Re: DBNull.Value to string - C# Discussion Boards

19-Oct-05 23:43

Hi,

I have the following function that checks a database field for DBNull.Value. If it contains DBNull.Value, the it should return "", otherwise the string.

This is my calling function (objCustomer is an instance of the Customer class):

objCustomer.AddressLine1 = Globals.CheckStringForDBNulls(objDr["Address1"]);

This is my static function:

public static string CheckStringForDBNulls(string strCheckString)
{
if(strCheckString.Trim() == DBNull.Value)
return "";
else
return strCheckString.Trim();
}

Something tells me that my parameter string strCheckString is of the wrong type.

Please can someone help me correct this error/problem that I am having.

Regards.

-- modified at 5:45 Thursday 20th October, 2005

ZainAMJ20-Oct-05 0:11

20-Oct-05 0:11

ma se wrote:
objCustomer.AddressLine1 = Globals.CheckStringForDBNulls(objDr["Address1"]);

Try This

ma se wrote:
objCustomer.AddressLine1 = Globals.CheckStringForDBNulls(objDr["Address1"].ToString());

======================

ma se wrote:
if(strCheckString.Trim() == DBNull.Value)
return "";
else
return strCheckString.Trim();

TRY THIS

ma se wrote:
if(Convert.IsDBNull(strCheckString.Trim()))
return "";
else
return strCheckString.Trim();

AMJ (With "Z" Factor)

Brendan Vogt20-Oct-05 0:40

20-Oct-05 0:40

Cool and thanks.

ZainAMJ20-Oct-05 0:48

20-Oct-05 0:48

if(strCheckString.Trim() == DBNull.Value)
return "";
else
return strCheckString.Trim();

======

This can be reduced to ONE LINE IF STATEMENT Wink | ;)

explore your self and reduce your LOC Cost

AMJ (With "Z" Factor)

Brendan Vogt20-Oct-05 1:06

20-Oct-05 1:06

If I were to convert a null value coming from a database to something else, would this be good enough? I do not know to what date I should convert if it contains no values, so I chose 1900/01/01. Any ideas?

public static DateTime CheckDateForDBNulls(DateTime dtCheckDate)
{
if(Convert.IsDBNull(dtCheckDate))
return Convert.ToDateTime("1900/01/01");
else
return Convert.ToDateTime(dtCheckDate);
}

Calling function is:

objCustomer.StartDate = Globals.CheckDateForDBNulls(Convert.ToDateTime(objDr["StartDate"])); // Check for DBNull value

I get a horrible error:

Object cannot be cast from DBNull to other types.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidCastException: Object cannot be cast from DBNull to other types.

Please can you help again. Cool | :cool:

-- modified at 7:06 Thursday 20th October, 2005

ZainAMJ20-Oct-05 17:07

Re: DBNull.Value to string (Error In That Code)

20-Oct-05 17:07

objCustomer.StartDate = Globals.CheckDateForDBNulls(Convert.ToDateTime(objDr["StartDate"]));

Instead of implementing this, try this one

objCustomer.StartDate = Globals.CheckDateForDBNulls(objDr["StartDate"].ToString());

==========

In your static function try this

public static DateTime CheckDateForDBNulls(String dtCheckDate)
{
if(Convert.IsDBNull(dtCheckDate) && IsDate(dtCheckDate)==true)
return System.Date.MinValue;
else
return Convert.ToDateTime(dtCheckDate);
}

AMJ (With "Z" Factor)

ZainAMJ20-Oct-05 17:10

20-Oct-05 17:10

objCustomer.StartDate = Globals.CheckDateForDBNulls(Convert.ToDateTime(objDr["StartDate"]));

Instead of implementing this, try this one

objCustomer.StartDate = Globals.CheckDateForDBNulls(objDr["StartDate"].ToString());

==========

In your static function try this

public static DateTime CheckDateForDBNulls(String dtCheckDate)
{
if(Convert.IsDBNull(dtCheckDate) || IsDate(dtCheckDate)==false)
return System.Date.MinValue;
else
return Convert.ToDateTime(dtCheckDate);
}

