Directly referencing a control based on a string

  • Thread starter Thread starter Tamarack
  • Start date Start date
T

Tamarack

I have a simple function which loops through all the controls on a form
searching for a specific one:

Public Function FindControl(ByVal ctrls As Control.ControlCollection,
ByVal ctrlName As String) As Control

For Each ctrl As Control In ctrls
If ctrl.Name = ctrlName.Trim Then
Return ctrl
End If
If ctrl.HasChildren Then
FindControl(ctrl.Controls, ctrlName)
End If
Next
Return Nothing
End Function

But how do I reference that control's properties simply by knowing it's
name? The results of the looping function above allows me to work with a
strongly typed object so I can directly reference the properties because it
finds the object given the name. But it is extremely inefficient. What I'm
trying to do is exactly what you can do with an ADO recordset where you
refer to a specific field by it's name:

myRecordset("txtFirstName") = "Robert"

I would like to do the same thing with the Controls collection of a given
form:

myForm.Controls("txtFirstName").Text = "Robert"

Of course this is not allowed in .Net but I'm trying to find the equivalent.
Basically, I need to refer to a control directly by using its name instead
of looping through all the controls to find one that matches the name I
already know.

I know it's a little confusing and I'm probably not explaining it very well,
but thanks for any assistance.

Thanks,
Tamarack
 
Tamarack said:
I have a simple function which loops through all the controls on a
form searching for a specific one:

Public Function FindControl(ByVal ctrls As
Control.ControlCollection,
ByVal ctrlName As String) As Control

For Each ctrl As Control In ctrls
If ctrl.Name = ctrlName.Trim Then
Return ctrl
End If
If ctrl.HasChildren Then
FindControl(ctrl.Controls, ctrlName)
End If
Next
Return Nothing
End Function

But how do I reference that control's properties simply by knowing
it's name? The results of the looping function above allows me to
work with a strongly typed object so I can directly reference the
properties because it finds the object given the name. But it is
extremely inefficient. What I'm trying to do is exactly what you can
do with an ADO recordset where you refer to a specific field by it's
name:

myRecordset("txtFirstName") = "Robert"

I would like to do the same thing with the Controls collection of a
given form:

myForm.Controls("txtFirstName").Text = "Robert"

Of course this is not allowed in .Net but I'm trying to find the
equivalent. Basically, I need to refer to a control directly by using
its name instead of looping through all the controls to find one that
matches the name I already know.

I know it's a little confusing and I'm probably not explaining it
very well, but thanks for any assistance.
Click to expand...

You explained it very well.

First, /why/ do you need the name? Names are used at design time as
expressive names for the programmer and are resolved at compile time but
shouldn't matter at runtime. The compiler can not find misspelled names
placed in Strings. You'd get a runtime error.

Despite: you could use a modified version of the loop above and add each
found control to a Hashtable. The items in the Hashtable (= the controls)
can be accessed by their names. The loop can run once.


--
Armin

How to quote and why:
http://www.plig.net/nnq/nquote.html
http://www.netmeister.org/news/learn2quote.html
 
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