I was running into a problem with the DataGridView while binding it to an
object Collection.  I got it working and I thought others might like to know
how.

-------------- Problem -------------
The grid was bound to a simple object collection.  The object contained
string and decimal properties, nothing to fancy.  When an item was added to
the collection I would databind as follows (this happened on each item
"Add"):

myObject.CollectionProperty.Add(myBasicObject);

dgvGrid.DataSource = myObject.CollectionProperty;
bsBindingSource.DataSource = myObject.CollectionProperty;
dgvGrid.DataSource =  bsBindingSource;

The reason I was binding twice was that the first bind didn't appear to
allow the grid to hold more than one item.

Now at run time if I added an object using the method above the grid would
populate and it appeared to work fine.  If I enabled deleting on the grid I
could even delete the objects (using the grid and the delete button on my
keyboard)... But wait!  If I added an item after I deleted all the items in
the grid (collection) and try to select it the grid would bomb out with the
following error: "Index -1 does not have a value".

-------------- Solution -----------------
After searching endlessly for some info I found that a few folks (thomas &
Pieter)  had run into this error but could not find any answer as to why.  I
decided to examine related objects (looking for cool property or a method
that might save the day) and while doing so I came across the
ResetBindings(bool) method of the BindingSource.

I moved the binding information in the Add routine to a more appropriate
location in the form initialization  Then I simply added

bsBindingSource.ResetBindings(false);

to the Add routine, just after the object is added to the collection.
Viola!  Problem was fixed, and I no longer needed to bind the grid twice.  I
was able to make the binding work now with just this:

bsBindingSource.DataSource = myObject.CollectionProperty;
dgvGrid.DataSource =  bsBindingSource;

Any event that's probably just a problem I would have cause I'm just
amateur, but who knows, maybe it might help someone.

Thanks,

Matt

references:
http://www.dotnetnewsgroup.com/message/329608.aspx

http://www.eggheadcafe.com/forumarchives/netframeworknetwindowsforms/jul2005/pos
t23270599.asp

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