Display member in Combobox without losing reference to associated data - vb.net

Question

I have a TableAdapter for a table like:
ID_BRAND NAME_BRAND ... (Other columns)
(...) (...) (...)
I have a ComboBox where I need to add all NAME_BRANDs, but without losing the reference to their ID_BRAND, because there are some NAME_BRANDs identical, but with different ID_BRAND. Thhen when the user selects a name in the ComboBox, the correspondent ID_BRAND must be extracted.
Plus, I need to make a query in a method but problem is I am not sure what kind of data to return.
Function returnBrands() As ??
brands.Fill(db.brands) 'my brandsTableAdapter
Dim q = From pc In db.brands
Select pc.NAME_BRAND, pc.ID_BRAND
Order By NAME_BRAND
Return q
End Function
Visual studio says that q is a kind of
OrderedEnumerableRowCollection(Of <anonymous type: Key NAME_BRAND As String, Key ID_BRAND As String>)
But when I try to return this by the method, it returns an error.
I'm also worried that when the ComboBox correctly loads the NAME_BRANDs, how will I extract the corresponding ID_BRAND after the user will selects a NAME_BRAND?
Thanks for your attention.

Answer 1

Create a type that represents the table you're querying from. Something like this:
Public Class Brand
Public Property ID_BRAND As String
Public Property NAME_BRAND As String
End Class
In the select portion of your query, specify the Brand type and copy the appropriate values:
Dim q = From pc In db.brands
Select New Brand WITH { .ID_BRAND = pc.ID_BRAND, .NAME_BRAND = pc.NAME_BRAND }
Order By NAME_BRAND
Now your function signature looks something like this:
Public Function returnBrands() As IQueryable<Brand>

Answer 2

You can specify which value to show using DisplayMember. You can also keep a value to associate with what you display using ValueMember
.NET has a KeyValuePair(Of TKey,TValue) that is handy for keep a related key and value.
You can use a Dictionary(Of TKey,TValue) to store your ID_BRAND and NAME_BRAND pairs. You can have duplicate NAME_BRANDs but a Dictionary requires the key to be Unique.
For your needs, you can return a Dictionary(Of String, String) from your method and bind it to your ComboBox:
Function returnBrands() As Dictionary(Of String, String)
brands.Fill(db.brands) 'my brandsTableAdapter
Dim q = From pc In db.brands
Select pc.NAME_BRAND, pc.ID_BRAND
Order By NAME_BRAND
Return q.ToDictionary(Of String, String)(Function(x) x.ID_BRAND, Function(x) x.NAME_BRAND)
End Function
Now that you have your dictionary, you can set it as the DataSource of your ComboBox and set the ValueMember and DisplayMember accordingly:
ComboBox1.DataSource = returnBrands()
ComboBox1.DataSource.DisplayMember = "Key"
ComboBox1.DataSource.ValueMember = "Value"
You could also return an object from bind directly to your anonymous type.
Function returnBrands() As Object
brands.Fill(db.brands) 'my brandsTableAdapter
Dim q = From pc In db.brands
Select pc.NAME_BRAND, pc.ID_BRAND
Order By NAME_BRAND
Return q.ToArray()
End Function
ComboBox1.DataSource = returnBrands()
ComboBox1.DisplayMember = "NAME_BRAND"
ComboBox1.ValueMember = "ID_BRAND"
However, the latter approach isn't considered best practice.