I'm building a fairly complex application and it's been awhile since I've built any desktop apps. Here's the issue I'm currently facing. I have a number of objects I've modeled and interfaces which need to manage the associations. The problem is that form controls don't allow a key to be associated with a particular line and I'm wondering how you all manage that.

For example, let's say that I was collecting information on computer suppliers. For each of the computers I have I may have a number of vendors with their own details. The way I have the form setup is to have a ListBox with all the computers listed and when you click on the computer name, it shows the current list of vendors, allowing you to add them as well. Each computer is assigned a unique identifier, but there's no direct way of associating the unique identifier with the row in the ListBox so that I can then cross-reference the vendors by the computer id.

How do you all work around such a problem?

Oh, I should add that sometimes a sortable control is used (where the user can click and sort in the interface, not manually sorted via code) and I'd need to maintain any associations.

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Jeremy Miller
Content Farmer - Optimized Automated Blog Posting

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Found the answer, so I thought I'd share it, briefly:

1) Create an object for the item you want to list in the listbox. Allow this object to contain the primary key as well as a ToString() function. The ToString() function should return the text to be displayed in the listbox.

2) Create an array of instances of the object from #1.

3) Set the datasource of the listbox to the array created in #2.

4) Add/Delete/Modify the array from #2 by calling the primary key of the selected object (which will be of the object type and not a string as normal).

5) Set the listbox datasource to null.

6) Set the listbox datasource to the array from #2.

Steps 5 and 6 are necessary because array's don't update the listbox that they have changed (there's some event missing there, but I don't recall what it's called), but changing the source to null and then back to the datasource triggers a full update. Skipping step 6 doesn't cue the language into the fact that the source has changed.

Hope this helps someone else!

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Jeremy Miller
Content Farmer - Optimized Automated Blog Posting

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