Access to form controls in classes

Question

I'm new to C# programming, and I have a simple question. Let's say I have a form that contains several controls, perhaps a couple of text boxes and a combo box. Next, I have a class that contains methods to 'do something' with the controls on the form. Is this possible, and if so, how do I referrence the controls from the class?

Sam Hobbs · Answer

One way to do it is to create a function in your form class that loads the combobox from a DataTable. In other words, the function takes a DataTable as an argument. Then call the function in the form from the other class.

Manikavelu Velayutham · Answer

you cant access the controls in the seperate class. do it like below. public DataTable CmbItems() { string cSQLSelect = @"SELECT * FROM MyTable" ; SqlConnection cn = new SqlConnection (GetConnString()); *** this method not included for clarity SqlDataAdapter da = new SqlDataAdapter (cSQLSelect, cn); DataSet ds = new DataSet (); da.Fill(ds, "Table" ); DataTable dt = ds.Tables[ "Table" ]; return dt; } next you need to call this function in your form....for example you mentioned the class name as MyData. MyData objData = new MyData(); DataTable dt = objData.cmbItems(); foreach ( DataRow dr in dt.Rows) { cmbMyComboBox.items.add(...) } Like that you can continue. If this post really helped you, please mark it as accepted answer.

Ron · Answer

Manikavelu - Perhaps I should explain in greater detail the problem I'm trying to solve. I have a combo box on a form and I'd like to add/update the items from a table. To do this I've written a class method: class My Data { private void CmbItems () { string cSQLSelect = @"SELECT * FROM MyTable" ; SqlConnection cn = new SqlConnection (GetConnString()); *** this method not included for clarity SqlDataAdapter da = new SqlDataAdapter (cSQLSelect, cn); DataSet ds = new DataSet (); da.Fill(ds, "Table" ); DataTable dt = ds.Tables[ "Table" ]; foreach ( DataRow dr in dt.Rows) { cmbMyComboBox.items.add(...) } This is where I was hoping to have access to the combo box. The control is unknown to Intellisense, and therefore is not available to my class code. I've tried changing the combo box from private to public, but that did not work either. What am I doing wrong?

Ron · Answer

Thanks for your response. I'll try it out.

Manikavelu Velayutham · Answer

you can write a public property for those controls to retrieve the values and to assign the values. After that you can get or set the values for that control from your class. public string Category { get { return textbox1.Text ; } set { textbox1.Text = value ; } }

Access to form controls in classes

Answers (5)