Die Art oder Methode hat drei allgemeine Parameter (s), aber zwei generisches Argument (e)

Question

zur Verfügung gestellt wurde habe ich den folgenden Arbeits Code:

Context context = new Context(_options); 

Expression<Func<Context.Person, Context.Address>> e1 = x => x.Address; 
Expression<Func<Context.Address, Context.Country>> e2 = x => x.Country; 

IIncludableQueryable<Context.Person, Context.Address> a = context.Persons.Include(e1); 
IIncludableQueryable<Context.Person, Context.Country> b = a.ThenInclude(e2); 

List<Context.Person> result = context.Persons.Include(e1).ThenInclude(e2).ToList(); 

Wo Include und ThenInclude sind Methoden Erweiterung Entity Framework-Core.

In meinem Code muss ich generische Typen verwenden, so dass ich Reflexion bin mit:

IQueryable<Context.Person> persons = context.Persons; 

MethodInfo include = typeof(EntityFrameworkQueryableExtensions).GetMethods().First(x => x.Name == "Include" && x.GetParameters().Select(y => y.ParameterType.GetGenericTypeDefinition()).SequenceEqual(new[] { typeof(IQueryable<>), typeof(Expression<>) })); 

MethodInfo thenInclude = typeof(EntityFrameworkQueryableExtensions).GetMethods().First(x => x.Name == "ThenInclude" && x.GetParameters().Select(y => y.ParameterType.GetGenericTypeDefinition()).SequenceEqual(new[] { typeof(IIncludableQueryable<,>), typeof(Expression<>) })); 

Expression<Func<Context.Person, Context.Address>> l1 = x => x.Address; 

Expression<Func<Context.Address, Context.Country>> l2 = x => x.Country; 


try { 

    MethodInfo includeInfo = include.MakeGenericMethod(typeof(Context.Person), l1.ReturnType); 

    IIncludableQueryable<Context.Person, Context.Address> r1 = (IIncludableQueryable<Context.Person, Context.Address>)includeInfo.Invoke(null, new Object[] { persons, l1 }); 

    MethodInfo thenIncludeInfo = thenInclude.MakeGenericMethod(typeof(Context.Address), l2.ReturnType); 

    IIncludableQueryable<Context.Address, Context.Country> r2 = (IIncludableQueryable<Context.Address, Context.Country>)thenIncludeInfo.Invoke(null, new Object[] { r1, l2 }); 

    var r = r2.AsQueryable(); 

} catch (Exception ex) { } 

Aber auf dieser Code-Zeile:

MethodInfo thenIncludeInfo = thenInclude.MakeGenericMethod(typeof(Context.Address), l2.ReturnType); 

bekomme ich folgende Fehlermeldung:

The type or method has 3 generic parameter(s), but 2 generic argument(s) were provided. A generic argument must be provided for each generic parameter. 

Ich kann den Fehler verstehen, indem ich auf ThenInclude Definition schaue, aber ich bin mir nicht sicher, wie man es löst ...

Answer 1

Wie die Nachricht andeutet, erwartet ThenInclude 3 Typparameter: TEntity, TPreviousProperty, TProperty. Aus dem Code, so scheint es, dies funktionieren würde:

MethodInfo thenIncludeInfo = thenInclude.MakeGenericMethod(
    typeof(Context.Person), typeof(Context.Address), l2.ReturnType);