Create C# controls names at runtime

[Matt]

Hi all,

I'm trying to create a system where it reads a number of records from
a database and then creates a row in the GUI that contains a single
field from the database and a button that has a reference to the
record. This way, once the task has been accomplished, the button can
be pressed next to the field and a time-stamp is placed into the
database.

Can anyone point me in the direction of either a tutorial or
documentation that may help me achive this?

Thanks,

Matt

 

[Fred Mellender]

I'm not sure I understand your question, but perhaps this will help:

I suggest you create the button and text statically, in the GUI builder.
Then study the code it generated in form.designer.cs. Copy that code (with
obvious modifications) to your application to dynamically create the
controls as triggered by your application logic.

 

[Matt]

I'm not sure I understand your question, but perhaps this will help:

I suggest you create the button and text statically, in the GUI builder.
Then study the code it generated in form.designer.cs. Copy that code (with
obvious modifications) to your application to dynamically create the
controls as triggered by your application logic.

Fred,

Thanks for the reply, I'll try and explain a bit better!

Basically, what I want to end up with is a grid as follows:

ROW1 description of task [button1]
ROW2 description of task [button2]
ROW3 description of task [button3]
....

Ideally, what I'd like to do is name the button after the task id from
the database. I've just discovered that I can rename buttons on the
fly, so I think that the following may work:

Button btn = new Button();
btn.name = dr[0]; // set the button name to the first column in the
data row

the question is, how do I then create the function to fire the data
into the database?

Matt.

 

[Matt]

I'm not sure I understand your question, but perhaps this will help:

I suggest you create the button and text statically, in the GUI builder.
Then study the code it generated in form.designer.cs. Copy that code (with
obvious modifications) to your application to dynamically create the
controls as triggered by your application logic.

Fred,

Thanks for the reply, I'll try and explain a bit better!

Basically, what I want to end up with is a grid as follows:

ROW1 description of task [button1]
ROW2 description of task [button2]
ROW3 description of task [button3]
...

Ideally, what I'd like to do is name the button after the task id from
the database. I've just discovered that I can rename buttons on the
fly, so I think that the following may work:

Button btn = new Button();
btn.name = dr[0]; // set the button name to the first column in the
data row

the question is, how do I then create the function to fire the data
into the database?

Matt.

OK, I now have the data being red into a datarow which then creates
the row for a tableLayoutPanel to allow me to adjust the rows etc.

The code I currently have for the tableLayoutRow is as follows:

foreach (DataRow dr in dra)
{

// create the label
Label taskDesc = new Label();
taskDesc.Width = 500;
// create the button
Button btn = new Button();
btn.Text = "Complete Task";
btn.Name = "btn"+dr[0].ToString();
MessageBox.Show("Btn name = " + btn.Name);
taskDesc.Text = dr[1].ToString();
tlop.Controls.Add(taskDesc,0,i);
//tlop.Controls.Add(btn+dr[0].ToString(),1,i);
i++;
}

Where tlop is the tableLayoutPanel The issue I am having is when it
comes to adding the button to the panel (the commented out line) I get
an error that I cannot convert an object to a control. The variable
is showing up as btn1, btn2 etc but I can't read it into the tlop!

Help!

Matt

 

[Fred Mellender]

The Add function does not want the name of the button, but the button
itself, as in:

Controls.Add(btn);

To add the function that handles the click event, first code the function in
the form's class. Suppose its name is "myClick". Then after you create the
button, add the code:

btn.Click += new System.EventHandler(myClick);

again, if you study the code generated by VS, you will see code for your
statically defined controls that you can use as a template.

 

[Matt]

The Add function does not want the name of the button, but the button
itself, as in:

Controls.Add(btn);

To add the function that handles the click event, first code the function in
the form's class. Suppose its name is "myClick". Then after you create the
button, add the code:

btn.Click += new System.EventHandler(myClick);

again, if you study the code generated by VS, you will see code for your
statically defined controls that you can use as a template.

OK, I now have the data being red into a datarow which then creates
the row for a tableLayoutPanel to allow me to adjust the rows etc.

