Access IBM Cloud Object Storage Data with Entity Framework 6

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This article shows how to access IBM Cloud Object Storage data using an Entity Framework code-first approach. Entity Framework 6 is available in .NET 4.5 and above.

Microsoft Entity Framework serves as an object-relational mapping framework for working with data represented as objects. Although Visual Studio offers the ADO.NET Entity Data Model wizard to automatically generate the Entity Model, this model-first approach may present challenges when your data source undergoes changes or when you require greater control over entity operations. In this article, we will delve into the code-first approach for accessing IBM Cloud Object Storage data through the CData ADO.NET Provider, providing you with more flexibility and control.

  1. Open Visual Studio and create a new Windows Form Application. This article uses a C# project with .NET 4.5.
  2. Run the command 'Install-Package EntityFramework' in the Package Manger Console in Visual Studio to install the latest release of Entity Framework.
  3. Modify the App.config file in the project to add a reference to the IBM Cloud Object Storage Entity Framework 6 assembly and the connection string.

    Register a New Instance of Cloud Object Storage

    If you do not already have Cloud Object Storage in your IBM Cloud account, follow the procedure below to install an instance of SQL Query in your account:

    1. Log in to your IBM Cloud account.
    2. Navigate to the page, choose a name for your instance and click Create. You will be redirected to the instance of Cloud Object Storage you just created.

    Connecting using OAuth Authentication

    There are certain connection properties you need to set before you can connect. You can obtain these as follows:

    API Key

    To connect with IBM Cloud Object Storage, you need an API Key. You can obtain this as follows:

    1. Log in to your IBM Cloud account.
    2. Navigate to the Platform API Keys page.
    3. On the middle-right corner click "Create an IBM Cloud API Key" to create a new API Key.
    4. In the pop-up window, specify the API Key name and click "Create". Note the API Key as you can never access it again from the dashboard.

    Cloud Object Storage CRN

    If you have multiple accounts, you will need to specify the CloudObjectStorageCRN explicitly. To find the appropriate value, you can:

    • Query the Services view. This will list your IBM Cloud Object Storage instances along with the CRN for each.
    • Locate the CRN directly in IBM Cloud. To do so, navigate to your IBM Cloud Dashboard. In the Resource List, Under Storage, select your Cloud Object Storage resource to get its CRN.

    Connecting to Data

    You can now set the following to connect to data:

    • InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to avoid repeating the OAuth exchange and manually setting the OAuthAccessToken.
    • ApiKey: Set this to your API key which was noted during setup.
    • CloudObjectStorageCRN (Optional): Set this to the cloud object storage CRN you want to work with. While the connector attempts to retrieve this automatically, specifying this explicitly is recommended if you have more than Cloud Object Storage account.

    When you connect, the connector completes the OAuth process.

    1. Extracts the access token and authenticates requests.
    2. Saves OAuth values in OAuthSettingsLocation to be persisted across connections.
    <configuration> ... <connectionStrings> <add name="IBMCloudObjectStorageContext" connectionString="Offline=False;ApiKey=myApiKey;CloudObjectStorageCRN=MyInstanceCRN;Region=myRegion;OAuthClientId=MyOAuthClientId;OAuthClientSecret=myOAuthClientSecret;" providerName="System.Data.CData.IBMCloudObjectStorage" /> </connectionStrings> <entityFramework> <providers> ... <provider invariantName="System.Data.CData.IBMCloudObjectStorage" type="System.Data.CData.IBMCloudObjectStorage.IBMCloudObjectStorageProviderServices, System.Data.CData.IBMCloudObjectStorage.Entities.EF6" /> </providers> <entityFramework> </configuration> </code>
  4. Add a reference to System.Data.CData.IBMCloudObjectStorage.Entities.EF6.dll, located in the lib -> 4.0 subfolder in the installation directory.
  5. Build the project at this point to ensure everything is working correctly. Once that's done, you can start coding using Entity Framework.
  6. Add a new .cs file to the project and add a class to it. This will be your database context, and it will extend the DbContext class. In the example, this class is named IBMCloudObjectStorageContext. The following code example overrides the OnModelCreating method to make the following changes:
    • Remove PluralizingTableNameConvention from the ModelBuilder Conventions.
    • Remove requests to the MigrationHistory table.
    using System.Data.Entity; using System.Data.Entity.Infrastructure; using System.Data.Entity.ModelConfiguration.Conventions; class IBMCloudObjectStorageContext : DbContext { public IBMCloudObjectStorageContext() { } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // To remove the requests to the Migration History table Database.SetInitializer<IBMCloudObjectStorageContext>(null); // To remove the plural names modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } }
  7. Create another .cs file and name it after the IBM Cloud Object Storage entity you are retrieving, for example, Objects. In this file, define both the Entity and the Entity Configuration, which will resemble the example below: using System.Data.Entity.ModelConfiguration; using System.ComponentModel.DataAnnotations.Schema; [System.ComponentModel.DataAnnotations.Schema.Table("Objects")] public class Objects { [System.ComponentModel.DataAnnotations.Key] public System.String Key { get; set; } public System.String Etag { get; set; } }
  8. Now that you have created an entity, add the entity to your context class: public DbSet<Objects> Objects { set; get; }
  9. With the context and entity finished, you are now ready to query the data in a separate class. For example: IBMCloudObjectStorageContext context = new IBMCloudObjectStorageContext(); context.Configuration.UseDatabaseNullSemantics = true; var query = from line in context.Objects select line;