hi guys,

I am using Visual Studio 2005 and ASP.NET 2.0 and SQL Server Express 2005
Ok I've come up with the next problem:

I want to check if a field has a value and if it has it should display it, otherwise it shoudn't. Now In my database I've got fields wich have the Nulls allowed properties.These fields will have the initial value of NULL and when I erase the NULL value it will have no value.
So Im using the next statements to check this:

<%#IIf(IsDBNull(DataBinder.Eval(Container.DataItem , "Adreslijn2")) , "" , DataBinder.Eval(Container.DataItem, "Adreslijn2") & "<BR />")%>
This will work if the field has the initial NULL value but if it has no value or a value, both ways it will give no error but it will still print the breakline even if it has an empty value because it is not NULL ofcourse while it also shouldn't print the breakline if it has an empty value.

<%#IIf(DataBinder.Eval(Container.DataItem, "Adreslijn2") = ""), "" , DataBinder.Eval(Container.DataItem, "Adreslijn2") & "<BR />")%>
This will work if the field has no value (so when I have erased the initial NULL value) but when the field still has the initial NULL value it will give the following error:
Operator '=' is not defined for type 'DBNull' and string "".
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: Operator '=' is not defined for type 'DBNull' and string "".
Using OR in the IIF line of course also does not work because it will still give the error when the field contains the NULL value
Does anyone here know a solution for this? Is it maybe possible to give my fields in my database an initial empty value instead of NULL so when a new record is created it will fill the empty records with no value instead of NULL or is there another solution to this?


Thanks in advance

__________________
Venkat
knowledge is Power

Hi venkat,

Try using
<%#IIf(String.IsNullOrEmpty(DataBinder.Eval(Contai ner.DataItem, "Adreslijn2")) , "" , DataBinder.Eval(Container.DataItem, "Adreslijn2") & "<BR />")%>

__________________
H2O

Without us, no one can survive..

hi H2o,

Thanks for trying to help but I've tried it and it doesn't work when the value of the field is NULL
I get this error:
Conversion from type 'DBNull' to type 'String' is not valid.
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: Conversion from type 'DBNull' to type 'String' is not valid.
I think I should have to construct something like IF (thedataitem is DBNull) THEN do action ELSE IF (the dataitem is empty) THEN do action ELSE do other action... but I have no idea how to do that inside a repeater using IIF...

__________________
Venkat
knowledge is Power

hi,

OK... try this...
<%#IIf(IsDBNull(DataBinder.Eval(Container.DataItem , "Adreslijn2")) OrElse String.IsNullOrEmpty(DataBinder.Eval(Container.Dat aItem, "Adreslijn2")) , "" , DataBinder.Eval(Container.DataItem, "Adreslijn2") & "<BR />")%>

__________________
H2O

Without us, no one can survive..

hi,

That's it! Works like new

Thanks alot

__________________
Venkat
knowledge is Power

hi,

No worries!!
I think you might be getting confused here!! There aren't any "IIF functions" as you describe them.
IIF is a function which compacts a normal
IF condition THEN
condition_is_true_value
ELSE
condition_is_false_value
END IF
into 1 line... so really it's about understanding how the 3 component parts work... and getting your logic right!!
So in your case with IIf(condition, true_value, false_value) you're comfortable with the true_value and false_value, but not building the condition itself.
Well the condition can be any VB you want... in this case you could've written your own function that checks to see if the value is DBNull or String.Empty and then returns a Boolean... and then called that.
Instead I put the logic inline for you with judicious use of OrElse... this is something that is very important to understand...
statement1 And statement2 - this means that both statement1 and statement2 will be evaluated and both must be true
statement1 Or statement2 - this means that both statement1 and statement2 will be evaluated and either one must be true
statement1 AndAlso statement2 - this means that both statement1 and statement2 must be true, but if statement1 is false statement2 is not evaluated
statement1 And statement2 - this means that either statement1 or statement2 must be true, but if statement1 is true statement2 is not evaluated
Hope this all makes sense!

__________________
H2O

Without us, no one can survive..

I have one doubt....can we use the same
DataBinder.Eval Method for HTML controls with runnat="server"

Are you defining the name of your checkbox explicitly? It is not enough to The Repeater control renders a read-only list from a set of records returned from a data source. Like the FormView control, the Repeater control does not

what are the differences between property and local variable in

C#???

The Local variable defined inside the class adds up to the state

definition of the object during runtime, So when I say any object is in

valid state I necessarily mean that every member/local field of the class

has it's value in the desired and appropriate state. A property is the

interface provided for the outside world to access any particular field of

the class to manipulate the object state in the controlled way.

That's why it's the standard practice to encapsulate the public fields

through the properties. The properties can control the access to internal

fields through the get and set functions, you can choose to implement any

one or both the functions in order to control the access based on the

requirement.

Apart from the controlled access and security the properties also offer

another major advantage over the public field like, say if any exception is

raised when setting any particular field the field may be left in the

invalid state, where as if any exception occurs while accessing the field

through the property the old value is retained automatically there by

laving the encapsulated field in the valid state even though the exception

occurs.

__________________
A.Rajesh Khanna

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