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LINQ to Google Cloud Storage 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 Google Cloud Storage Data Provider.

This article demonstrates how to use LINQ to access Google Cloud Storage tables through the CData ADO.NET Data Provider for Google Cloud Storage. 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 Google Cloud Storage Data Source".
  4. Enter your data source connection information.

    Authenticate with a User Account

    You can connect without setting any connection properties for your user credentials. After setting InitiateOAuth to GETANDREFRESH, you are ready to connect.

    When you connect, the Google Cloud Storage OAuth endpoint opens in your default browser. Log in and grant permissions, then the OAuth process completes

    Authenticate with a Service Account

    Service accounts have silent authentication, without user authentication in the browser. You can also use a service account to delegate enterprise-wide access scopes.

    You need to create an OAuth application in this flow. See the Help documentation for more information. After setting the following connection properties, you are ready to connect:

    • InitiateOAuth: Set this to GETANDREFRESH.
    • OAuthJWTCertType: Set this to "PFXFILE".
    • OAuthJWTCert: Set this to the path to the .p12 file you generated.
    • OAuthJWTCertPassword: Set this to the password of the .p12 file.
    • OAuthJWTCertSubject: Set this to "*" to pick the first certificate in the certificate store.
    • OAuthJWTIssuer: In the service accounts section, click Manage Service Accounts and set this field to the email address displayed in the service account Id field.
    • OAuthJWTSubject: Set this to your enterprise Id if your subject type is set to "enterprise" or your app user Id if your subject type is set to "user".
    • ProjectId: Set this to the Id of the project you want to connect to.

    The OAuth flow for a service account then completes.

    Below is a typical connection string:

    ProjectId='project1';InitiateOAuth=GETANDREFRESH
  5. If saving your entity connection to App.Config, set an entity name. In this example we are setting GoogleCloudStorageEntities 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 commands. For example:

GoogleCloudStorageEntities context = new GoogleCloudStorageEntities(); var bucketsQuery = from buckets in context.Buckets select buckets; foreach (var result in bucketsQuery) { Console.WriteLine("{0} {1} ", result.Id, result.Name); }

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