January 21, 2004 .net

Setting DataGrid Styles for Custom Types

I was data binding an ArrayList of objects of a custom type, e.g. class Person { public string Name; public DateTime BirthDate; public int Teeth; }, to a DataGrid today and everything working great til I wanted to filter one of the columns out (who cares how many Teeth a person has?). I was all set with table styles and grid styles like so:

void Form1_Load(object sender, EventArgs e) {
DataGridTableStyle tableStyle = new DataGridTableStyle();
tableStyle.DataGrid = this.dataGrid1;
tableStyle.MappingName = "Something???";
  string[] columns = { "Name", "BirthDate" }; // Skip Teeth
foreach( string column in columns ) {
DataGridTextBoxColumn columnStyle = new DataGridTextBoxColumn();
columnStyle.HeaderText = column;
columnStyle.MappingName = column;
  // Create ArrayList of Person objects...
  this.dataGrid1.DataSource = personList;

The problem was the table style’s MappingName. When DataBinding to a DataTable, it’s just the table name, but what is it when I’ve got a collection of objects of a custom type? Daniel Herling, a Software Design Engineer at Microsoft and the man” of the DataGrid, came to my rescue:

If you bind to an ITypedList (say, System.Data.DataTable) then the mapping name should be ITypedList::GetListName(). For a System.Data.DataTable this would be the name of the data table.

If you don’t bind to an IList that is not ITypedList then the mapping name should be list.GetType().Name where list is the list the data grid is bound to.

So, all I had to do was set the table style mapping name to the type of my custom class:

  tableStyle.MappingName = typeof(ArrayList).Name;

This wasn’t bad at all to bind a DataGrid to exactly the properties of my Person objects that I want w/o having to hack another custom shim type or changing the Person type itself to accommodate the data binding. Thanks, Daniel!