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LINQ to USPS Data

LINQ provides general-purpose query facilities in .NET Framework 3.0 and above and provides one easy way to programmatically access data through from CData ADO.NET Data Providers. This example uses LINQ to access information from the USPS Data Provider.

This article demonstrates how to use LINQ to access USPS tables through the CData ADO.NET Data Provider for USPS. To do this you will LINQ to Entity Framework, which is used to generate the connection and can be used with any CData ADO.NET Data Providers to access data via LINQ.

See the help documentation for a guide to setting up an EF 6 project to use the provider.

  1. In a new project in Visual Studio, right-click on the project and choose to add a new item. Add an ADO.NET Entity Data Model.
  2. Choose EF Designer from Database and click Next.
  3. Add a new Data Connection, and change your data source type to "CData USPS Data Source".
  4. Enter your data source connection information.

    To authenticate with USPS, set the following connection properties.

    • PostageProvider: The postage provider to use to process requests. Available options are ENDICIA and STAMPS. If unspecified, this property will default to ENDICIA.
    • UseSandbox: This controls whether live or test requests are sent to the production or sandbox servers. If set to true, the Password, AccountNumber, and StampsUserId properties are ignored.
    • StampsUserId: This value is used for logging into authentication to the Stamps servers. This value is not applicable for Endicia and is optional if UseSandbox is true.
    • Password: This value is used for logging into Endicia and Stamps servers. If the postage provider is Endicia, this will be the pass phrase associated with your postage account. It is optional if UseSandbox is true.
    • AccountNumber: The shipper's account number. It is optional if UseSandbox is true.
    • PrintLabelLocation: This property is required to use the GenerateLabels or GenerateReturnLabels stored procedures. This should be set to the folder location where generated labels should be stored.

    The Cache Database

    Many of the useful task available from USPS require a lot of data. To ensure this data is easy to input and recall later, utilize a cache database to make requests. Set the cache connection properties in order to use the cache:

    • CacheLocation: The path to the cache location, for which a connection will be configured with the default cache provider. For example, C:\users\username\documents\uspscache

    As an alternative to CacheLocation, set the combination of CacheConnection and CacheProvider to configure a cache connection using a provider separate from the default.

    Below is a typical connection string:

    PostageProvider=ENDICIA; RequestId=12345; Password='abcdefghijklmnopqr'; AccountNumber='12A3B4C'
  5. If saving your entity connection to App.Config, set an entity name. In this example we are setting USPSEntities as our entity connection in App.Config.
  6. Enter a model name and select any tables or views you would like to include in the model.

Using the entity you created, you can now perform select, update, delete, and insert commands. For example:

USPSEntities context = new USPSEntities(); var sendersQuery = from senders in context.Senders select senders; foreach (var result in sendersQuery) { Console.WriteLine("{0} {1} ", result.Id, result.FirstName); }

See "LINQ and Entity Framework" chapter in the help documentation for example queries of the supported LINQ.