Question

So, I have a DataGridView using as datasource a BindingList

DataGridView.DataSource = new  BindingList<Car>{...} 

Where

public class Car {     public ColorName Color { get; set;} } 

with

public class ColorName {     public int Id {get; set;}     public string Name{get; set;} } 

and I use a Combobox column:

DataGridViewComboBoxColumn colorNameDataGridViewTextBoxColumn; colorNameDataGridViewTextBoxColumn.DataPropertyName = 'Color'; colorNameDataGridViewTextBoxColumn.HeaderText = 'Color'; colorNameDataGridViewTextBoxColumn.Name = 'Color'; colorNameDataGridViewTextBoxColumn.DisplayMember = 'Name'; colorNameDataGridViewTextBoxColumn.ValueMember = 'Id'; colorNameDataGridViewTextBoxColumn.DataSource = new ColorName[] {...}; 

How can I get this to work ?! Now I get an exception because I think it tries to cast the Id to ColorName.

I tried with an empty ValueMember or adding a direct cast operator to ColorName class but can’t get it to work.

Sure I can use an int in the Car class to represent the color but is not as nice.

As you probably guessed those classes are in fact Castle Project ActiveRecord-s.

Any ideas are welcome !

Answer 1

Did you try ValueMember = ” or ValueMember = ‘.’?

Really hacky, but you could add a property on ColorName that is itself? (perhaps via a partial class)

public ColorName Self {get {return this;}} 

then set `ValueMember = ‘Self’;’

Other than that, you’d probably need a TypeConverter

The other option might be to override ToString() on ColorName to return Name, and not have a value/display member?

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(update: no it doesn’t)

Have checked, and ToString() seems to work :

public override string ToString() { return Name; } 

and just don’t set a DisplayMember or a ValueMember.

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Well whad’ya know – the ‘Self’ trick works too …

using System; using System.ComponentModel; using System.Windows.Forms; class ColorName {     public ColorName(int id, string name) {         this.Id = id;         this.Name = name;     }     public int Id { get; private set; }     public string Name { get; private set; }      // maybe declare this one in a partial class...     public ColorName Self { get { return this; } } } class Car {     public ColorName Color { get; set; } }  static class Program {     [STAThread]     static void Main()     {         Application.EnableVisualStyles();         using(Form form = new Form())         using (DataGridView grid = new DataGridView())         {             grid.Dock = DockStyle.Fill;             grid.AutoGenerateColumns = false;             ColorName[] colors = new[] {               new ColorName(1,'Red'),               new ColorName(2,'Blue'),               new ColorName(3,'Green')             };             var col = new DataGridViewComboBoxColumn             {                 DataPropertyName = 'Color',                 HeaderText = 'Color',                 Name = 'Color',                 DisplayMember = 'Name',                 ValueMember = 'Self',                 DataSource = colors             };              grid.Columns.Add(col);             grid.DataSource = new BindingList<Car> {                 new Car { Color = colors[0]}             };             form.Controls.Add(grid);             Application.Run(form);         }     } }