How to: Obtain A Context Instance Without Passing A Connection String

This article is relevant to entity models that utilize the deprecated Visual Studio integration of Telerik Data Access. The current documentation of the Data Access framework is available here.

Telerik Data Access can instantiate a context without the need of a connection string. The functionality is applicable only in the cases when at least one instance of the context was already created with a given connection string. It relays on the customized value of the OpenAccessContextBase.CacheKey property and this article demonstrates how to set up your model in order to use it.

1. Add a new class to the project that holds the model called <context_name>.partial.cs (<context_name>.partial.vb). For example: EntitiesModel.partial.cs (EntitiesModels.partial.vb).
2. Make sure that the name of the newly created class, and its definition, and its namespace match exactly those of the generated OpenAccessContext class.

3. In the newly created class, override the CacheKey property so that it returns a value of your own choice (you can also apply some custom computed logic).

   using Telerik.OpenAccess;
   namespace MultipleModels
   {
       public partial class EntitiesModel
       {
           protected override string CacheKey
           {
               get
               {
                   return "my cache key";
               }
           }
       }
   }
   

   Imports Telerik.OpenAccess
   Namespace MultipleModels
       Partial Public Class EntitiesModel
           Protected Overrides ReadOnly Property CacheKey() As String
               Get
                   Return "my cache key"
               End Get
           End Property
       End Class
   End Namespace
   

4. Save the file.

5. Test the set up - at this point, you can instantiate the context for the first time by using one of the Telerik Data Access generated constructors and for the next times by passing String.Empty to the EntitiesModel(string connection) constructor. For example:

   string connectionString = @"SofiaCarRentalConnection";
       using (EntitiesModel dbContext = new EntitiesModel(connectionStringName))
       {
           //TODO: Execute Context Logic
       }
       using (EntitiesModel dbContext = new EntitiesModel(String.Empty))
       {
           //TODO: Execute Additional Context Logic
       }
   

   Dim connectionString As String = "SofiaCarRentalConnection"
       Using dbContext As New EntitiesModel(connectionStringName)
           'TODO: Execute Context Logic
       End Using
       Using dbContext As New EntitiesModel(String.Empty)
           'TODO: Execute Additional Context Logic
       End Using