How do I use LINQ to Entities in Visual Basic?

问题

I've created a .NET solution with two projects:

1. ToyData (Visual Basic Class Library)

2. ToyOne (Visual Basic WPF Application)

The ToyData project contains Toy.edmx, an ADO.NET Entity Data Model generated from a database called Toy.

The ToyOne project contains this Window1.xaml.vb file:

1   Imports ToyData
2   
3   Class Window1
4   
5       Private Sub Window1_Loaded( _
6       ByVal sender As System.Object, _
7       ByVal e As System.Windows.RoutedEventArgs) _
8       Handles MyBase.Loaded
9   
10          Dim dc As New ToyEntities
11          Label1.Content = (From c As Client In dc.ClientSet _
12                            Select c).First
13  
14      End Sub
15  
16  End Class

It throws this run-time exception in the auto-generated Toy.Designer.vb file:

The specified named connection is either not found in the configuration,  
not intended to be used with the EntityClient provider, or not valid.

What am I doing wrong?

回答1:

I've seen this issue before between a service project and a test project (that uses the data objects defined in the service).

---

If you right click on "new ToyEntities" and go to definition, and keep drilling in... you'll get to some auto-generated code that fetches a connection string from a config file.

Check the ToyData project for a config file. Copy the values into an App.Config file (it may not exist yet) for the other project.

来源：https://stackoverflow.com/questions/260179/how-do-i-use-linq-to-entities-in-visual-basic