How to extract the value of dynamically generated controls?

Question

hi friend,
how to extract the value of dynamically generated controls and generates SQL statements.
you can download attachments view, it provides a detailed description.

Let me be clear, this program is designed to meet the user complex query.
thank very much.

Vulpes · Answer

I wouldn't use a configuration file for this - a simple text file, stored in the application folder, will suffice. Also you'll need to store the state of the controls (if the checkbox is checked) when the form closes rather than when the checkbox's checked state changes. Taking these points into account, I'd try adding the following code (the 'skeleton' handlers for the form's Load and FormClosed events should of course be added from the VS designer rather than manually): using System.IO; // .... private void Form1_Load(object sender, EventArgs e) { string path = Application.StartupPath + "\dynamic_controls.txt"; if (File.Exists(path)) { using (StreamReader sr = new StreamReader(path)) { int cLeft_Old = int.Parse(sr.ReadLine()); btnAddControls.PerformClick(); ComboBox cb1 = (ComboBox)this.Controls["1/cb1"]; ComboBox cb2 = (ComboBox)this.Controls["1/cb2"]; TextBox tb2 = (TextBox)this.Controls["1/tb2"]; cb1.SelectedIndex = int.Parse(sr.ReadLine().Split(',')[1]); cb2.SelectedIndex = int.Parse(sr.ReadLine().Split(',')[1]); tb2.Text = sr.ReadLine().Split(',')[1]; ComboBox cb3 = null; for (int i = 2; i { btnAddControls.PerformClick(); cb1 = (ComboBox)this.Controls[i.ToString() + "/cb1"]; cb2 = (ComboBox)this.Controls[i.ToString() + "/cb2"]; cb3 = (ComboBox)this.Controls[i.ToString() + "/cb3"]; tb2 = (TextBox)this.Controls[i.ToString() + "/tb2"]; cb1.SelectedIndex = int.Parse(sr.ReadLine().Split(',')[1]); cb2.SelectedIndex = int.Parse(sr.ReadLine().Split(',')[1]); cb3.SelectedIndex = int.Parse(sr.ReadLine().Split(',')[1]); tb2.Text = sr.ReadLine().Split(',')[1]; } } } } private void Form1_FormClosed(object sender, FormClosedEventArgs e) { string path = Application.StartupPath + "\dynamic_controls.txt"; if (File.Exists(path)) File.Delete(path); if (checkBox1.Checked && cLeft > 1) { using (StreamWriter sw = new StreamWriter(path)) { sw.WriteLine(cLeft); ComboBox cb1 = (ComboBox)this.Controls["1/cb1"]; ComboBox cb2 = (ComboBox)this.Controls["1/cb2"]; TextBox tb2 = (TextBox)this.Controls["1/tb2"]; WriteComboBoxToFile(cb1, sw); WriteComboBoxToFile(cb2, sw); WriteTextBoxToFile(tb2, sw); ComboBox cb3 = null; for (int i = 2; i { cb1 = (ComboBox)this.Controls[i.ToString() + "/cb1"]; cb2 = (ComboBox)this.Controls[i.ToString() + "/cb2"]; cb3 = (ComboBox)this.Controls[i.ToString() + "/cb3"]; tb2 = (TextBox)this.Controls[i.ToString() + "/tb2"]; WriteComboBoxToFile(cb1, sw); WriteComboBoxToFile(cb2, sw); WriteComboBoxToFile(cb3, sw); WriteTextBoxToFile(tb2, sw); } } } } // helper methods private void WriteComboBoxToFile(ComboBox cb, StreamWriter sw) { sw.Write(cb.Name); sw.Write(","); sw.WriteLine(cb.SelectedIndex); } private void WriteTextBoxToFile(TextBox tb, StreamWriter sw) { sw.Write(tb.Name); sw.Write(","); sw.WriteLine(tb.Text); } Incidentally, I've just noticed a small mistake in my previous post: if (cb3.SelectedIndex == -1) { MessageBox.Show("Nothing yet selected in the third combobox"); cb3. Focus(); return; }

