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Windows Forms FAQ resources

4. Windows Forms Data Binding

4.7 How can I bind an ArrayList to a DataGrid?


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 value and the other named sqrt. 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. Below are some code snippets. You can download a working project that also has code to delete rows and add new rows to the bound arraylist.

private void Form1_Load(object sender, System.EventArgs e)
          {
               CreateArrayList();
               BindArrayListToGrid();
          }

          private void BindArrayListToGrid()
          {
               dataGrid1.DataSource = arrayList1;

               //create a custom tablestyle and add two columnstyles
               DataGridTableStyle ts = new DataGridTableStyle();
               ts.MappingName = "ArrayList";

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

               //create a column for the value property
               DataGridTextBoxColumn cs = new DataGridTextBoxColumn();
               cs.MappingName = "value"; //public property name
               cs.HeaderText = "Random Number";
               cs.Format = "f4";
               cs.Width = colwidth;
               ts.GridColumnStyles.Add(cs);

               //create a column for the sqrt property
               cs = new DataGridTextBoxColumn();
               cs.MappingName = "sqrt"; //public property name
               cs.HeaderText = "Square Root";
               cs.Format = "f4";
               cs.Width = colwidth;
               ts.GridColumnStyles.Add(cs);

               dataGrid1.TableStyles.Clear();
               dataGrid1.TableStyles.Add(ts);
          }

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

               //add some items
               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 struct RandomNumber
          {
               private double number;

               public RandomNumber(double d)
               {
                    number = d;
               }

               public double value
               {
                    get{ return number; }
                    set{ number = value;}
               }

               public double sqrt
               {
                    get {return Math.Sqrt(this.value);}
               }
          }