Queryable extension for sorting on strings

SortHelper.cs

void Main()
{    
    var collection = Student; // all students    
    collection.OrderBy("FirstName",true).Skip(0).Take(50).Select (s => new {s.StudentId, s.FirstName}).Dump();
    collection.OrderBy("FirstName",true).Skip(50).Take(50).Select (s => new {s.StudentId, s.FirstName}).Dump();
}

public static class SortHelper
{
    public static IQueryable<T> OrderBy<T>(this IQueryable<T> queryable, string propertyName, bool asc)
    {    
        var fieldToSort = typeof(T).GetFields().FirstOrDefault (x => x.Name == propertyName);
        if(fieldToSort != null)
        {
            return queryable.OrderBy (fieldToSort,asc);
        }
        var propertyToSort = typeof(T).GetProperties().FirstOrDefault (x => x.Name == propertyName);
        if(propertyToSort != null)
        {
            return queryable.OrderBy (propertyToSort,asc);
        }
        
        throw new ArgumentException("Invalid property / field name");
    }    
    
    public static IQueryable<T> OrderBy<T>(this IQueryable<T> queryable, PropertyInfo propertyInfo, bool asc)
    {
        var method = typeof(SortHelper).GetMethod("ApplyTypeSortProperty", BindingFlags.NonPublic | BindingFlags.Static);
        var generic = method.MakeGenericMethod(typeof(T),propertyInfo.PropertyType);
        return (IQueryable<T>)generic.Invoke(null, BindingFlags.NonPublic | BindingFlags.Static, null, new object[] { queryable, propertyInfo, asc }, null);        
    }    

    public static IQueryable<T> OrderBy<T>(this IQueryable<T> queryable, FieldInfo fieldInfo, bool asc)
    {
        var method = typeof(SortHelper).GetMethod("ApplyTypeSortField", BindingFlags.NonPublic | BindingFlags.Static);
        var generic = method.MakeGenericMethod(typeof(T),fieldInfo.FieldType);
        return (IQueryable<T>)generic.Invoke(null, BindingFlags.NonPublic | BindingFlags.Static, null, new object[] { queryable, fieldInfo, asc }, null);        
    }    
    
    private static IQueryable<T> ApplyTypeSortField<T,TProperty>(IQueryable<T> queryable, FieldInfo fieldInfo, bool asc)
    {
        var paramExpr = Expression.Parameter(typeof(T), "x");
        var propertyExpr = Expression.Field(paramExpr, fieldInfo);
        var propertyLambdaExpr = Expression.Lambda<Func<T, TProperty>>(propertyExpr, paramExpr);
        return asc ? queryable.OrderBy(propertyLambdaExpr) : queryable.OrderByDescending(propertyLambdaExpr); 
    }
    
    private static IQueryable<T> ApplyTypeSortProperty<T,TProperty>(IQueryable<T> queryable, PropertyInfo propertyInfo, bool asc)
    {
        var paramExpr = Expression.Parameter(typeof(T), "x");
        var propertyExpr = Expression.Property(paramExpr, propertyInfo);
        var propertyLambdaExpr = Expression.Lambda<Func<T, TProperty>>(propertyExpr, paramExpr);
        return asc ? queryable.OrderBy(propertyLambdaExpr) : queryable.OrderByDescending(propertyLambdaExpr); 
    }
}