Vulpes · Answer

Try the following. In order to identify dynamic controls, you'll need to set their Name properties which I've done. It's also useful to set their Tag property so you can quickly tell which ones have been added dynamically when it comes to removing them. I've assumed for now that if the values need to be surrounded by single quotes (because they're strings or dates), then the user will include these in the textbox(es): private void btnAddControls_Click(object sender, EventArgs e) { if (cLeft >= 2) { ComboBox cb1 = new ComboBox(); cb1.Name = cLeft.ToString() + "/cb1"; cb1.Tag = "dynamic"; cb1.Top = cLeft * cTop; cb1.Left = 20; cb1.Items.Add("AND"); cb1.Items.Add("OR"); cb1.Width = minWidth; this.Controls.Add(cb1); ComboBox cb2 = new ComboBox(); cb2.Name = cLeft.ToString() + "/cb2"; cb2.Tag = "dynamic"; cb2.Top = cLeft * cTop; cb2.Left = 100; cb2.Width = maxWidth; cb2.Items.Add("Field1"); cb2.Items.Add("Field2"); cb2.Items.Add("Field3"); cb2.Items.Add("Field4"); this.Controls.Add(cb2); ComboBox cb3 = new ComboBox(); cb3.Name = cLeft.ToString() + "/cb3"; cb3.Tag = "dynamic"; cb3.Top = cLeft * cTop; cb3.Left = 210; cb3.Width = minWidth; cb3.Items.Add(">"); cb3.Items.Add(" cb3.Items.Add("!="); cb3.Items.Add("="); cb3.Items.Add("like"); this.Controls.Add(cb3); TextBox tb2 = new TextBox(); tb2.Name = cLeft.ToString() + "/tb2"; tb2.Tag = "dynamic"; tb2.Top = cLeft * cTop; tb2.Left = 290; tb2.Text = "Value" + cLeft.ToString(); tb2.Width = maxWidth; this.Controls.Add(tb2); cLeft += 1; } else { ComboBox cb1 = new ComboBox(); cb1.Name = "1/cb1"; cb1.Tag = "dynamic"; cb1.Top = cLeft * 50; cb1.Left = 100; cb1.Width = maxWidth; cb1.Width = maxWidth; cb1.Items.Add("Field1"); cb1.Items.Add("Field2"); cb1.Items.Add("Field3"); cb1.Items.Add("Field4"); this.Controls.Add(cb1); ComboBox cb2 = new ComboBox(); cb2.Name = "1/cb2"; cb2.Tag = "dynamic"; cb2.Top = cLeft * 50; cb2.Left = 210; cb2.Width = minWidth; cb2.Items.Add(">"); cb2.Items.Add(" cb2.Items.Add("!="); cb2.Items.Add("="); cb2.Items.Add("like"); this.Controls.Add(cb2); TextBox tb2 = new TextBox(); tb2.Name = "1/tb2"; tb2.Tag = "dynamic"; tb2.Top = cLeft * 50; tb2.Left = 290; tb2.Text = "Value" + cLeft.ToString(); tb2.Width = maxWidth; this.Controls.Add(tb2); cLeft += 1; } } private void btnGeneratesSQL_Click(object sender, EventArgs e) { if (cLeft == 1) { MessageBox.Show("You haven't yet added any controls!"); btnAddControls.Focus(); return; } ComboBox cb1 = (ComboBox)this.Controls["1/cb1"]; ComboBox cb2 = (ComboBox)this.Controls["1/cb2"]; TextBox tb2 = (TextBox)this.Controls["1/tb2"]; if (cb1.SelectedIndex == -1) { MessageBox.Show("Nothing yet selected in the first combobox"); cb1.Focus(); return; } if (cb2.SelectedIndex == -1) { MessageBox.Show("Nothing yet selected in the second combobox"); cb2.Focus(); return; } if (tb2.Text.Trim().Length == 0) { MessageBox.Show("Textbox can't be empty"); tb2.Focus(); return; } string sql = "SELECT * FROM TableName WHERE 
" + String.Format("{0} {1} {2}", cb1.SelectedItem, cb2.SelectedItem, tb2.Text); if (cLeft > 2) { ComboBox cb3 = null; for (int i = 2; i { cb1 = (ComboBox)this.Controls[i.ToString() + "/cb1"]; cb2 = (ComboBox)this.Controls[i.ToString() + "/cb2"]; cb3 = (ComboBox)this.Controls[i.ToString() + "/cb3"]; tb2 = (TextBox)this.Controls[i.ToString() + "/tb2"]; if (cb1.SelectedIndex == -1) { MessageBox.Show("Nothing yet selected in the first combobox"); cb1.Focus(); return; } if (cb2.SelectedIndex == -1) { MessageBox.Show("Nothing yet selected in the second combobox"); cb2.Focus(); return; } if (cb3.SelectedIndex == -1) { MessageBox.Show("Nothing yet selected in the third combobox"); cb2.Focus(); return; } if (tb2.Text.Trim().Length == 0) { MessageBox.Show("Textbox can't be empty"); tb2.Focus(); return; } sql += String.Format("
{0} {1} {2} {3}", cb1.SelectedItem, cb2.SelectedItem, cb3.SelectedItem, tb2.Text); } } textBox1.Text = sql; } private void btnDeleteControls_Click(object sender, EventArgs e) { for (int i = this.Controls.Count - 1; i >= 0; i--) { object tag = this.Controls[i].Tag; if (tag != null && tag.ToString() == "dynamic") this.Controls.RemoveAt(i); } cLeft = 1; textBox1.Clear(); }

Vulpes · Answer

Glad I could help, Ken :)

Ken H · Answer

Your answer was wonderful, your answer helped me too much. thank for vulpes ken

Ken H · Answer

hi vulpes, thank for you,but there is a problem is not resolved,that is how to make the program remember the current dynamically generated controls and user selection or input values. for example, the user dynamically generate the N controls, then the next time you start the Form, also with N controls and the last entered value. I try to will current control the number and user input values ??are saved to the configuration file, but failed. thank for vulpes Ken

Anubhav Chaudhary · Answer

First of all I want to know weather I can use Grid View Instead of Text Box to display the data of SQL?????

How to extract the value of dynamically generated controls?

Answers (6)