Re: How do i check if an object can be cast to a valid SQLDbType? - C# Discussion Boards

Re: How do i check if an object can be cast to a valid SQLDbType?

20-Jul-06 22:39

I have a method that accepts an SQLDbType and an object.
I would like it the check if that object can be cast into the SQLDbType.
like so:

<br />
public void Thingy(SqlDbType dataType, object value)<br />
    {<br />
        if (/*CHECK value can be cast to datatype ???*/)<br />
        {<br />
           //Do this<br />
        }<br />
        else<br />
        {<br />
           //Complain<br />
        }<br />
    }<br />

How would i go about doing this ?

Thanks.

Robert Rohde20-Jul-06 22:46

Re: How do i check if an object can be cast to a valid SQLDbType?

20-Jul-06 22:46

Hi,

if (value is SqlDbType) {
   //Do this
}

Red_Wizard_Shot_The_Food20-Jul-06 23:24

Re: How do i check if an object can be cast to a valid SQLDbType? [modified]

20-Jul-06 23:24

Thanks

,
My next questions is:
So how then would I cast it to the specific data type of dataType (passed as a method argument/parameter)?

<br />
(dataType(value))

does not seem to work

nor does

<br />
(SQLDbType.dataType(value)) <br />

Cheers.

Martin#20-Jul-06 23:41

Martin#

20-Jul-06 23:41

Hello,

<code>
public SqlDbType ConvertObjectToSqlDbType(object o)
{
return o as SqlDbType;
}

{
Object myobject = ????;
SqlDbType myvalue = ConvertObjectToSqlDbType(myobject)
if(myvalue!=null)
{
//Use it!
}
}

</code>

Hope that helps you.

All the best,

Martin

-- modified at 5:46 Friday 21st July, 2006

Re: How do i check if an object can be cast to a valid SQLDbType?

Robert Rohde20-Jul-06 23:52

Re: How do i check if an object can be cast to a valid SQLDbType?

20-Jul-06 23:52

This won't function because SqlDbType is a value type.

Red_Wizard_Shot_The_Food20-Jul-06 23:53

Re: How do i check if an object can be cast to a valid SQLDbType?

20-Jul-06 23:53

Sorry if im not understanding what your getting at but what i want to do is pass an SQLDataType (like varchar or bigint) and an object then if the value castable to that type then cast it.

so value does not become just SQLDbType it becomes SQLDbType.bigint if the values passed where like so:

myMethod(SQLDataType.bigint, "400893");

or a varchar if you did this:

myMethod(SQLDataType.varchar, "ScoobyDoo");

I hope that makes sence (and is possible??)

Thanks again.

Robert Rohde20-Jul-06 23:54

Re: How do i check if an object can be cast to a valid SQLDbType?

20-Jul-06 23:54

If you have checked whether value is really of type SqlDbtype the following is safe to use:

SqlDbType type = (SqlDbType)value;

Red_Wizard_Shot_The_Food21-Jul-06 0:00

Re: How do i check if an object can be cast to a valid SQLDbType?

21-Jul-06 0:00

Robert Rohde wrote:
If you have checked whether value is really of type SqlDbtype the following is safe to use:

SqlDbType type = (SqlDbType)value;

Sorry if im getting the wrong end of the stick here...

But that code looks like is alters the value of type to = the value of value cast to an SQLDbType.

What I'm after is value to be cast from an object to the SQLDbType described by dataDype in the argument.

Or is that what it does do and I'm just misunderstanding the code.

-- modified at 6:02 Friday 21st July, 2006

Robert Rohde21-Jul-06 0:21

Re: How do i check if an object can be cast to a valid SQLDbType?

21-Jul-06 0:21

No I don't get what you try to do Smile | :)

.
The dataType parameter isn't a Type. Its a concrete value which is one of the values of the SqlDbType enumeration. What do you want to do with the object after being 'casted'. Probably then I understand what you actually are trying to do...

Red_Wizard_Shot_The_Food21-Jul-06 0:29

Re: How do i check if an object can be cast to a valid SQLDbType?

21-Jul-06 0:29

Here is a more fleshed out version... its part of an SQL "helper" type class this method is for adding parameters:

public void AddParameter(string name, SqlDbType dataType, object value)
{
if (name[0] != '@')
name.Insert(0,"@");

_SQLcmd.Parameters.Add(new SqlParameter(name, dataType));
_SQLcmd.Parameters[name].Value = value;
}

This works (well it compiles) but I want an IF clause in there so it only tries the last 2 lines IF the "value" object is castable to the SQLDbType defined by dataType.

Hope that helps.

And thanks again.

