Override procedure..

ca guy

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"]);

9 Replies

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ca guy18y ago
ok. Thank you so much.
0
18y ago
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.
0
ca guy18y ago
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;
    }
}
0
Dave18y ago
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;
    }
}
0
18y ago
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
0
ca guy18y ago
Ok. Thank you for giving me start. You dont think writing override statements I can return multiple data types?
0
Dave18y ago
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.
0
ca guy18y ago
Hi..Thank you for your response. rs is the Recordset Object.
0
Dave18y ago
What type does the object rs have?
0