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

   Connect using the API Token

   You can connect to Wave Financial by specifying the APIToken You can obtain an API Token using the following steps:

   1. Log in to your Wave account and navigate to "Manage Applications" in the left pane.
   2. Select the application that you would like to create a token for. You may need to create an application first.
   3. Click the "Create token" button to generate an APIToken.

   Connect using OAuth

   If you wish, you can connect using the embedded OAuth credentials. See the Help documentation for more information.

   <configuration>
    ... 
    <connectionStrings>
    <add name="WaveFinancialContext" connectionString="Offline=False;InitiateOAuth=GETANDREFRESH;" providerName="System.Data.CData.WaveFinancial" />
    </connectionStrings>
    <entityFramework>
    <providers>
    ... 
    <provider invariantName="System.Data.CData.WaveFinancial" type="System.Data.CData.WaveFinancial.WaveFinancialProviderServices, System.Data.CData.WaveFinancial.Entities.EF6" />
    </providers>
    <entityFramework>
   </configuration>
   </code> 
   

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

7. Create another .cs file and name it after the Wave Financial entity you are retrieving, for example, Invoices. 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("Invoices")]
   public class Invoices {
    [System.ComponentModel.DataAnnotations.Key] 
    public System.String Id { get; set; }
    public System.String DueDate { get; set; }
   }
    
   

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

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

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

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