Robert Rohde21-Jul-06 1:11

Re: How do i check if an object can be cast to a valid SQLDbType?

21-Jul-06 1:11

Hi again,

ok now I understand. I think you will have to make a swtich and test it for each type separately. At least I don't know any other way to do it.
You should also correct your Insert call:

if (name[0] != '@')
   name = name.Insert(0,"@");

Insert doesn't change the instance name (because string is immutable) but returns a new instance.

Andrei Ungureanu20-Jul-06 22:47

Andrei Ungureanu

20-Jul-06 22:47

hy,
one of the ways you can achieve that is to use exceptions, like this

try
{
//do the cast
}
catch(Exception)
{
//complain
}

using Exception in catch you catch all the exceptions that can occur. Of course you can only catch the InvalidCastException but that's your choice.
Hope it helps.

Do your best to be the best

Drag drop to usercontrol from toolbox

Piovra_20-Jul-06 22:03

Piovra_

20-Jul-06 22:03

Hi,

I have created a simple usercontrol which holds a panel. I drag this self made control to a window form. What i would like is to drag items from the toolbox to this usercontrol. i.e. drag a textbox to the panel on the usercontrol. But this is not working, the textbox is added to the window form instead of the panel from the user control.

So how can i make this happen why does the panel loose it's ability to add items that a dragged from the toolbox once the panel is part of a user control. Note i want to make the drag/drap happen at design time so just like it works normally.

Re: Drag drop to usercontrol from toolbox

Nader Elshehabi20-Jul-06 22:25

Nader Elshehabi

20-Jul-06 22:25

Hello

Usercontrols don't handle drag/drop events by themselves. You have to do it maually and check the DesignMode boolean value to see if this drag/drop event is at design time or at run time.

Also there is Control.ControlsAdded event which you might want to handle as well

A better approach -if it doesn't contraindicate your goal from the control- is to inherit it from another Control similar to yours -eg. MenuStrip, ToolStrip, StatusStip, ToolStripContainer, etc..- Then it'll take care of everything for you. You just have to add a final touch to the code

Regards Rose | [Rose]

How to Intercept a number when a call comes thru ? [modified]

Trance Junkie20-Jul-06 21:47

Trance Junkie

20-Jul-06 21:47

Hi everyone Smile | :)

I was thinking is it possible to develop a application in c# that can intercept a telephone number using a dialup modem every time a phone call comes thru answered or unanswered the app should be able to log the number.

Thanks in Advance!
Smile | :)

-- modified at 3:48 Friday 21st July, 2006

Re: How to Intercept a number when a call comes thru ?

stancrm21-Jul-06 2:44

stancrm

21-Jul-06 2:44

I think you can start to search there:
http://www.codeproject.com/useritems/IVR.asp

graph in reporting services

cellardoor071620-Jul-06 21:28

cellardoor0716

20-Jul-06 21:28

i know that this question doesn´t belong here, but i always get perfect answers here.

i´m working with reporting services and i have to make some graphs and i really don´t know how. there are only 2 report types - tabular and matrix. i also have problem with drill down option when using matrix, it´s not working correctly, i mean it´s hiding rows and columns, but it´s not sumarizing values.

cellardoor

cellardoor

Re: graph in reporting services

Andrew Rissing21-Jul-06 4:38

Andrew Rissing

21-Jul-06 4:38

It seems you forgot to post the question. You've got the problem but no question Wink | ;-)

How can I compare doubles?

xkx3220-Jul-06 21:28

xkx32

20-Jul-06 21:28

hello

can you tell me how can I compare two double vars in my app

i tried:

if (var.Equals(.4))

but it's not working... and i am sure the two var contains the same value (i used MessageBox to print the vals)

please help me

Nader Elshehabi20-Jul-06 22:10

Nader Elshehabi

20-Jul-06 22:10

Hello

the Equals() method is usually used to compare two reference types -Yet it still can compare value types-.
Instead you should take a shorter approach in comparing two value types by using the == operator

double A = 5.4;
double B = 2.3;

if (A == B)
    {
    //Do something
    }
else if(A == 2.7)
    {
    //Do somthing
    }

Regards

Andrei Ungureanu20-Jul-06 22:42

Andrei Ungureanu

20-Jul-06 22:42

hy,
have you tried to compare something like:

double a;
double b;

if (a <= b)
{ }
if (a >= b)
{ }

it works just fine with double as with integers.

Do your best to be the best

Shajeel21-Jul-06 0:35

Shajeel

21-Jul-06 0:35

may be a better way to compare double will be

if(Math.Abs(var-0.4) < 1e-14)

Regards
Shajeel