Dynamic casting

[Matt Weaver]

I'm trying to setup a sub that would assign the properties of a
webcontrol based on data in a table. I've setup a routine which looks
like this:

Private Sub SetObjectProper ty(ByRef obj As Object, _
ByValPropertyNa me As String, _
ByVal PropertyValue As String)
Dim wType As System.Type = obj.GetType
Dim wProp As Reflection.Prop ertyInfo = _
wType.GetProper ty(PropertyName )
wProp.SetValue( obj, PropertyValue, Nothing)
End Sub

It works well when the property is a string, but when it's boolean I get
this error: "Object of type 'System.String' cannot be converted to
type 'System.Boolean '"

I can get the type of the property (in this case, System.Boolean) , I
have the value I'd get if I used .ToString(). .NET has to have some
function that'd dynamically cast the string back to Boolean (or whatever
data type), right? I'm trying to avoid a giant if-then structure (if
type = system.boolean then cast as boolean).

TIA!
-Matt

[sloan]

I think you wrote it correct, but because of the way the eval works...
you'll have to hack in some case statements.

Here is my code... notice I check the "CanWrite". That probably isn't your
issue, but I list it there anyways.

I think you'll need to hack in some case statements on the type
unforunately.
'''''''''the next loop is basically a cloning mechanism.

''''''''Dim prop As PropertyInfo

''''''''For Each prop In AssemblyPropert ies

'''''''' If prop.CanWrite Then ' only update properties which can be written
to

'''''''' Dim indivReportProp erty As PropertyInfo =
newObject.GetTy pe().GetPropert y(prop.Name)

'''''''' If Not (indivReportPro perty Is Nothing) Then 'handle the case where
the objects are not perfect copies of one another

'''''''' 'this sets the "new object" property to the getvalue of the "old
object"

'''''''' indivReportProp erty.SetValue(n ewObject, prop.GetValue(n ewObject,
Nothing), Nothing)

'''''''' End If

'''''''' End If

''''''''Next prop



"Matt Weaver" <mw********@yah oo.com> wrote in message
news:ec******** ******@TK2MSFTN GP09.phx.gbl...

I'm trying to setup a sub that would assign the properties of a
webcontrol based on data in a table. I've setup a routine which looks
like this:

Private Sub SetObjectProper ty(ByRef obj As Object, _
ByValPropertyNa me As String, _
ByVal PropertyValue As String)
Dim wType As System.Type = obj.GetType
Dim wProp As Reflection.Prop ertyInfo = _
wType.GetProper ty(PropertyName )
wProp.SetValue( obj, PropertyValue, Nothing)
End Sub

It works well when the property is a string, but when it's boolean I get
this error: "Object of type 'System.String' cannot be converted to
type 'System.Boolean '"

I can get the type of the property (in this case, System.Boolean) , I
have the value I'd get if I used .ToString(). .NET has to have some
function that'd dynamically cast the string back to Boolean (or whatever
data type), right? I'm trying to avoid a giant if-then structure (if
type = system.boolean then cast as boolean).

TIA!
-Matt

[Karl Seguin [MVP]]

Well, you can use Convert.ChangeT ype(obj, type);

For situations like this, I often find it better to ass in a
NameValueCollec tion collection into the object, and let it figure out how to
do thing:

//pass the values using an interface:
((ISomeInterfac e)obj).Paramete rs = keyValueCollect ion;
//use the values:
if (Parameters["count"] != null)
{
_count = Int32.Parse(Par ameters["count"]);
}
else
{
throw new Exception("coun t parameter expected");
}
Karl

--
http://www.openmymind.net/
http://www.fuelindustries.com/
"Matt Weaver" <mw********@yah oo.com> wrote in message
news:ec******** ******@TK2MSFTN GP09.phx.gbl...

I'm trying to setup a sub that would assign the properties of a webcontrol
based on data in a table. I've setup a routine which looks like this:

Private Sub SetObjectProper ty(ByRef obj As Object, _
ByValPropertyNa me As String, _
ByVal PropertyValue As String)
Dim wType As System.Type = obj.GetType
Dim wProp As Reflection.Prop ertyInfo = _
wType.GetProper ty(PropertyName )
wProp.SetValue( obj, PropertyValue, Nothing)
End Sub

It works well when the property is a string, but when it's boolean I get
this error: "Object of type 'System.String' cannot be converted to type
'System.Boolean '"

I can get the type of the property (in this case, System.Boolean) , I have
the value I'd get if I used .ToString(). .NET has to have some function
that'd dynamically cast the string back to Boolean (or whatever data
type), right? I'm trying to avoid a giant if-then structure (if type =
system.boolean then cast as boolean).

TIA!
-Matt

[Matt Weaver]

Convert.ChangeT ype worked for me. I'll keep the rest of your message in
mind if it breaks with more complicated object types.

Karl Seguin [MVP] wrote:

Well, you can use Convert.ChangeT ype(obj, type);

For situations like this, I often find it better to ass in a
NameValueCollec tion collection into the object, and let it figure out how to
do thing:

//pass the values using an interface:
((ISomeInterfac e)obj).Paramete rs = keyValueCollect ion;
//use the values:
if (Parameters["count"] != null)
{
_count = Int32.Parse(Par ameters["count"]);
}
else
{
throw new Exception("coun t parameter expected");
}
Karl