Dynamic for unknown type, how else could be this implemented?

Question

I have some classes (entities) that represent database tables

public class ALBUM
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Tracks { get; set; }
}
public class BOOK
{
    public int Id { get; set; }
    public string Author { get, set; }
}

Then to get parameters to respective stored procedures, insert, update, any

public Command getParameters(string spName, dynamic entity, Connection conn)
{
   Command cmd = conn.CreateCommand();
   cmd.CommandType = CommandType.StoredProcedure;
   cmd.CommandText = spName;

   // Get properties (fields) from entity (table)
   PropertyInfo[] properties = entity.GetType().GetProperties();

   for (int = 0; i < properties.Length; i++)
   {
       // here I set Parameters: name, DBType, and Value from properties
   }
}

Now I call

public void Some()
{
   ALBUM someAlbum = new ALBUM();
   BOOK anyBook = new BOOK();      // all respective data from DB is set

   Command newCommand = getParameters("myAlbumSP", someAlbum, myConnection);
   Command newCommand = getParameters("mySPBooks", anyBook, myConnection);
}

How else colud I define "entity" parameter?, not to be dynamic.
It works, just I'm lookin for some other way to do it, I´m sure there is plenty of.

score 2 · Accepted Answer · answered Mar 16 '13 at 00:27

2

In your case, entity does not need to be dynamic (although it is certainly OK). Using object instead would be sufficient, because you do not call anything outside of what object gives you. This works, because you use reflection. With dynamic, on the other hand, you could specify properties not found on object, and the compiler would not complain.

For example, since both ALBUM and BOOK have an Id parameter, you could write something like this:

var entityId = entity.Id;

This would work as long as entity is dynamic; it would not work with an object.

answered Mar 16 '13 at 00:27

Sergey Kalinichenko

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I see, and is there any difference between them (object - dynamic) talking about memory resources, or speed? – Shin Mar 16 '13 at 00:43
2

+1. @Eduardo, comparing `object` and `dynamic` on speed is very hard in general because you can't do `objectMy.Id` unlike `dynamicMy.Id`. In your particular case since your code uses zero functionality from `dynamic` there is unlikely to be measurable difference (try yourself - potentially dynamic would be a bit slower). Also require caller to pass more complex type (`dynamic` vs. `object`) for no good reason is not sign of good code. – Alexei Levenkov Mar 16 '13 at 04:56

score 0 · Answer 2 · edited May 23 '17 at 10:25

You could use the ExpandoObject class. As Paul Sasik said:

Expando is a dynamic type designed to handle dynamic data by adding/removing members at runtime. dynamic is designed to allow .NET to interoperate with types when interfacing with dynamic typing languages such as Python and JavaScript.

https://stackoverflow.com/a/3540291/322848

Here is an article that explains the ExpandoObject:

http://blogs.msdn.com/b/csharpfaq/archive/2009/10/01/dynamic-in-c-4-0-introducing-the-expandoobject.aspx

Dynamic for unknown type, how else could be this implemented?

2 Answers2