How to get underlying type from typed DataSet

Question

I've been searching a lot but I haven't found anything about this question. I'm making a log of my app and I'm printing types of variables and their values. I want to do the same for every object I receive as parameter, and for every object I return too. So I'm returning a typed dataset (MyDataSet that's defined as MyDataSetType e.g.) but I can't retrieve MyDataSetType name.

I have a method that given a dataset, returns a string with all the content. Something like this:

    string GetLogStringFromDataSetParameter(System.Data.DataSet incomingDataSet)
    {
        StringBuilder strReturn = new StringBuilder();
        strReturn.Append("DataSet (type ");
        strReturn.Append(GetTypeName(incomingDataSet));
        strReturn.Append("). ");
        // .. do some validations
        strReturn.Append("Contains ");
        strReturn.Append(incomingDataSet.Tables.Count);
        strReturn.Append(" tables.");
        for (int i = 0; i < incomingDataSet.Tables.Count; i++)
        {
            System.Data.DataTable table = incomingDataSet.Tables[i];
            strReturn.Append(" Tabla " + table.TableName + " (" + i + ") ");
            strReturn.Append(<Method to list table content>);
        }//yes, this could have been a foreach loop...
        return FormatStringToLog(strReturn);
     }  //end

As you can see, I'm using my own method GetTypeName to retrieve de name of my typed dataset. I've made this method after some investigation through this site:

public static string GetTypeName<T>(T parameter)
{
    string strReturn = typeof(T).Name;
    if (strReturn.IndexOf("Nullable") >= 0)
        strReturn = Nullable.GetUnderlyingType(typeof(T)).Name;
    else if (strReturn.IndexOf("List") >= 0)
    {
        strReturn = "List of " + typeof(T).GetGenericArguments()[0].Name;
        if (strReturn.IndexOf("Nullable") >= 0)
            strReturn = "List of " +  Nullable.GetUnderlyingType(typeof(T).GetGenericArguments()[0]).Name;
    }
    return strReturn;
}

When I'm inside of GetLogStringFromDataSetParameter method, if I try typeof(MyDataSet) it returns correctly MyDataSetType. But when I make the call to GetTypeName it returns DataSet only, the generic type. Why is this? Is there any way to retrieve correctly MyDataSetType without calling directly to typeof()?

I hope I've explained everything clear enough. Thanks in advance.

Bul

Answer 1

That is because typeof(T) has nothing to do with the incoming Dataset type.

At compile-time the method is instantiated for the plain Datset type, and T is of type Dataset.

To solve it, simply use parameter.GetType() instead of typeof(T)

Wildeyed

I don't understand you completely. At compile-time the reference to IncomingDataSet should be solved with MyDataSet type, or there's something I'm missing... – Bul

Oh! I was using GetType() method since I couln't use typeof(T) – Bul

At compile-time your incomingDataset is of type System.Data.DataSet – Wildeyed