wwBusinessObject Examples

The following are a few simple examples of using wwBusinessObject based on the following class:

DEFINE CLASS cCustomer AS wwBusinessObject

cAlias = "Customers"
cFilename = "Customers"
cPkField = "Id"

************************************************************************
*  CreateNewId
****************************************
***  Function: Overridden from base to create Character key
***    Assume: If you don't override this method the assumed
***            type is integer and generating via lookup table
***    Return: new Character id
************************************************************************
FUNCTION CreateNewId()
RETURN SYS(2015)
ENDFUNC
*   CreateNewId

************************************************************************
*  Validate
****************************************
***  Function: Overrides Validation return .T. or .F. and set
***            .oValidationErrors collection via `.AddValidationError()`
***    Return: .T. or .F.
************************************************************************
FUNCTION Validate()

THIS.oValidationErrors.Clear()

IF EMPTY(THIS.oData.Company)
   THIS.AddValidationError("Company can't be empty","Company")
ENDIF

RETURN this.oValidationErrors.Count > 0
ENDFUNC
*   Validate

ENDDEFINE

Note you typically subclass wwBusinessObject and match it to a business entity that acts as a base of the business object. This doesn't have to be a one-to-one mapping - some business objects can represent complex objects like Order with subobjects for Customer and LineItems. The above is a simple business object mapped to a single object.

Queries

You can query data using the Query method, which lets you execute provider independent query. Assuming your queries work cross providers, a single query can be run against Fox data or Sql Server (or other ODBC backend) dependent on the .nDataMode property.

Queries can be partial using just a WHERE clause or SELECT <fieldListOr*> and the FROM or SELECT and INTO clauses are automatically filled in.

FUNCTION Query()

loBus = CREATEOBJECT("cCustomer")

*** Get all records
lnResult = loBus.Query()   && select * / TQUery
this.AssertTrue(lnResult > 0)
this.MessageOut(TRANSFORM(lnResult) + " records queried")

*** Get filtered records with augmented syntax (ie. no FROM clause)
lnResult = loBus.Query([Where company = "West Wind"],"TCustomers")   && Select *
this.AssertTrue(lnResult == 1)
this.MessageOut(TRANSFORM(lnResult) + " records queried for West Wind")

*** Explicit SQL
lnResult = loBus.Query([Select id,company Where company = "West Wind"],"TCustomers") 
this.AssertTrue(lnResult == 1)
this.MessageOut(TRANSFORM(lnResult) + " records queried for West Wind")

You should minimize using explicit query commands in your client code however and create specialized methods in the business object to return data. For example, in the cCustomer class i may have a method called GetRecentCustomers() that I just pass a date to. The method would then create the appropriate SQL command to call with the Query method:

FUNCTION GetRecentCustomers(ldDate as DateTime) as Integer
RETURN THIS.Query( "SELECT * where Updated > ?ldDate", "TCustomers"  )
ENDFUNC

While this is a very simple example, even so it isolates the code in a single, logical location which makes this code easier to find and debug if something doesn't work or later needs to be updated.

Load and Save Entity Data

It's easy to load entity data, make changes and save it.

FUNCTION LoadAndSave()

lcCompany = "East Wind Trade Company"
loBus = CREATEOBJECT("cCustomer")

*** Load a specific record
this.AssertTrue(loBus.Load("_4FG12Y7UD"))

loBus.oData.Company = lcCompany
loBus.oData.Updated = DATETIME()

this.AssertTrue(loBus.Save())
ENDFUNC

Add and Delete Entities

It's just as easy to create a new entity, fill it with data, then save it.

loBus = CREATEOBJECT("cCustomer")

*** Add a new Entity
loBus.New()
loBus.oData.Company = "East India Deliveries"
loBus.oData.FirstName = "Gaal"
loBus.oData.LastName = "Dornick"
loBus.oData.BillRate = 150
loBus.oData.Entered = DateTime()
this.AssertTrue(loBus.Save(),"Couldn't save new entity.")

*** Capture the Pk for new entity
lcId = loBus.oData.Id

*** Remove the newly created entity
this.AssertTrue(loBus.Delete(lcId))