Override procedure..

Question

Hi..
    I am new to c#. I want to write common procedure , when I pass database field as a parameter to procedure, if field has value just return the value or if field type is numeric then reurn 0 or if it is string then return ""..depending upon datatype of field being passed.
   Something like this considering CheckNull is the name of procedure..
     txtCode.Text=CheckNull(rs.Fields["ID"]);
     txtDate.Text=CheckNull(rs.Fields["SaleDate"]);
     txtYear.Text=CheckNull(rs.Fields["NoofYears"]);

ca guy · Answer

ok. Thank you so much.

Brandon Lewis · Answer

private object CheckValue( object theDBObject) { switch (theDBObject.GetType().ToString()) { case System.Int32: return 0; case System.String: return String . Empty ; ... default : break ; } } Then just cast the object back to what you need it to be using a TryParse method.

ca guy · Answer

Yes ..sorry I meant Overloading. I have been using delphi..new to c#. In example you gave here you are returning only datatype as string. Is this possible? What return data type I need to give here? private string CheckValue(Object theDBObject) { switch (theDBObject.GetType().ToString()) { case System.int32: return 0; case System.String: return ; ... default: break; } }

Dave · Answer

When you say override  do you mean overloaded ? You could write overloaded methods. Another idea would be to use a switch statement. Something like: private string CheckValue(Object theDBObject) { switch (theDBObject.GetType().ToString()) { case System.int32: return int; case System.String: return String; ... default: break; } }

Brandon Lewis · Answer

In order to override a method the method first needs to be inherited from a parent class and the method needs to be a virtual method. Is there some else your meaning to do? Strings are reference type variables while integers are value types. You could try doing something like: if (myVar.GetType().IsValueType) //Do something else //Do something else

ca guy · Answer

Ok. Thank you for giving me start. You dont think writing override statements I can return multiple data types?

Dave · Answer

ADO.NET (and therefore C#) does not have a RecordSet class. I'll give you some ideas based on the assumption that you are using a DataReader (you may want to Google a tutorial on how to use the DataReader class). I cannot think of a way off the top of my head for a method that will be able to check for both value types and reference types. But here is a suggestion for checking for nulls: private bool CheckNull(Object anObject) { if(anObject == null) return true; else return false; } You could call this with something like: bool isItNull = CheckNull(instanceDataReader.GetValue()); If the line if(anObject == null) does not work you could try if(anObject is DBNull) I have not tested my suggestions so no guarantees that they'll work.

ca guy · Answer

Hi..Thank you for your response. rs is the Recordset Object.

Dave · Answer

What type does the object rs have?