Data store command interception

[Bartmax]

Is there any extensible point on where EF hits the db, something that can be overridable to log or do anything everytime a hit to the db.

im wondering of something like

override OnDatabaseHit(Operation op, Context context) {
     if (typeof(op) == Query | SaveChanges | ... {
         Console.WriteLine(context.Query)
     }
}

if not, take it as a suggestion for EF7 :)

[rowanmiller]

This is more generally covered by #626 but we'll leave this one active to track the particular scenario of intercepting database commands. Something like IDbCommandInterceptor from EF6.x.

[NikolajDL]

Is there a time frame for something like IDbCommandInterceptor to be added to EF7? Using EF6 with ASP.NET 5 is a pain compared to EF7, but I really need the IDbCommandInterceptor to implement seamless row level security in EF7.

[rowanmiller]

@excolo it will be post 1.0.0 release. You may be able to achieve something similar now if you start mucking around with replacing/wrapping low level services... but this item is about building a more usable experience.

[MariovanZeist]

@rowanmiller Can you give a hint on which low level service to wrap? I tried overriding the Open function in SqlServerConnection but it seems like this class is used for accessing metadata and not data related to a DbContext

    public class TestSqlServerConnection : SqlServerConnection
    {
        public TestSqlServerConnection(IDbContextOptions options, ILogger<SqlServerConnection> logger) 
            : base(options, logger)
        {
        }

        public override void Open()
        {
            base.Open();
            //Set session context
            var cmd = DbConnection.CreateCommand();
            cmd.CommandText = "EXEC sp_set_session_context @key=N'CompanyId', @value=1";
            cmd.ExecuteNonQuery();
        }
    }

[MariovanZeist]

It might have to do with how I register the above class (I might have to do some more detective work to get it to work)
I register the above class in my ConfigureServices function (before the call to AddEntityFramework) with

services.TryAddScoped<ISqlServerConnection,TestSqlServerConnection>();

But when I run the following code from dbContext it will still return an instance of SqlServerConnection instead of TestSqlServerConnection

    public class TestDbContext : DbContext
    {
        public ISqlServerConnection TestConnection()
        {
            return this.GetService<ISqlServerConnection>();
        }
    }

[rowanmiller]

@MariovanZeist use AddScoped instead of TryAddScoped

[MariovanZeist]

@rowanmiller
My issue was actually RTFM related. Instead of creating the DbContext using DI, I was creating it by hand (using Activator.CreateInstance()) which I obviously shouldn't do. That's why it didn't pick up my ISqlServerConnection implementation.

I think i fell into the trap referenced by #4668

[rowanmiller]

@MariovanZeist 👍 - the changes from #4668 are being worked on at the moment

[wpostma]

I put a question on stack-overflow to seek alternative techniques for EF Core.

http://stackoverflow.com/questions/37660746/can-i-configure-an-interceptor-yet-in-entityframework-core

Instead of a heavyweight framework approach perhaps whatever replaces interceptors could be a very lightweight and simple pattern.