How to use bindingList and BindingSource at multiple places

Question

Hi ,

I have a BindingList and a BindingSource defined in a separate class . besides that i also have a custom datagridview , a datagridview on a form named form 1 , and two textbox on the form named form 2 . one of these textbox is used to add values to the BindingList and the other Textbox is used to update .

I am facing two problems and request expertise

1. Although i have coded but I am looking for a Best way by which this same Binding list is available to all three forms . so that whenever any form update a item or add a item in BindingList , it should reflect in all the forms .
2. I don't know how to code the Binding logics for both the update and add buttons in form2 .

DataRepository.cs

  namespace Rajr
{
    public static class DataRepository
    {
        private static BindingList<Item> dataList;
        public static BindingList<Item> DataList
        {
            get { return dataList; }
            set
            {
                if (dataList != null)
                    dataList.ListChanged -= DataList_ListChanged;

                dataList = value;

                if (dataList != null)
                    dataList.ListChanged += DataList_ListChanged;
            }
        }

        public static BindingSource DataSource { get; set; }

        static DataRepository()
        {
            DataList = new BindingList<Item>();
            DataSource = new BindingSource(DataList, null);
        }

        private static void DataList_ListChanged(object sender, ListChangedEventArgs e)
        {
            DataSource.ResetBindings(false);
        }
    }

    public class Item : INotifyPropertyChanged
    {
        private string itemName;
        public string ItemName
        {
            get { return itemName; }
            set
            {
                if (itemName != value)
                {
                    itemName = value;
                    OnPropertyChanged();
                }
            }
        }

        private int quantity;
        public int Quantity
        {
            get { return quantity; }
            set
            {
                if (quantity != value)
                {
                    quantity = value;
                    OnPropertyChanged();
                }
            }
        }

        private string measuringUnits;
        public string MeasuringUnits
        {
            get { return measuringUnits; }
            set
            {
                if (measuringUnits != value)
                {
                    measuringUnits = value;
                    OnPropertyChanged();
                }
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        }
    }

}

CustomDatagridview.cs

  public partial class CustomDatagridview : DataGridView
    {
        private bool inGotoNextControl = false;
        public CustomDatagridview()
        {
            this.AllowUserToAddRows = false;
            this.ColumnHeadersVisible = false;
            this.RowHeadersVisible = false;
            InitializeComponent();
            DataSource = DataRepository.DataSource;

        }

Form1.cs

 public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            // add some data 
            DataRepository.DataList.Add(new Item { ItemName = "Cookies", Quantity = 10, MeasuringUnits = "Pcs" });
            DataRepository.DataList.Add(new Item { ItemName = "Bread", Quantity = 5, MeasuringUnits = "Box" });
            DataRepository.DataList.Add(new Item { ItemName = "Candy", Quantity = 2, MeasuringUnits = "Pcs" });
            dataGridView1.DataSource = DataRepository.DataSource;
        }  

        private void Form1_Load(object sender, EventArgs e)
        {
           
        }
    }

form2.cs

It has three textboxes each for updating and adding items in ItemName , Quantity and MeasuringUnits .

public partial class Form2 : Form
{
   

    public Form2()
    {
        InitializeComponent();

        
    }

    private void Add_Click(object sender, EventArgs e)
    {
        // Add in  the BindingList
       
    }


}

Answer 1

Add BindingSource in DataRepository to DataBindings of TextBox in Form2 .

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
        // add some data 
        DataRepository.DataList.Add(new Item { ItemName = "Cookies", Quantity = 10, MeasuringUnits = "Pcs" });
        DataRepository.DataList.Add(new Item { ItemName = "Bread", Quantity = 5, MeasuringUnits = "Box" });
        DataRepository.DataList.Add(new Item { ItemName = "Candy", Quantity = 2, MeasuringUnits = "Pcs" });
        dataGridView1.DataSource = DataRepository.DataSource;
    }

    private void button1_Click(object sender, EventArgs e)
    {
        if (Application.OpenForms.OfType<Form2>().FirstOrDefault() != null)
        {
            return;
        }

        var frm2 = new Form2();
        frm2.StartPosition = FormStartPosition.CenterParent;
        frm2.Show(this);
    }
}

public partial class Form2 : Form
{
    private TextBox txbItemName;
    private TextBox txbQuantity;
    private TextBox txbMeasuringUnits;
    private Button btnAdd;

    public Form2()
    {
        //InitializeComponent();

        txbItemName = new TextBox();
        txbQuantity = new TextBox();
        txbMeasuringUnits = new TextBox();
        btnAdd = new Button() { Text = "Add New Item" };

        txbItemName.DataBindings.Add(new Binding(nameof(TextBox.Text), DataRepository.DataSource, nameof(Item.ItemName)));
        txbQuantity.DataBindings.Add(new Binding(nameof(TextBox.Text), DataRepository.DataSource, nameof(Item.Quantity)));
        txbMeasuringUnits.DataBindings.Add(new Binding(nameof(TextBox.Text), DataRepository.DataSource, nameof(Item.MeasuringUnits)));

        this.Controls.Add(txbItemName);
        this.Controls.Add(txbQuantity);
        this.Controls.Add(txbMeasuringUnits);
        this.Controls.Add(btnAdd);

        for (int i = 1; i < this.Controls.Count; i++)
        {
            this.Controls[i].Top = this.Controls[i - 1].Bottom + 5;
        }

        btnAdd.Click += Add_Click;
    }

    private void Add_Click(object sender, EventArgs e)
    {

        DataRepository.DataSource.Add(new Item());
        //DataRepository.DataSource.Add(new Item() { ItemName = "Empty", Quantity = 0, MeasuringUnits = "Pcs" });

        DataRepository.DataSource.MoveLast();
    }
}

Answer 2

Consider a singleton to share data. The following works but can be optimized, I did just enough to show sharing data between forms.

See the full source code here.

public sealed class DataSource
{
    private static readonly Lazy<DataSource> Lazy = 
        new(() => new DataSource());

    public static DataSource Instance => Lazy.Value;

    public readonly BindingSource BindingSource = new();
    public BindingList<Book> BindingList = new();

    private DataSource()
    {
        BindingList = new BindingList<Book>(DataOperations.Books());
        BindingSource.DataSource = BindingList;
    }
}

To set to the main form.

private void OnShown(object sender, EventArgs e)
{
    _bindingList = DataSource.Instance.BindingList;
    _bindingSource.DataSource = _bindingList;
    dataGridView1.DataSource = _bindingSource;
}

In a child form

public partial class EditForm : Form
{
    private readonly int _position;

    public EditForm()
    {
        InitializeComponent();
        Shown += EditFormShown;
    }

    public EditForm(int position)
    {
        InitializeComponent();
        Shown += EditFormShown;
        _position = position;
    }

    private void EditFormShown(object sender, EventArgs e)
    {
        TitleTextBox.DataBindings.Add(
            "Text",
            DataSource.Instance.BindingList[_position],
            "Title");

        PriceTextBox.DataBindings.Add(
            "Text",
            DataSource.Instance.BindingList[_position],
            "Price");
    }

    private void SaveButton_Click(object sender, EventArgs e)
    {
        DataSource.Instance.BindingSource.ResetCurrentItem();
        DialogResult = DialogResult.OK;
    }
}