Is there any way to trace\log the sql using Dapper?



Is there a way to dump the generated sql to the Debug log or something? I'm using it in a winforms solution so the mini-profiler idea won't work for me.

Accepted Answer

I got the same issue and implemented some code after doing some search but having no ready-to-use stuff. There is a package on nuget MiniProfiler.Integrations I would like to share.

Update V2: it supports to work with other database servers, for MySQL it requires to have MiniProfiler.Integrations.MySql

Below are steps to work with SQL Server:

1.Instantiate the connection

var factory = new SqlServerDbConnectionFactory(_connectionString);
using (var connection = DbConnectionFactoryHelper.New(factory, CustomDbProfiler.Current))
 // your code

2.After all works done, write all commands to a file if you want

File.WriteAllText("SqlScripts.txt", CustomDbProfiler.Current.ProfilerContext.BuildCommands());

Expert Answer

Dapper does not currently have an instrumentation point here. This is perhaps due, as you note, to the fact that we (as the authors) use mini-profiler to handle this. However, if it helps, the core parts of mini-profiler are actually designed to be architecture neutral, and I know of other people using it with winforms, wpf, wcf, etc - which would give you access to the profiling / tracing connection wrapper.

In theory, it would be perfectly possible to add some blanket capture-point, but I'm concerned about two things:

  • (primarily) security: since dapper doesn't have a concept of a context, it would be really really easy for malign code to attach quietly to sniff all sql traffic that goes via dapper; I really don't like the sound of that (this isn't an issue with the "decorator" approach, as the caller owns the connection, hence the logging context)
  • (secondary) performance: but... in truth, it is hard to say that a simple delegate-check (which would presumably be null in most cases) would have much impact

Of course, the other thing you could do is: steal the connection wrapper code from mini-profiler, and replace the profiler-context stuff with just: Debug.WriteLine etc.

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Is this KB legal? Yes, learn why