Getting the value from a combobox

Scott Stewart

I need to get the text value from a combo box on one form to assign to a variable in a separate class. I tried
stName=frmParent.ActiveForm.Controls["tblStatesComboBox"].Text
That generated an error that said it was not associated with an object.

What is the proper syntax for reading control values in a separate form. My class is NOT a form. It is just a small class with several values and properties.

Thanks

7 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes14y ago
Accepted answer
If the combobox is within a form whose class name is frmParent and it has been placed directly on the form rather than a container such as a panel or groupbox, then you could get the value of its Text property as follows:

frmParent parent = (frmParent)Application.OpenForms("frmParent");
stName = parent.Controls["tblStatesComboBox"].Text;
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Scott Stewart14y ago
Now that worked. This time I ran it before getting to excited. Thank you again. You were a big help.
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Vulpes14y ago
Sorry, it's a mistake on my part.

It should be square brackets (for an indexer) rather than round brackets:

frmParent parent = (frmParent)Application.OpenForms["frmParent"];
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Scott Stewart14y ago
I got too enthusiastic in my last replay because nothing in the code page was underlined. But it didn't work. It tells me that OpenForms cannot be used like a method. It says "Non-Invocable member 'System.Windows.Forms.Application.OpenForms' cannot be used like a method. Iread the documentation for openfoms and it was brief but said it returns a collection of forms. What simple thing am I missing this time?
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Scott Stewart14y ago
YES!!!

I had added a property to my parent form so I could just "get" the StateName from the combobox. I just couldn't see it because, as you said, I didn't have the using directive at the top of my class.

Thank you for a clean, concise answer.
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Vulpes14y ago
You're probably getting the error when attempting to use the Application class because you don't have this 'using' directive in your class file:

using System.Windows.Forms;

You need to get a reference to the form before you can get access to its controls.

If the form is in fact the current active form, then an alternative way of getting it would be:

frmParent parent = (frmParent)Form.ActiveForm;

which is similar to what you were doing in the first place.

It's still possible to get at the combobox by first getting a reference to the toolstrip from the form's Controls collection and then getting a reference to the combobox from the toolstrip's Controls collection.

However, a more convenient way would be to create a public (or internal) read-only property within the form class which returns the combobox's Text property. All you need to do then is to invoke this property with your form reference.
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Scott Stewart14y ago
Ok. The combo box is actually in the toolstrip. Sorry I didn't say that in the first place. Why do you have to create a variable of frmParent type? When I tried the line you have I got an error on "Application" it kept wanting to make it ApplicationID or something else. It said the name does not exist in the current context.
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