WinForms: Binding a ComboBox to a List of Custom Objects with DisplayMember and ValueMember
I've looked through the documentation and I'm still confused about I've been researching this but I've been banging my head against this for hours. I'm dealing with I'm optimizing some code but I've encountered a strange issue with I'm working on a personal project and I'm trying to bind a `ComboBox` in my WinForms application to a list of custom objects, but I'm running into issues with the `DisplayMember` and `ValueMember` properties not functioning as expected... I've created a simple class called `Product` with properties `Id` and `Name`: ```csharp public class Product { public int Id { get; set; } public string Name { get; set; } } ``` I then create a list of `Product` instances and set it as the `DataSource` of my `ComboBox` like this: ```csharp List<Product> products = new List<Product> { new Product { Id = 1, Name = "Product A" }, new Product { Id = 2, Name = "Product B" }, new Product { Id = 3, Name = "Product C" } }; comboBoxProducts.DataSource = products; comboBoxProducts.DisplayMember = "Name"; comboBoxProducts.ValueMember = "Id"; ``` When I run the application, the `ComboBox` displays the names correctly, but when I try to retrieve the selected value using `comboBoxProducts.SelectedValue`, I get a `NullReferenceException`. I've checked that the `DataSource` is set before I try to access the selected value. Here's what I have tried so far: - I ensured that the `ComboBox` is not null and that I am accessing `SelectedValue` after the `ComboBox` has been populated. - I placed breakpoints to check if the `DataSource` is being set correctly and confirmed the list has items. - I've also tried calling `comboBoxProducts.Refresh()` after setting the `DataSource`, but it didn't help. Interestingly, if I hard-code a value for `comboBoxProducts.SelectedValue` in the form's constructor, it works without any issues. What could be causing this issue, and how can I properly get the selected value from the `ComboBox` after binding it to the list of custom objects? I'm working on a API that needs to handle this. Has anyone dealt with something similar? Is this even possible? I'm working with C# in a Docker container on macOS. Is there a simpler solution I'm overlooking? I'm working in a Ubuntu 22.04 environment. Any advice would be much appreciated. I'd really appreciate any guidance on this.