Send values from one form to another form

I want to pass values between two Forms (c#). How can I do it?

I have two forms: Form1 and Form2.

Form1 contains one button. When I click on that button, Form2 should open and Form1 should be in inactive mode (i.e not selectable).

Form2 contains one text box and one submit button. When I type any message in Form2's text box and click the submit button, the Form2 should close and Form1 should highlight with the submitted value.

How can i do it? Can somebody help me to do this with a simple example.

There are several solutions to this but this is the pattern I tend to use.

// Form 1
// inside the button click event
using(Form2 form2 = new Form2()) 
{
    if(form2.ShowDialog() == DialogResult.OK) 
    {
        someControlOnForm1.Text = form2.TheValue;
    }
}

And...

// Inside Form2
// Create a public property to serve the value
public string TheValue 
{
    get { return someTextBoxOnForm2.Text; }
}

private void button1_Click(object sender, EventArgs e)
{
        Form2 frm2 = new Form2(textBox1.Text);
        frm2.Show();    
}

---

 public Form2(string qs)
    {
        InitializeComponent();
        textBox1.Text = qs;
        
    }

Define a property

public static class ControlID {  
    public static string TextData { get; set; }
}

In the form2

private void button1_Click(object sender, EventArgs e)
{  
    ControlID.TextData = txtTextData.Text;   
}

Getting the data in form1 and form3

private void button1_Click(object sender, EventArgs e)
{   
    string text=  ControlID.TextData;   
}

After a series of struggle for passing the data from one form to another i finally found a stable answer. It works like charm.

All you need to do is declare a variable as public static datatype 'variableName' in one form and assign the value to this variable which you want to pass to another form and call this variable in another form using directly the form name (Don't create object of this form as static variables can be accessed directly) and access this variable value.

Example of such is,

Form1

public static int quantity;
quantity=TextBox1.text; \\Value which you want to pass

Form2

TextBox2.Text=Form1.quantity;\\ Data will be placed in TextBox2

Declare a public string in form1

public string getdata;

In button of form1

form2 frm= new form2();
this.hide();
form2.show();

To send data to form1 you can try any event and code following in that event

form1 frm= new form1();
form1.getdata="some string to be sent to form1";

Now after closing of form2 and opening of form1, you can use returned data in getdata string.

I've worked on various winform projects and as the applications gets more complex (more dialogs and interactions between them) then i've started to use some eventing system to help me out, because management of opening and closing windows manually will be hard to maintain and develope further.

I've used CAB for my applications, it has an eventing system but it might be an overkill in your case :) You could write your own events for simpler applications

declare string in form1 public string TextBoxString;

in form1 click event add

private void button1_Click(object sender, EventArgs e)
    {
        Form1 newform = new Form1();
        newform = this;
        this.Hide();
        MySecform = new Form2(ref newform);
        MySecform.Show();
    }

in form2 constructer

public Form2(ref Form1 form1handel)
    {
        firstformRef = form1handel;
        InitializeComponent();
    }

in form2 crate variable Form1 firstformRef;

private void Submitt_Click(object sender, EventArgs e)
    {
        firstformRef.TextBoxString = textBox1.Text;
        this.Close();
        firstformRef.Show();

    }

Form1 Code :

private void button1_Click(object sender, EventArgs e)
{
            Form2 f2 = new Form2();
            f2.ShowDialog();
            MessageBox.Show("Form1 Message :"+Form2.t.Text); //can put label also in form 1 to show the value got from form2
}

Form2 Code :

        public Form2()
        {
            InitializeComponent();
            t = textBox1;                        //Initialize with static textbox
        }
        public static TextBox t=new TextBox();   //make static to get the same value as inserted
        private void button1_Click(object sender, EventArgs e)
        {
            
            this.Close();
            
        }

It Works!

In this code, you pass a text to Form2. Form2 shows that text in textBox1. User types new text into textBox1 and presses the submit button. Form1 grabs that text and shows it in a textbox on Form1.

public class Form2 : Form
{
    private string oldText;
    
    public Form2(string newText):this()
    {
        oldText = newText;
        btnSubmit.DialogResult = DialogResult.OK;
    }

    private void Form2_Load(object sender, EventArgs e)
    {
        textBox1.Text = oldText;
    }

    public string getText()
    {
        return textBox1.Text;
    }

    private void textBox1_KeyUp(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.Enter)
        {
            DialogResult = System.Windows.Forms.DialogResult.OK;
        }
    }
}

And this is Form1 code:

public class Form1:Form
{
    using (Form2 dialogForm = new Form2("old text to show in Form2"))
    {
        DialogResult dr = dialogForm.ShowDialog(this);
        if (dr == DialogResult.OK)
        {
            tbSubmittedText = dialogForm.getText();
        }
        dialogForm.Close();
    }
}

Ok so Form1 has a textbox, first of all you have to set this Form1 textbox to public in textbox property.

Code Form1:

Public button1_click()
{
    Form2 secondForm = new Form2(this);
    secondForm.Show();
}

Pass Form1 as this in the constructor.

