[RESOLVED] Bind List to combobox

[MrNorth]

Hi!

I am working on a new winforms application that is receiving data from a WCF service. The programmer has implemented the services like this:

Note that this sample is C# but I will be working in VB.NET

[OperationContract]
        [FaultContract(typeof(ServiceFault))]
        [FaultContract(typeof(ValidationFault))]
        [WsdlDoc("Search all cars")]
        [return: MessageParameter(Name = "Cars")]
        List<Car> FindCars(List<SearchCriteriaItem> criterias);

There seems to be a limitation in the combobox so that it can only bind to name/value collections?

I use the

- datasource
- valuemember
- displaymember

properties of the combobox.

I am pretty new to winforms, I have a background in asp.net

kind regards
Henrik

[chris128]

I'm fairly sure you can bind it to whatever you want as long as you give it a valid displaymember property (although I'm a little too used to WPF now to be 100% sure about winforms).
Can you post the code you are using to do the binding and tell us what is happening (do you get any errors etc) ?

[jmcilhinney]

That developer needs to brush up on his English for a start. "criterion" is the singular and "criteria" is the plural.

As for the question, the ComboBox can bind to any IList or IListSource object. The generic List class implements the generic IList interface so no problem. You simply assign the name of the property whose data you want displayed to the DisplayMember, e.g.

myComboBox.DisplayMember = "Name"
myComboBox.ValueMember = "ID"
myComboBox.DataSource = myList

In actual fact, the DisplayMember and ValueMember accept the names of PropertyDescriptors. PropertyDescriptors are inherently created for properties but a class can create custom PropertyDescriptors, which is why DataColumn names can be used for bound DataTables.

[MrNorth]

Thanks, that worked! I have no idea what I did wrong before.

I have another question I stumbled across recently.

If I bind a List<of Car> to a GridView, how can I then get the selected row and cast that to an object of type Car? I tried this:

dim c as Car = ctype(myCarsGV.SelectedRows(0).DataBoundItem).Row, Car)

but get a casting error. The nature of this question is a result to my poor winforms skills. This is no problem in ASP.NET...

/Henrik

[chris128]

Try DirectCast instead of CType (i'll be honest with you here, thats just a total stab in the dark)

[jmcilhinney]

Um, if the DataSource is a List(Of Car) then the DataBoundItem is a Car, so why are you trying to get the Row property? If you bind a Datatable then the DataBoundItem is a DataRowView, so you can get a DataRow from its Row property, but you want a Car, which you already have and which has no Row property. It's just:

Dim c As Car = DirectCast(myCarsGV.SelectedRows(0).DataBoundItem, Car)