Export (0) Print
Expand All

ObjectContext Constructor (String)

Initializes a new instance of the ObjectContext class with the given connection string and default entity container name.

Namespace:  System.Data.Objects
Assembly:  System.Data.Entity (in System.Data.Entity.dll)

'Declaration
Public Sub New ( _
	connectionString As String _
)

Parameters

connectionString
Type: System.String

The connection string, which also provides access to the metadata information.

ExceptionCondition
ArgumentNullException

The connectionString is Nothing.

ArgumentException

The connectionString is invalid.

-or-

The metadata workspace is not valid.

The connectionString is a string that contains information that is required to access a conceptual model and to connect to a data source. The EntityConnectionStringBuilder class can be used to correctly format the string.

The Entity Data Model tools generate a named connection string that is stored in the application's configuration file. This named connection string can be supplied instead of the connectionString parameter when instantiating the ObjectContext class.

The example in this topic is based on the Adventure Works Sales Model. The example shows how to construct an ObjectContext.

' Create the ObjectContext.  
Dim context As New ObjectContext("name=AdventureWorksEntities")

' Set the DefaultContainerName for the ObjectContext. 
' When DefaultContainerName is set, the Entity Framework only 
' searches for the type in the specified container.  
' Note that if a type is defined only once in the metadata workspace 
' you do not have to set the DefaultContainerName.
context.DefaultContainerName = "AdventureWorksEntities" 

Dim query As ObjectSet(Of Product) = context.CreateObjectSet(Of Product)()

' Iterate through the collection of Products.  
For Each result As Product In query
    Console.WriteLine("Product Name: {0}", result.Name)
Next

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5 SP1

.NET Framework Client Profile

Supported in: 4

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Show:
© 2014 Microsoft