set a nullable property in object

[Rick]

I have a business object (class) with some nullable properties declared like
this:

Private _MyProp as Nullable(of Int16)
public Property MyProp as Nullable(Of Int16)
get
Return _MyProp
end get
set(ByVal Value as Nullable(Of Int16))
If not _MyProp.Equals( value) then
_MyProp = Value
NotifyPropertyC hanged("MyProp" ) ' marks the property changed
end if
end set

I can read from my database with no problem for both MyProp's with or
without a value. When MyProp = 1 and I try to set it to Null in a Windows
TextBox, the form will not even let me move to another control. If I change
rows in a datagridview, the value is set back to 0.

So, I added an OnValidate event like this:

if String.IsNullOr Empty(myControl .Text) then _
myBusinessObjec t.MyProperty = Nothing

Now I can set the nullable property to "Nothing" and it works as expected.
My question is - Is this the normal procedure to set a nullable value or am
I missing some shortcut where I don't have to add the OnValidate event?

Rick

[PlatinumBay]

Re: set a nullable property in object

Rick,

I would imagine that the code is attempting to set the Nullable value to ""
when there is nothing in the textbox, which is not null. I don't see any
harm in overriding the OnValidate event with the code you have, to perform
the translation from Empty to Null.

Hope this helps.

Steve

"Rick" <RickREMOVETHIS @LakeValleySeed .comwrote in message
news:OzojkWUmHH A.4592@TK2MSFTN GP05.phx.gbl...

>I have a business object (class) with some nullable properties declared
>like this:
>
Private _MyProp as Nullable(of Int16)
public Property MyProp as Nullable(Of Int16)
get
Return _MyProp
end get
set(ByVal Value as Nullable(Of Int16))
If not _MyProp.Equals( value) then
_MyProp = Value
NotifyPropertyC hanged("MyProp" ) ' marks the property changed
end if
end set
>
I can read from my database with no problem for both MyProp's with or
without a value. When MyProp = 1 and I try to set it to Null in a Windows
TextBox, the form will not even let me move to another control. If I
change rows in a datagridview, the value is set back to 0.
>
So, I added an OnValidate event like this:
>
if String.IsNullOr Empty(myControl .Text) then _
myBusinessObjec t.MyProperty = Nothing
>
Now I can set the nullable property to "Nothing" and it works as expected.
My question is - Is this the normal procedure to set a nullable value or
am I missing some shortcut where I don't have to add the OnValidate event?
>
Rick
>

[Tim Van Wassenhove]

Re: set a nullable property in object

Rick schreef:

Now I can set the nullable property to "Nothing" and it works as expected.
My question is - Is this the normal procedure to set a nullable value or am
I missing some shortcut where I don't have to add the OnValidate event?

I prefer to do it at Parsing time...

this.myDataSour ce = new MyDataSource();
this.textBox1.D ataBindings.Add ("Text", this.myDataSour ce, "Double",
true);
this.textBox1.D ataBindings["Text"].Parse += this.Text_Parse ;

void Text_Parse( object sender, ConvertEventArg s e )
{
if( e.Value == null || e.Value.ToStrin g().Length == 0 )
{
e.Value = null;
}
}


--
Tim Van Wassenhove - Read my mind <url:http://www.timvw.be/>