I am using a DataGrid to show the contents of an underlying DataTable,
generated at runtime (not bound to a database table or anything).

Everything works well when binding the DataColumn's of my table to
simple types, but I have problems binding a column to a custom class,
MyClass (see code below). The values of this column displays nicely (due
to th ToString method), but I am not able to modify the contents of the
column. All other columns are editable, and the underlying value of
objects in each cell are changed when I edit the cell value.

How do I make columns bound to custom classes editable???

Any help will be appreciated,

Ole Storm.


Code sample:

(...)
// Initializing the DataTable
DataTable dt = new DataTable("Table1");
dt.Columns.Add("First_Col", typeof(string));
dt.Columns.Add("Second_Col", typeof(int));
dt.Columns.Add("Thrid", typeof(double));
dt.Columns.Add("Fourth", typeof(System.DateTime));
DataColumn col = new DataColumn("Fifth", typeof(MyClass));
col.ReadOnly = false;
dt.Columns.Add(col);

Object[] obs = new Object[5]{"test", 2, 3.14, new DateTime(1969,5,5),
new MyClass("one")};
dt.Rows.Add(obs);
obs = new Object[5]{"abcdef", 17, 3.14*2.71, new DateTime(1967,6,26),
new MyClass("two")};
dt.Rows.Add(obs);
obs = new Object[5]{"defg", 37, 3.14*2.71, new DateTime(1967,6,26), new
MyClass("aaaabbb")};
dt.Rows.Add(obs);
DataView dv = new DataView(dt);
dv.AllowNew = false;
dv.AllowDelete = false;
dataGrid1.SetDataBinding(dv, "");
(...)

public struct MyClass : IComparable
{
private string s;
public MyClass(string a)
{
s=a+a;
}
public string Val
{
get
{
return s;
}
set
{
s=value;
}
}

public override string ToString()
{
return s;
}
#region IComparable Members

public int CompareTo(object obj)
{
if(obj is MyClass)
{
return this.s.Length.CompareTo(((MyClass)obj).s.Length);
}
else
throw new Exception("Incompatible objects");
return 0;
}

#endregion

[quoted text, click to view]

With the help of a colleague I was able to solve this one my self. I
hope someone will find the solution helpful.

The solution was to extend the class TypeConverter, and tie the
typeconverter to my custom class by using a typeconverter attribute.

The typeconverter for my custom class looks like this:

public class MyConverter : TypeConverter
{
public override bool CanConvertFrom(ITypeDescriptorContext context,
Type sourceType)
{
if(sourceType.Equals(typeof(string)))
return true;
else
return false;
}

public override object ConvertFrom(ITypeDescriptorContext context,
System.Globalization.CultureInfo culture, object value)
{
try
{
return new MyClass((string)value);
}
catch(Exception e)
{
return base.ConvertFrom (context, culture, value);
}
}
}


- and is tied to my cuustom class MyClass like this:

[TypeConverter(typeof(MyConverter))]
public struct MyClass : IComparable
{
private string s;
(...)
}

In this way the DataGrid column representing instances of MyClass became
editable like the other columns!

Regards,

Ole Storm.

[quoted text, click to view]