How to Bind an ArrayList to a DataGrid

How to Bind an ArrayList to a DataGrid

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Overview

Here is a technique for binding an arraylist of objects where the objects contain public property that can appear as columns in the datagrid. In this example, the object contains 2 public doubles, one named "RandomValue" and the other named "SqrtValue". To bind this arraylist to a datagrid, add a custom tablestyle that has a MappingName of "ArrayList", and then use the property names as the MappingName for each column.

Example

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

namespace Akadia.DataGridArrayList
{
    public class DataGridArrayList : System.Windows.Forms.Form
    {
        private System.Windows.Forms.DataGrid dataGrid1;
        private ArrayList arrayList1;
        private System.Windows.Forms.Button buttonAddNew;
        private System.Windows.Forms.Button buttonDeleteCurrent;
        private System.ComponentModel.Container components = null;

        public DataGridArrayList()
        {
            InitializeComponent();
        }

        ...
        ...

        [STAThread]
        static void Main()
        {
            Application.Run(new DataGridArrayList());
        }

        // Create and Bind ArrayList to the Datagrid when loading
        private void DataGridArrayList_Load(object sender, System.EventArgs e)
        {
            CreateArrayList();
            BindArrayListToGrid();
        }

        // Create a custom tablestyle and add two columnstyles
        private void BindArrayListToGrid()
        {
            dataGrid1.DataSource = arrayList1;

            DataGridTableStyle ts = new DataGridTableStyle();
            ts.MappingName = "ArrayList";

            int colwidth = (dataGrid1.ClientSize.Width
                - ts.RowHeaderWidth
                - SystemInformation.VerticalScrollBarWidth - 5) / 2;

            // Create a column for the "RandomValue" property
            // defined in the RandomNumber Class
            DataGridTextBoxColumn cs = new DataGridTextBoxColumn();
            cs.MappingName = "RandomValue";  // Public property name
            cs.HeaderText = "Random Number";
            cs.Format = "f4";
            cs.Width = colwidth;
            ts.GridColumnStyles.Add(cs);

            // Create a column for the "SqrtValue" property
            // defined in the RandomNumber Class
            cs = new DataGridTextBoxColumn();
            cs.MappingName = "SqrtValue";  // Public property name
            cs.HeaderText = "Square Root";
            cs.Format = "f4";
            cs.Width = colwidth;
            ts.GridColumnStyles.Add(cs);

            // Add the custom tablestyle to the DataGrid
            dataGrid1.TableStyles.Clear();
            dataGrid1.TableStyles.Add(ts);
        }

        private void CreateArrayList()
        {
            arrayList1 = new ArrayList();

            // Add some random Numbers
            Random r = new Random();
            for (int i = 0; i < 20; ++i)
            {
                arrayList1.Add(new RandomNumber(r.NextDouble()));
            }

        }

        // Create a struct or class that defines what you want in each row
        // the different columns in the row must be public properties
        public class RandomNumber
        {
            private double num;

            // Constructor
            public RandomNumber(double d)
            {
                num = d;
            }

            // Public Property "RandomValue" used
            // as Column in the DataGrid
            public double RandomValue
            {
                get{ return num; }
                set{ num = value;}
            }

            // Public Property "SqrtValue" used
            // as Column in the DataGrid
            public double SqrtValue
            {
                get {return Math.Sqrt(this.num);}
            }
        }

        // Add a new random Number to the ArrayList and
        // then refresh the DataGrid
        private void buttonAddNew_Click(object sender, System.EventArgs e)
        {
            Random r = new Random();
            arrayList1.Add(new RandomNumber(r.NextDouble()));

            // Refresh the Datagrid with the new random number
            CurrencyManager cm =
              (CurrencyManager) this.dataGrid1.BindingContext[arrayList1];
            if (cm != null)
            {
                cm.Refresh();
            }

        }

        // Delete current Entry from the ArrayList.
        private void buttonDeleteCurrent_Click(object sender, System.EventArgs e)
        {
            // Get the current position due to not allow empty datagrid.
            CurrencyManager cm =
              (CurrencyManager) this.BindingContext[dataGrid1.DataSource];

            if (cm.Count <= 1)
            {
                return;  // Do not allow an empty DataGrid
            }

            // Place cursor on position up
            int removeAt = cm.Position;
            if (removeAt > 0)
            {
                cm.Position = removeAt - 1;
            }

            // Remove current Entry
            arrayList1.RemoveAt(removeAt);

            if (cm != null)
            {
                cm.Refresh();
            }
        }

        // Select the entire row when the user clicks on a cell in the row
        private void dataGrid1_MouseUp(object sender, System.Windows.Forms.MouseEventArgs e)
        {
            System.Drawing.Point pt = new Point(e.X, e.Y);
            DataGrid.HitTestInfo hti = dataGrid1.HitTest(pt);
            if (hti.Type == DataGrid.HitTestType.Cell)
            {
                dataGrid1.CurrentCell = new DataGridCell(hti.Row, hti.Column);
                dataGrid1.Select(hti.Row);
            }
        }
    }
}