How to Access TaxJar 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 TaxJar 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 TaxJar Entity Framework 6 assembly and the connection string.

   To authenticate to the TaxJar API, first obtain the API Key from the TaxJar UI.

   NOTE: the API is available only for Professional and Premium TaxJar plans.

   If you already have a Professional or Premium plan you can find the API Key by logging in the TaxJar UI and navigating to Account -> TaxJar API. After obtaining the API Key, you can set it in the APIKey connection property.

   Additional Notes

   • By default, the CData connector will retrieve data of the last 3 months in cases where the entity support date range filtering. You can set StartDate to specify the minimum creation date of the data retrieved.
   • If the API Key has been created for a sandbox API account please set UseSandbox to true, but not all endpoints will work as expected. For more information, refer to the TaxJar developer documentation.

   <configuration>
    ... 
    <connectionStrings>
    <add name="TaxJarContext" connectionString="Offline=False;APIKey=3bb04218ef8t80efdf1739abf7257144;" providerName="System.Data.CData.TaxJar" />
    </connectionStrings>
    <entityFramework>
    <providers>
    ... 
    <provider invariantName="System.Data.CData.TaxJar" type="System.Data.CData.TaxJar.TaxJarProviderServices, System.Data.CData.TaxJar.Entities.EF6" />
    </providers>
    <entityFramework>
   </configuration>
   </code> 
   

4. Add a reference to System.Data.CData.TaxJar.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 TaxJarContext. 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 TaxJarContext : DbContext {
    public TaxJarContext() { }
   
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
    // To remove the requests to the Migration History table
    Database.SetInitializer<TaxJarContext>(null); 
    // To remove the plural names 
    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();
    } 
   }
   

7. Create another .cs file and name it after the TaxJar entity you are retrieving, for example, Orders. 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("Orders")]
   public class Orders {
    [System.ComponentModel.DataAnnotations.Key] 
    public System.String TransactionID { get; set; }
    public System.String UserID { get; set; }
   }
    
   

8. Now that you have created an entity, add the entity to your context class:

   public DbSet<Orders> Orders { set; get; }
   

9. With the context and entity finished, you are now ready to query the data in a separate class. For example:

   TaxJarContext context = new TaxJarContext();
   context.Configuration.UseDatabaseNullSemantics = true;
   var query = from line in context.Orders select line;