How to Access Avalara AvaTax Data Using Entity Framework

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 Avalara AvaTax 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 Avalara AvaTax 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 administrator 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 Avalara AvaTax 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;