The code I currently have for the tableLayoutRow is as follows:

foreach (DataRow dr in dra)
{

// create the label
Label taskDesc = new Label();
taskDesc.Width = 500;
// create the button
Button btn = new Button();
btn.Text = "Complete Task";
btn.Name = "btn"+dr[0].ToString();
MessageBox.Show("Btn name = " + btn.Name);
taskDesc.Text = dr[1].ToString();
tlop.Controls.Add(taskDesc,0,i);
//tlop.Controls.Add(btn+dr[0].ToString(),1,i);
i++;
}

Where tlop is the tableLayoutPanel The issue I am having is when it
comes to adding the button to the panel (the commented out line) I get
an error that I cannot convert an object to a control. The variable
is showing up as btn1, btn2 etc but I can't read it into the tlop!

Matt

Fred, that's great but how do I create the control in the first place
if the parameter for controls.add() changes with every row?

I understand the concepts of creating a button, I just don't know how
to create a button then name it dynamically.

 

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

Hi all,

I'm trying to create a system where it reads a number of records from
a database and then creates a row in the GUI that contains a single
field from the database and a button that has a reference to the
record. This way, once the task has been accomplished, the button can
be pressed next to the field and a time-stamp is placed into the
database.

Would it work for you having a button outside the listview ?
IMHO this is much easy to implement, faster to execute and do not use a lot
of buttons int he interface.

You could use the Tag property of the listviewitem to keep track of the
record in question:

foreach( DataRow row in GetRows.......)
{
ListViewItem lvi = new ...
lvi.Tag = row;
....
}

void TimeStamp_Onclick( ... )
{
DataRow row = (DataRow) listView1.Items[
listView1.SelectedIndices[0]].Tag;
}

 

[Fred Mellender]

Each button need not have a separate *variable* name used to create it.
I.E. you are creating one *new* button with the
Button btn = new Button();
each time you go through the loop. Just do all the work for that button
(using the "btn" variable) inside the loop. Once you add it via the
Controls.Add statement, one new button is attached to the form. When you
are done with the loop, you have created many new buttons, all via the
variable "btn" (which is different, conceptually, than the button's Name).

However, you may wish to clean up the buttons the next time through your
function (or, you can just let the gc collect them and it will call
Dispose()). In the former case, you should/could save the buttons as you
create them, in an array (declared (as a variable) in the Form class you are
creating):

List<Button> myButtons = null;

Then, just before you *enter* the loop:

if (myButtons != null)
{
foreach (Button myButton in myButtons)
myButton.Dispose();
}
myButtons = new List<Button>(10);

then inside the loop, in addition to your existing statements, place:
myButtons.Add(btn);

If you want to do something else with the buttons, outside the loop
(although I don't know why you would), you can get at them via the
"myButtons" variable.

The Add function does not want the name of the button, but the button
itself, as in:

Controls.Add(btn);

To add the function that handles the click event, first code the function
in
the form's class. Suppose its name is "myClick". Then after you create
the
button, add the code:

btn.Click += new System.EventHandler(myClick);

again, if you study the code generated by VS, you will see code for your
statically defined controls that you can use as a template.

OK, I now have the data being red into a datarow which then creates
the row for a tableLayoutPanel to allow me to adjust the rows etc.

The code I currently have for the tableLayoutRow is as follows:

foreach (DataRow dr in dra)
{

// create the label
Label taskDesc = new Label();
taskDesc.Width = 500;
// create the button
Button btn = new Button();
btn.Text = "Complete Task";
btn.Name = "btn"+dr[0].ToString();
MessageBox.Show("Btn name = " + btn.Name);
taskDesc.Text = dr[1].ToString();
tlop.Controls.Add(taskDesc,0,i);
//tlop.Controls.Add(btn+dr[0].ToString(),1,i);
i++;
}

Where tlop is the tableLayoutPanel The issue I am having is when it
comes to adding the button to the panel (the commented out line) I get
an error that I cannot convert an object to a control. The variable
is showing up as btn1, btn2 etc but I can't read it into the tlop!

Matt

Fred, that's great but how do I create the control in the first place
if the parameter for controls.add() changes with every row?

I understand the concepts of creating a button, I just don't know how
to create a button then name it dynamically.