Ready to get started?

Learn more about Connectivity Solutions

Learn More

Access Data with Entity Framework 6

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

Entity Framework is an object-relational mapping framework that can be used to work with data as objects. While you can run the ADO.NET Entity Data Model wizard in Visual Studio to handle generating the Entity Model, this approach, the model-first approach, can put you at a disadvantage if there are changes in your data source or if you want more control over how the entities operate. In this article you will complete the code-first approach to accessing data using the CData ADO.NET Provider.

  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 Entity Framework 6 assembly and the connection string.

    The primary method for performing basic authentication is to provide your login credentials, as follows:

    • User: Set this to your username.
    • Password: Set this to your password.

    Optionally, if you are making use of a sandbox environment, set the following:

    • UseSandbox: Set this to true if you are authenticating with a sandbox account.

    Authenticating Using Account Number and License Key

    Alternatively, you can authenticate using your account number and license key. Connect to data using the following:

    • AccountId: Set this to your Account Id. The Account Id is listed in the upper right hand corner of the admin console.
    • LicenseKey: Set this to your Avalara Avatax license key. You can generate a license key by logging into Avalara Avatax as an account adminstrator and navigating to Settings -> Reset License Key.
    <configuration> ... <connectionStrings> <add name="AvalaraAvataxContext" connectionString="Offline=False;User=MyUser;Password=MyPassword;" providerName="System.Data.CData.AvalaraAvatax" /> </connectionStrings> <entityFramework> <providers> ... <provider invariantName="System.Data.CData.AvalaraAvatax" type="System.Data.CData.AvalaraAvatax.AvalaraAvataxProviderServices, System.Data.CData.AvalaraAvatax.Entities.EF6" /> </providers> <entityFramework> </configuration> </code>
  4. Add a reference to System.Data.CData.AvalaraAvatax.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 AvalaraAvataxContext. 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 AvalaraAvataxContext : DbContext { public AvalaraAvataxContext() { } protected override void OnModelCreating(DbModelBuilder modelBuilder) { // To remove the requests to the Migration History table Database.SetInitializer<AvalaraAvataxContext>(null); // To remove the plural names modelBuilder.Conventions.Remove<PluralizingTableNameConvention>(); } }
  7. Create another .cs file and name it after the entity you are retrieving, for example, Transactions. 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("Transactions")] public class Transactions { [System.ComponentModel.DataAnnotations.Key] public System.String Id { get; set; } public System.String TotalTax { get; set; } }
  8. Now that you have created an entity, add the entity to your context class: public DbSet<Transactions> Transactions { set; get; }
  9. With the context and entity finished, you are now ready to query the data in a separate class. For example: AvalaraAvataxContext context = new AvalaraAvataxContext(); context.Configuration.UseDatabaseNullSemantics = true; var query = from line in context.Transactions select line;