How to get the value of a ParameterExpression?

Question

.NET

I need to upgrade Ef Core (5). There is some function in the request, which should not be translated into a database function, but turned into a different construct (Expression).
To do this, I intercepted the traversal of the entire expression through the substitution of EF services.
The problem is that the function takes some object as a parameter and in my visitor I get a MethodCallExpression with a ParameterExpression that contains the parameter name and type. And to build the correct expression, I need the value of this parameter.

Here is an example request code

var myObject = new SomeObject();

ctx.MyEntity
    .Where(x => x.MyFunction(myObject))
    .ToList();

and this very myObject is what I need in my visitor. If I connected the visitor directly in the request function, I could pass an additional parameter to it with the value of the object. But then you would have to attach a visitor to each request, and this is inconvenient, ugly and generally atta.

Therefore, in the registration of EF services, I replaced QueryTranslationPreprocessor with my own.

The constructor for this service takes QueryTranslationPreprocessorDependencies and QueryCompilationContext as parameters.
I tried to find some way to get my object through these objects, but I did not find it. Either I searched badly, or through them it is impossible.
Also, the first expression in the overridden QueryTranslationPreprocessor.Process(Expression) method is QueryRootExpression. I also tried to find some links to my object in it.

Also, I was able to prohibit broadcasting objects of the SomeObject type through IEvaluatableExpressionFilterPlugin. After that, this object began to come to my visitor as a MemberExpression. This is closer (possibly) as it is no longer just a parameter, but an expression containing the MemberInfo. And this object is a class field (formed from the function inside which the request is created). That is, to get Member.GetValue(), I need to pass an instance of an object of type Member.DeclaringType there. But I don't know where to get it either.

Probably, I explained the essence of the problem too complicated and abstractly. So I will answer the leading questions.

Answer 1

It is not clear why such difficulties? Why not build Expression in advance and throw it into filters as needed?