFTracingConnection CreateTracingConnection(string connectionString, string providerInvariantName)
    {
        // based on the example at http://jkowalski.com/2010/04/23/logging-sql-statements-in-entity-frameworkcode-first/
        string wrapperConnectionString =
            String.Format(@"wrappedProvider={0};{1}", providerInvariantName, connectionString);

        EFTracingConnection connection =
            new EFTracingConnection
                {
                    ConnectionString = wrapperConnectionString
                };

        return connection;
    }
}

实体框架4.1 - EFTracingProvider

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