I am just wondering how best to handle a list of value types that are displayed in a data list. For example, I have an entity called Document, Document has a set of Links. Links are a value type and mapped as collection of composite elements.

I display the list of links in a data grid. I want the ability to edit a a Link if the url has changed. So how do I handle the editing of a value type if it doesnt have an identity. Generally, Value types are immutable and that is ok. I would just create a new Link object and Delete the old, but Im still not sure how to find the Link to delete in the list after a postback. Usually, with a Datagrid displaying entities, you can use the entity id as the key. Having a key makes it easy to find the item. I guess Im just confused about how to get the value type if it has no key.

Thanks for any help.

So, as I understand, the main problem is to find item in grid. In this case you can use CommandName and CommandArgument for grid command handling. For example you put "Delete" button into the grid with CommandName="delete" and CommandArgument="<%# bind your unique link attribute here %>". Now in your grid.ItemCommand eventhadler method (or grid.DeleteCommand) you can check eventargs (e.commandName and e.CommandArgument) for your options and here you can use serch by your CommandArgument value.

Note, than your CommandArgument can be composite, something like <DocumentId>_<LinkName>.

Ghen,
I think what you are trying to say is that I must have some kind of key. this key must be unique. For example the link name must be unique. Then I must search through the collection to find the value.

The only gotcha I guess is that the key must be unique. This cant always be guranteed with value types, but I guess there isnt really an alternative. I have to be able to identify the value somehow.