每次加载表单时保持禁用按钮

Question

I have two forms ( Form1 and Form2 ).

Form1 has some other controls which are saved to the database after all the fields are filled. It also has a DELETE button where you can delete the searched information from the database and it has the "Available Rooms" button, which when clicked will load Form2 .

Form2 has a number of buttons (unoccupied rooms) which I can select from. Now, my problem is how to keep that selected button (eg.: 101) on Form2 disabled when I click on "Available rooms" for a second time, or any other day and also keep any other selected button (eg.: 102) disabled when Form2 loads the next time, etc.

To make it clear, the only time I want the disabled button on Form2 be active, is when I click on the DELETE button on Form1. But, this I cad do it.

Answer 1

When you are starting the new Form2, save the form variable and use it to access its values. You should be able to access the button.Enabled property of your button on Form2.

This is what your code on Form1

Form2 secondForm;

private void button_Clicked (object sender, EventArgs e)
{
    if (secondForm != null)
    {
        secondForm.yourButton.Enabled = true;
    }
    // Any other code you want to handle
}
private void Form2_Closing (object sender, EventArgs e)
{
    secondForm = null;
}

And this is what you should do everytime you open/show Form2:

secondForm = new Form2();
secondForm.Show();
secondForm.Closing += new System.EventHandler(Form2_Closing);

EDIT: Thanks Hans Passant! Forgot that. You should also set the value of secondForm to null if the form is closed. Edited the code above.

Answer 2

Use Form load event - https://msdn.microsoft.com/en-us/library/system.windows.forms.form.load(v=vs.110).aspx

When you load Form 2, read the database. You already know the condition when the button for the room needs to be disabled. For example, for simplicity let's assume that you can read a column of the database into ac# boolean(say unAvailable) and based on that you can make a decision whether the room is available. So on your form 2 load (handle Form load event) there needs to be a condition like -

Form_Load(System.Object sender, 
System.EventArgs e)
{
    roomButton.Enabled = unAvailable;
}

So based on the value of field unAvailabled the roomButton is enabled or disabled.

Answer 3

I must say thank you for all your comments and answers above. Going through them, my mind was opened to think differently particularly using the Form_Load event on Form2 and when did, it worked like a charm!!!!.

All I did on the Form2_Load event was to read the Apartment_No column(as per one contributor suggested) in the database, and use each of the values to disable the corresponding button using the switch... case.

Here is the code below:

     private void Form2_Load(object sender, EventArgs e)
    {
        string constr = @"Data Source=DESKTOP-J6KRI77\SQLEXPRESS; Initial Catalog = SELLnBUY; Integrated Security = true";
        string cmdstr = "SELECT Apartment_No FROM Apartment";
        SqlConnection con = new SqlConnection(constr);
        SqlCommand com = new SqlCommand(cmdstr, con);

        con.Open();
        SqlDataReader r = com.ExecuteReader();


        while (r.Read())
        {
          int room = int.Parse(r["Apartment_No"].ToString());

            switch(room)
            {
                case 101:               
                        button1.Enabled = false;
                        break;                       
                case 102:                       
                        button2.Enabled = false;
                        break;
                    case 103:
                        button3.Enabled = false;
                        break;
                case 104:
                        button4.Enabled = false;
                        break;

            }
        }
        con.Close();