IFS开发培训文档(Chapter-08).doc

Title:Date:Page:Solution-Chapter 082005-03-023Document Revision HistoryRevisionDateByRemarksA12005-3-2Henry ZhongCreatedList:Using class utilities1.1 Model Changes1.2 Storage and Business LogicSolutions Chapter 08(Using class utilities)1、 Model Changes1.1 Open the Model and add a new class in the Main diagram. Change the class type to ClassUtility and give the class the name DemoTrInvoiceUtil.1.2 Methods in the DemoTrInvoiceUtil class will use data belonging to the DemoTrInvoice class, hence the dependency relationship between the two classes will need a friendship as well. Therefore the check box Friendship Required in the specification of the relation need to be checked. Check Box must be checked1.3 Now add a public method called GetTotalUnpaid to the DemoTrInvoiceUtil class. This method will retrieve the total value of unpaid invoices for a certain customer. Therefore it needs two arguments. In the detail tab of method specifications add the arguments for CompanyId of type String and CustomerId of type Number. 1.4 The model should look like that following. 1.5 Save the model.2 Storage and Business Logic2.1 The Utility class does not contain any attributes, but contain only methods. Therefore there are no storage changes. Hence can start by opening the source code for DemoTrInvoiceUtil in the business logic.2.2 The following segment of coding, is one possible method of implementing the method Get_Total_Unpaid. Note: One of the conventions used is to use a cursor whenever a select statement is needed.Avoid using PL/SQL procedures in a select statement. The table is used in the place of the view and the column unpaid is used directly instead of using the DEMO_TR_INVOICE_API.Get_Unpaid as these calls to PL/SQL from SQL will cause performance degradation. 2.3 Select the function and click edit. In the edit dialog box that appears select the last tab called PRAGMA, and check the first two options (WNDS- Write No Database State and WNPS- Write No Package State) to assure the security system that these methods will not be updating the database. 2.4 It is possible to test the functionality of this function in a select statement by