How can I get the parameters of an Entity Framework query?

entity-framework, entity-framework-6

Solution

It's frustratingly complicated, in my experience, but this code got me there:

        var dbQuery = (DbQuery<T>)query;
        // get the IInternalQuery internal variable from the DbQuery object
        var iqProp = dbQuery.GetType().GetProperty("InternalQuery", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
        var iq = iqProp.GetValue(dbQuery, null);
        // get the ObjectQuery internal variable from the IInternalQuery object
        var oqProp = iq.GetType().GetProperty("ObjectQuery", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public);
        var objectQuery = (ObjectQuery<T>)oqProp.GetValue(iq, null);

        var sqlString = objectQuery.ToTraceString(); // this will populate the parameters collection
        foreach (var objectParam in objectQuery.Parameters)
        {
            Console.WriteLine($"{objectParam.Name} = {objectParam.Value.ToString()}");
        }

Note that this code only works for `IQueryable<T>` objects that are actually `DbQuery<T>`, as are created by entity framework. If you intend to wrap this in a utility method, some type checking may be in order.

Problem

Original source