Code Form2:

Private Form1 _firstForm;

Public Form2(Form1 firstForm)
{
    _firstForm = firstForm:
}

Public button_click()
{
    _firstForm.textBox.text=label1.text;
    This.Close();
}

you can pass as parameter the textbox of the Form1, like this:

On Form 1 buttom handler:

private void button2_Click(object sender, EventArgs e)
{
Form2 newWindow = new Form2(textBoxForReturnValue);
newWindow.Show(); 
}

On the Form 2

public static TextBox textBox2; // class atribute

public Form2(TextBox textBoxForReturnValue)
{
    textBox2= textBoxForReturnValue;
}

private void btnClose_Click(object sender, EventArgs e)
{

    textBox2.Text = dataGridView1.CurrentCell.Value.ToString().Trim();
    this.Close();
}

Constructors are the best ways to pass data between forms or Gui Objects you can do this. In the form1 click button you should have:

Form1.Enable = false;
Form2 f = new Form2();
f.ShowDialog();

In form 2, when the user clicks the button it should have a code like this or similar:

this.Close();
Form1 form = new Form1(textBox1.Text)
form.Show();

Once inside the form load of form 1 you can add code to do anything as you get the values from constructor.

How to pass the values from form to another form

1.) Goto Form2 then Double click it. At the code type this.

public Form2(string v)
{
  InitializeComponent();
  textBox1.Text = v;
}

2.) Goto Form1 then Double click it. At the code type this. //At your command button in Form1

private void button1_Click(object sender, EventArgs e)
{
   Form2 F2 = new Form2(textBox1.Text);
   F2.Show();
}

This is very simple. suppose you have 2 window form Form1 and Form2 and you want to send record of textbox1 from Form1 to Form2 and display this record in label1 of Form2; then in Form2 create a label which name is label1 and go to the property of label1 and set 'Modifiers'=public and in Form one create a textBox with id textBox1 and a button of name submit then write the following code on button click event

button1_Click(object sender, EventArgs e)
{
  Form2 obj=new Form2();
  obj.label1.text=textBox1.text.ToString();
  obj.show();
}

thats it... for this way you can bind dataset record to another form's datagridview......

You can make use of a different approach if you like.

1. Using System.Action (Here you simply pass the main forms function as the parameter to the child form like a callback function)
2. OpenForms Method ( You directly call one of your open forms)

Using System.Action

You can think of it as a callback function passed to the child form.

// -------- IN THE MAIN FORM --------

// CALLING THE CHILD FORM IN YOUR CODE LOOKS LIKE THIS
Options frmOptions = new Options(UpdateSettings);
frmOptions.Show();
 
// YOUR FUNCTION IN THE MAIN FORM TO BE EXECUTED
public void UpdateSettings(string data)
{
   // DO YOUR STUFF HERE
}

// -------- IN THE CHILD FORM --------

Action<string> UpdateSettings = null;

// IN THE CHILD FORMS CONSTRUCTOR
public Options(Action<string> UpdateSettings)
{
    InitializeComponent();
    this.UpdateSettings = UpdateSettings;
}

private void btnUpdate_Click(object sender, EventArgs e)
{
    // CALLING THE CALLBACK FUNCTION
    if (UpdateSettings != null)
        UpdateSettings("some data");
}

OpenForms Method

This method is easy (2 lines). But only works with forms that are open. All you need to do is add these two lines where ever you want to pass some data.

Main frmMain = (Main)Application.OpenForms["Main"];
frmMain.UpdateSettings("Some data");

I provided my answer to a similar question here

You can use this;

Form1 button1 click

private void button1_Click(object sender, EventArgs e)
{
    Form2 frm2 = new Form2();
    this.Hide();
    frm2.Show();
}

And add this to Form2

public string info = "";

Form2 button1 click

private void button1_Click(object sender, EventArgs e)
{
        
    info = textBox1.Text;
    this.Hide();
    BeginInvoke(new MethodInvoker(() =>
    {
        Gogo();
    }));
}

public void Gogo()
{
    Form1 frm = new Form1();
    frm.Show();
    frm.Text = info;
}

if you change Modifiers Property of a control in a Form to Public, another Forms can access to that control. f.e. :

    Form2 frm;
    private void Form1_Load(object sender, EventArgs e)
    {
        frm = new Form2();
        frm.Show();
    }
    private void button1_Click(object sender, EventArgs e)
    {
        MessageBox.Show(frm.txtUserName.Text); 
        //txtUserName is a TextBox with Modifiers=Public        
    }

// In form 1
public static string Username = Me;

// In form 2's load block
string _UserName = Form1.Username;

the tag Properties receive object value ( C# send value to another form )

private void btn_Send_Click(object sender, EventArgs e)
{
    Form frm = new formToSend();
    frm.tag = obj;
    frm.ShowDialog();
}

Receive value that sent from previous form ( frm )
Ex: sent data is string ( we need to type casting first, because tag value is an object )

public Receive_Form()
{
    InitializeComponent();
    MessageBox.Show((string)this.Tag);
}

How about using a public Event

I would do it like this.

public class Form2
{
   public event Action<string> SomethingCompleted;

   private void Submit_Click(object sender, EventArgs e)
   {
       SomethingCompleted?.Invoke(txtData.Text);
       this.Close();
   }
}

and call it from Form1 like this.

private void btnOpenForm2_Click(object sender, EventArgs e)
{
    using (var frm = new Form2())
    {
        frm.SomethingCompleted += text => {
            this.txtData.Text = text;
        };

        frm.ShowDialog();
    }
}

Then, Form1 could get a text from Form2 when Form2 is closed

Thank you.