To Insert Reusable Business Logic That Has Already Been Declared

Review the generic graph extension that provides the business logic that you want to reuse as follows:

Identify the mapped cache extensions the generic graph extension works with and the list of their fields, and decide whether the default mapping (which is defined by the mapping class of the generic graph extension) is suitable for the base data access class (DAC) that you are going to use.
Identify the fields of the mapped cache extension that are bound to columns of a database table, and make sure the database table that corresponds to the base DAC includes the columns to store the data from the mapped cache extension.

In the code of the graph you need to add the reusable business logic to, add the public implementation class that derives from the generic graph extension of the needed type. Use the following types in the type parameters of the generic graph extension:

The base graph to which you add reusable logic
The main DAC of the primary data view of the base graph

In the following code, the MultiCurrency class extends the OpportunityMaint graph. The MultiCurrency class derives from

public abstract class MultiCurrencyGraph<TGraph,
                        TPrimary> :
                    PXGraphExtension<TGraph>

.

public class MultiCurrency : MultiCurrencyGraph<OpportunityMaint, CROpportunity>
{
}

In the added class, override the abstract methods of the generic graph extension as follows:

In the overridden methods of the generic graph extension that return the mapping classes, either use the default mapping of the fields of the mapped cache extension to the fields of the base DAC or adjust the mapping.
In the other overridden methods, implement the required business logic. For details on the implementation of the methods in the generic graph extension declared in MYOB Acumatica, see API Reference.

In the added class, adjust the reused business logic by doing any of the following:

Override other methods of the base class.
Add your own views, methods, and event handlers.

The following code shows a sample implementation of the MultiCurrency class, which reuses the multicurrency business logic defined in the MultiCurrencyGraph generic graph extension.

public class MultiCurrency : MultiCurrencyGraph<OpportunityMaint, CROpportunity>
{   
  protected override DocumentMapping GetDocumentMapping()
  {
    return new DocumentMapping(typeof(CROpportunity)) 
    {
      DocumentDate =  typeof(CROpportunity.closeDate)
    };
  }  

  protected override CurySourceMapping GetCurySourceMapping()
  {
    return new CurySourceMapping(typeof(Customer));
  }

  public PXSelect<CRSetup> crCurrency;
  protected PXSelectExtension<CurySource> SourceSetup => 
   new PXSelectExtension<CurySource>(crCurrency);

  protected virtual CurySourceMapping GetSourceSetupMapping()
  { 
    return new CurySourceMapping(typeof(CRSetup)) 
    {
      CuryID = typeof(CRSetup.defaultCuryID), 
       CuryRateTypeID = typeof(CRSetup.defaultRateTypeID)
    };        
  }

  protected override CurySource CurrentSourceSelect()
  {
    ...
  }
}

To Insert Reusable Business Logic That Has Already Been Declared

To Add a Generic Graph Extension to a Graph