Data Serialization ?

[WJ]

Hello,

I got an exception telling me that Invalid Casting on a Date field. Here is
what I attempted to do in my Asp.Net app:

1. A class that contains 4 fields called Employee Record (eye), two out of 4
fields are DateTime type. The class name is "eyeClass".

******** Code sample *********

using System;

namespace hr.eye
{
[Serializable]
public class eyeClass
{
private string _LastName;
private string _FirstName;
private DateTime _BirthDate;
private DateTime _HireDate;

public eyeClass()
{
}

public eyeClass
(
string LastName
,string FirstName
,DateTime BirthDate
,DateTime HireDate
)

{
this._LastName=LastName;
this._FirstName=FirstName;
this._BirthDate=BirthDate;
this._HireDate=HireDate;
}

public string LastName {get{return _LastName;}}
public string FirstName {get{return _FirstName;}}
public DateTime BirthDate {get{return _BirthDate;}}
public DateTime HireDate {get{return _HireDate;}}
}
}
On Asp.Net Page Behind code (onReadDataOKClick button): I have the following
codes:

DataSet ds=new DataSet();
Call SqlHelper.FillDataset to extract data into ds; //it returned two
tables with data (one record per table).

//this instruction below attempts to fill "eyeClass" with data retrieved
from DataSet .
//Exception is thrown when any DateField is NULL. (Invalid Casting)

eyeClass eye=new eyeClass(
ds.Tables[0].Rows[0]["LastName"].ToString()
,ds.Tables[0].Rows[0]["FirstName"].ToString()
,(DateTime)ds.Tables[0].Rows[0]["BirthDate"]
,(DateTime)ds.Tables[0].Rows[0]["HireDate"]);

******** Code sample Ended *********

Problem: The exception is thrown on the HireDate because it is NULL and I
need it to be nulled in some cases. I cannot trap the message here with the
TRY/Catch.

My question is: How can I force the application just go ahead to eat the
"exception"... and move on instead of exiting the program completely.

Thanks

John

 

[Guest]

Why not take the information out first and then create the object. Something
like:

if(ds.Tables[0].Rows[0]["DateField"]==DbNull.Value)
tempDateHolder=ds.Tables[0].Rows[0]["DateField"];
else
tempDateHolder=new DateTime(1,0,0,0,0,0);

Then, in the class you can test for the "null" date.

If you use strongly typed DataSets, you can test for a NULL more elegantly.

Unfortunately, you cannot blow through an error on a constructor.

---

Gregory A. Beamer
MVP; MCP: +I, SE, SD, DBA

***************************
Think Outside the Box!
***************************

Hello,

I got an exception telling me that Invalid Casting on a Date field. Here is
what I attempted to do in my Asp.Net app:

1. A class that contains 4 fields called Employee Record (eye), two out of 4
fields are DateTime type. The class name is "eyeClass".

******** Code sample *********

using System;

namespace hr.eye
{
[Serializable]
public class eyeClass
{
private string _LastName;
private string _FirstName;
private DateTime _BirthDate;
private DateTime _HireDate;

public eyeClass()
{
}

public eyeClass
(
string LastName
,string FirstName
,DateTime BirthDate
,DateTime HireDate
)

{
this._LastName=LastName;
this._FirstName=FirstName;
this._BirthDate=BirthDate;
this._HireDate=HireDate;
}

public string LastName {get{return _LastName;}}
public string FirstName {get{return _FirstName;}}
public DateTime BirthDate {get{return _BirthDate;}}
public DateTime HireDate {get{return _HireDate;}}
}
}
On Asp.Net Page Behind code (onReadDataOKClick button): I have the following
codes:

DataSet ds=new DataSet();
Call SqlHelper.FillDataset to extract data into ds; //it returned two
tables with data (one record per table).

//this instruction below attempts to fill "eyeClass" with data retrieved
from DataSet .
//Exception is thrown when any DateField is NULL. (Invalid Casting)

eyeClass eye=new eyeClass(
ds.Tables[0].Rows[0]["LastName"].ToString()
,ds.Tables[0].Rows[0]["FirstName"].ToString()
,(DateTime)ds.Tables[0].Rows[0]["BirthDate"]
,(DateTime)ds.Tables[0].Rows[0]["HireDate"]);

******** Code sample Ended *********

Problem: The exception is thrown on the HireDate because it is NULL and I
need it to be nulled in some cases. I cannot trap the message here with the
TRY/Catch.

My question is: How can I force the application just go ahead to eat the
"exception"... and move on instead of exiting the program completely.

Thanks

John

 

[WJ]

Why not take the information out first and then create the object.
Something
like:

if(ds.Tables[0].Rows[0]["DateField"]==DbNull.Value)
tempDateHolder=ds.Tables[0].Rows[0]["DateField"];
else
tempDateHolder=new DateTime(1,0,0,0,0,0);

Thanks Cowboy. But this is too obvious. And filling the date field with a
bogus date is prohibited in my project. It is either valid or dbNull.Value.
Nothing else.

John