AMJ (With "Z" Factor)

String conversion to DBNull.Value

Guffa20-Oct-05 1:31

Guffa

20-Oct-05 1:31

As the value can be different types of objects, use the object base class, and check the type of the object:

public static string CheckStringForDBNulls(object strCheckString) {<br />
	if (strCheckString is DBNull) {<br />
		return string.Empty;<br />
	} else {<br />
		return ((string)strCheckString).Trim();<br />
	}<br />
}

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Brendan Vogt19-Oct-05 23:35

19-Oct-05 23:35

Hi,

I tried the following function, but it doesn't want to work:

//*********************************************************************
//
// CheckStringForDBNulls Static Method
//
// The CheckStringForDBNulls method checks if a string contains a value, if not it
// returns DBNull.Value, or the value of the string.
//
//*********************************************************************

public static DBNull CheckStringForDBNulls(string strCheckString)
{
if(strCheckString.Trim() != string.Empty)
return strCheckString.Trim();
else
return DBNull.Value;
}

Could you please let me know what I am doing wrong? This is used to check the parameter being added, if it contains nothing, the make the value DBNull.Value, or use the value of thr string.

Thanks
BRENDAN

-- modified at 5:46 Thursday 20th October, 2005

Dead Skin Mask20-Oct-05 0:13

Dead Skin Mask

20-Oct-05 0:13

the return type of this method is DBNull, so you can only ever return a null value..
i suspect you don't really need a static method to perform this check, and could probably get away with something like this instead :

if(string.IsNullOrEmpty(strCheckString))<br />
    object = DBNull.Value;<br />
else<br />
    object = strCheckString;

Brendan Vogt20-Oct-05 0:40

20-Oct-05 0:40

I want to put this into a function because I have a 20 checks, and the code can get very long.

Please put the above mentioned code in a function.

Dead Skin Mask20-Oct-05 1:28

Dead Skin Mask

20-Oct-05 1:28

I don't know how well it would work but you could try making your method return Object

Brendan Vogt20-Oct-05 2:16

AudioVideoPlayback: Video as texture. Unable to Dispose()

20-Oct-05 2:16

This was how I initially had it, I just thought there might be another way. But thanks for your help, I appreciate it!!

Pixinger7719-Oct-05 23:15

Pixinger77

19-Oct-05 23:15

Hi,

During the last days i strugled around with a strange problem.
I need to play an video on a 3D-Object. That doesnt sound that hard. I created an device as common, added some data to the vertex buffer and activated the texture support of the Video Class:

video.TextureReadyToRender += new TextureRenderEventHandler(video_TextureReadyToRender);<br />
video.RenderToTexture(device);

Immediatly after the RenderToTexture call, the TextureReadyToRender Event was fired and I was able to render my desired scene. So far so goo, no problems at all. It works absolut perfectly Big Grin | :-D

But when I want to close my application I'm not able to clean up. Everytime when me (or the framework) wants to call the Dispose() method, an NullReferenceException is throwed.

I googled around a lot but couldn't find an answer. Does someone know perhaps an easy example? I tried to work with the Example from MDX-SDK(Summer2004), but because of the complicated framework structure I wasn't able to figure out too much. Does anyone have the same problem? D'Oh! | :doh:

XML File encryption

rmedo19-Oct-05 22:49

rmedo

19-Oct-05 22:49

Hi all,

I want to know how can i encrypt the whole XML file, it means that the data inside this file can't be understood with any user if he try to open this file (Ex.112364896fgdf64965)
if anyone know please help me Smile | :)

Guffa19-Oct-05 23:35

Guffa

19-Oct-05 23:35

Take a look at the System.Security.Cryptography namespace.

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rmedo23-Oct-05 2:03

rmedo

23-Oct-05 2:03

Hi,
i saw this namespace and i didn't found what i want , it makes only encryption for XMLElements and i want to incrypt the whole file to be in octet stream

Thanks for your help

Guffa24-Oct-05 21:24

Guffa

24-Oct-05 21:24

There is no special method for encrypting an xml document. Just get the xml document as a string, and encrypt it.

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