将对象从一种窗口形式传递到另一种形式

Question

I have two windows forms in my application. First one is Main form and the second one is lookup form. I'm trying to open lookup form from the main form in a text box key leave event and then I'm opening the lookup form. My lookup form has a data grid view and I' loading it in the form load event of the lookup form. I'm reading my selected value on the grid view of the lookup window to an object. I want to close the lookup window as soon as I read the values of the selected row to the object and I want to pass it to the main form? How can I do that? This is what I have done. In the main form.

        LookupModelType="";
        if (e.KeyCode.Equals(Keys.F3))
        {
            foreach (Form frm in Application.OpenForms)
            {
                if (frm is FormControllers.Lookup)
                {
                    if (frm.WindowState == FormWindowState.Minimized)
                    {
                        frm.WindowState = FormWindowState.Normal;
                        frm.Focus();
                        return;
                    }
                }
            }
                LookupModelType = "Product";
                FormControllers.Lookup newLookUp = new FormControllers.Lookup(LookupModelType);                
                newLookUp.ShowDialog(this);
        }

In the lookup window

  private string GridType = "";
        public Lookup(String  LookupModelType)
        {
            InitializeComponent();
            this.GridType = LookupModelType; 
        }

        private void Lookup_Load(object sender, EventArgs e)
        {
            if (GridType == "Product")
            {
                using(DataControllers.RIT_Allocation_Entities RAEntity  = new DataControllers.RIT_Allocation_Entities())
                {
                    dgvLookup.DataSource = RAEntity.TBLM_PRODUCT.ToList<DataControllers.TBLM_PRODUCT>();
                }  
            }
            dgvLookup.ReadOnly = true;
        }

        private void dgvLookup_CellClick(object sender, DataGridViewCellEventArgs e)
        {
            if (e.RowIndex < 0)
            {
                return;
            }
            int index = e.RowIndex;
            dgvLookup.Rows[index].Selected = true;
        }

Answer 1

you can do it like blow :

in the Main form :

   private void textBox1_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.F3)
        {
            LookupForm look = new LookupForm();
            var result  = look.ShowDialog();

            if(result == DialogResult.OK)
            {
                MessageBox.Show(look.data.ToString());
            }
        }
    }

and in the look up form you have to declare 1 variable and fill whenever cell clicked

public partial class LookupForm : Form
{
    public object data = new object();
    private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
    {
        data = dataGridView1.Rows[e.RowIndex].Cells[e.ColumnIndex].Value;
        this.DialogResult = DialogResult.OK;
        this.Close();
    }
}

of course, for better performance, you can declare the variable in specific type

Answer 2

To share data between Parent Child forms using events, here are the things needed:

1. A public custom event args class to share data.
2. Child form to have a event.
3. In your parent form whenever you create an instance of child, you need to register eventhandlers

Please note that the code below is just a demo code and you will need to add null checks etc. to make it "robust".

Custom event args below

public class ValueSelectedEventArgs : EventArgs
{
    public object Value { get; set; }
}

Your lookup form should have the following event declared:

        public event EventHandler ValueSelected;

        protected virtual void OnValueSelected(ValueSelectedEventArgs e)
        {
            EventHandler handler = ValueSelected;
            if (handler != null)
            {
                handler(this, e);
            }

            // if you are using recent version of c# you can simplyfy the code to ValueSelected?.Invoke(this, e);     
        }

In my case I am firing the event on listbox selected index change and closing the form as well. Code for it:

        private void checkedListBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            var i = this.checkedListBox1.SelectedIndex;
            ValueSelectedEventArgs args = new ValueSelectedEventArgs();
            args.Value = i;
            OnValueSelected(args);
            this.Close();
        }

Finally in the parent form you have to register for the eventhandler

private void textBox1_Leave(object sender, EventArgs e)
{
    lookup myLookup = new lookup();
    myLookup.ValueSelected += MyLookup_ValueSelected;
    myLookup.Show();
}

    private void MyLookup_ValueSelected(object sender, EventArgs e)
    {
        textBox2.Text = (e as ValueSelectedEventArgs).Value.ToString();

    }

Answer 3

I personal like to add dynamically the lookup window, and I do something like this:

        //examble object
        class Person
        {
            public string FirstName { get; set; }
            public string LastName { get; set; }
        }
        // the value which you want to get from datagridview
        private Person _selectedValue;
        // the datagridview datasource, which you neet to set 
        private IEnumerable<Person> _gridDataSource = 
            new List<Person>()
                {
                    new Person {FirstName="Bob",LastName="Smith" },
                    new Person {FirstName="Joe",LastName="Doe"}
                };

        private void textBox1_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode== Keys.F3)
            {
                var btnOk = new Button() { Text = "Ok", Anchor= AnchorStyles.None };
                var btnCancel = new Button() { Text = "Cancel",Anchor= AnchorStyles.Right };

                var dg = new DataGridView();
                var bs = new BindingSource();
                bs.DataSource = _gridDataSource;
                dg.DataSource = bs;
                dg.Dock = DockStyle.Fill;
                dg.SelectionMode = DataGridViewSelectionMode.FullRowSelect;

                //setup a layout wich will nicely fit to the window
                var layout = new TableLayoutPanel();
                layout.Controls.Add(dg, 0, 0);
                layout.SetColumnSpan(dg, 2);
                layout.Controls.Add(btnCancel, 0, 1);
                layout.Controls.Add(btnOk, 1, 1);
                layout.RowStyles.Add(new RowStyle(SizeType.Percent));
                layout.RowStyles.Add(new RowStyle(SizeType.AutoSize));
                layout.ColumnStyles.Add(new ColumnStyle(SizeType.Percent));
                layout.ColumnStyles.Add(new ColumnStyle(SizeType.AutoSize));
                layout.Dock = DockStyle.Fill;

                //create a new window and add the cotnrols
                var window = new Form();
                window.StartPosition = FormStartPosition.CenterScreen;
                window.Controls.Add(layout);


                // set the ok and cancel buttons of the window
                window.AcceptButton = btnOk;
                window.CancelButton = btnCancel;
                btnOk.Click += (s, ev) => { window.DialogResult = DialogResult.OK; };
                btnCancel.Click += (s, ev) => { window.DialogResult = DialogResult.Cancel; };

                //here we show the window as a dialog
                if (window.ShowDialog() == DialogResult.OK)
                {
                        _selectedValue =(Person) bs.Current;
                        MessageBox.Show(_selectedValue.FirstName);
                }
            }
}