如何使用Windows窗体使用同一事件的多种窗体？

Question

I asked this same question on SO-pt but no one seemed to understand the question, though I made it clear.

I have a form that I'll use to

1. Register customers in the database.
2. Alter any of the registers.
3. Show the registers.

Here I'm instantiating this form:

private void mnuRegister_Click(object sender, EventArgs e)
{
    var frmRegister = new frmRegisterScreen();
    frmRegister.Show();
}

As you can see, I'm calling the form from within a ToolStripMenuItem called mnuRegister .

Now, there are a number of properties from this form that I'm customizing at the Load` event, that'll make it more specific for registering the customers.

Below is the code:

private void frmRegisterScreen_Load(object sender, EventArgs e)
{
    //set the database connection and the Sql command to be used
    string conString = "Server = .\\sqlexpress; trusted_connection = yes; database=he_dados;";
    SqlConnection con = new SqlConnection(conString);

    string sel = "SET DATEFORMAT dmy;\n" //set date format to dd//mm/yyyy
                        + "Insert into Customer(" +
                         "Name,IDCard,Phone,Address,Observation)" +
                         "values(" +
                         "'" + txtName.Text +
                         "','" + mskIDCard.Text +
                         "','" + mskPhone.Text +
                         "','" + txtAddress.Text +
                         "','" + txtObs.Text + "');";    
    SqlCommand selCmd = new SqlCommand(sel, con);

    //set the form properties relate to the customer registration
    lblMain.Text = "Register Customer";
    tsbSave.Text = "Save Changes";
}

As you can see, this code is obviously intended to insert data in a table.

Now, what I want to do is to call another instance of this form:

private void mnuViewRegister_Click(object sender, EventArgs e)
{
    var frmViewRegister = new frmRegisterScreen();
    frmViewRegister.Show();
}

Then I want to set specific properties, required for me to make a simple query using the same form, for example:

private void frmRegisterScreen_Load(object sender, EventArgs e)
{
    //set the database connection and the Sql command to be used
    string conString = "Server = .\\sqlexpress; trusted_connection = yes; database=he_dados;";
    SqlConnection con = new SqlConnection(conString);

    string sel = "Select * from Customer;";    
    SqlCommand selCmd = new SqlCommand(sel, con);

    //set the form properties relate to the customer registration
    lblMain.Text = "View Customer Registers";
    tsbSave.Text = "View";
}

In other words, I would like to have event calls specific to the instance of the form, instead of having one event that's valid for any of the instances.

Is that possible?

Answer 1

If you find yourself configurating a great deal of UI elements, then just create separate Forms. It's not like they cost you anything, and they'll be easier to maintain. But it looks like you're only changing a couple of UI elements (like the label), so that's not too bad.

Either move the configuration logic into two separate methods on the Form, like ConfigureForRegistration and ConfigureForViewingRegistration , and then call the appropriate one when you instantiate the Form:

var frmRegister = new frmRegisterScreen();
frmRegister.ConfigureForRegistration();
frmRegister.Show();

Or you could create an enumeration for each possible view, and pass a value in when you instantiate the Form:

public enum ScreenOption
{
    Register,
    AlterRegister,
    ViewRegister
}

public class frmRegisterScreen
{
    public frmRegisterScreen(ScreenOption option)
    {
        switch (option)
        {
            case ScreenOption.ViewRegister:
                //set the database connection and the Sql command to be used
                string conString = "Server = .\\sqlexpress; trusted_connection = yes; database=he_dados;";
                SqlConnection con = new SqlConnection(conString);
                break;
            ...
        }
    }
}

var frmRegister = new frmRegisterScreen(ScreenOption.ViewRegister);
frmRegister.Show();