自定义 DbProviderServices 中的 CreateDbCommandDefinition 没有被调用？

Question

I need to intercept the call to the following method of DbProviderServices :

DbCommandDefinition CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree)

So I need to create a custom DbProviderServices , here it wraps the default SqlProviderServices and forwards the method calls inside (because SqlProviderServices is sealed). It looks something like this:

public class CustomDbProviderServices : DbProviderServices
{
    static readonly CustomDbProviderServices _instance = new CustomDbProviderServices();        
    static readonly SqlProviderServices _sqlProviderServices = SqlProviderServices.Instance;
    public static CustomDbProviderServices Instance => _instance;

    //other methods ...
}

I can confirm that the custom DbProviderServices is configured to replace the default one OK. Because I can see the code triggered in this overridden GetService method:

//_sqlProviderServices is the wrapped SqlProviderServices
public override object GetService(Type type, object key)
{
   //execution can hit in here
   return _sqlProviderServices.GetService(type, key);
}

But I've never seen a hit inside the following overridden method:

protected override DbCommandDefinition CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree)
{
    //forward call via the wrapped _sqlProviderServices
    ...
}

But somehow the queries run just fine without any error. So it's strange. I cannot imagine how and why it does not call that method as if it was unused. Could you think of any cause for this or it's just a normal behavior? If it's normal, where could I intercept it to get a reference to the DbCommandTree ?

Answer 1

Actually it's very weird to not call the overridden method of CreateDbCommandDefinition which looks likely that it should be called.

By debugging the source code of EF6, I can see that the actual DbProviderServices used by the code is EntityProviderServices , somehow at the time creating the command tree, that provider services is used instead of the custom one of mine.

Cannot explain this but looks like it's a change from EF5 -> EF6. The code in my question should work in EF5 but looks like it's broken when moved to EF6.

PS : I know that EF6 is the past and is going to be obsolete soon, but there are still legacy projects to work on and that's my case.