Exercise: Build the Payment Entry application using c# visual studio

In this exercise, you$$ll start to build the application that$$s presented in Chapter $9$ in your textbook, but you$$ll use the existing PayablesData library. As a result, you won$$t have to code the business or database classes. This exercise will demonstrate how the use of object data sources can make it easier for you to build three$-$layer applications.

Start the application and set up the PayablesData library

$1.$ Start a new project named PaymentEntry in your chapter $9$ directory.

$2.$ Add a new class library project to the solution named PayablesData. To do that, you can right$-$click on the solution in the Solution Explorer, select $->,$ click on the Class Library template, and proceed from there.

$3.$ Add the five classes in the PayablesData library that$$s in the PaymentEntry application in the Book applications$\backslash$Chapter $09$ directory to the new PayablesData project. To do that, you can right$-$click on the PayablesData project in the Solution Explorer, select $->,$ and proceed from there.

$4.$ Use the $->$ command to build the PayablesData project and create the DLL file for the class library. $($If you are using C# $2010$ Express Edition, right$-$click on the name of the PayablesData project in the Solution Explorer, then select $$ from the shortcut menu$).$

Build the Vendor Invoices form

$5.$ Use the procedure in figure $9-2$ in your textbook to create an object data source for the Vendor class in the PayablesData library. In the step for selecting the object, click on the Add Reference button and add a reference to the PayablesData library. Then, create a second object data source, this time for the Invoice class.

$6.$ Use the procedure in figure $9-3$ in your textbook to drag the properties for the Vendor class onto the form so they look like the ones in figure $9-6.$ Then, drag the Invoice class onto the form so it creates a DataGridView control like the one that$$s also shown in figure $9-6.$

$7.$ Set the properties for the Name combo box using the procedure shown in figure $4-3$ of chapter $4.$ In this case, you set DataSource to vendorBindingSource, DisplayMember to Name, and ValueMember to VendorID. Also, set the

DropDownStyle property to DropDownList, and be sure to change the

$($DataBindings$)$ Text property to none to remove the binding from the text box portion of the combo box.

$8.$ Test the application to see how it works. At this time, no data is displayed because the business objects that are bound to the controls haven$$t been populated with data.

$9.$ Add the code for the Load event handler that$$s shown in figure $9-12($part $1),$ and add the code for the two methods that it calls. That will populate the business objects. Then, add the event handler for the SelectedIndexChanged event for the Name combo box.

$10.$ Test theapplication to see that the form shows the data for any vendor that you select from the combo box. This should give you some idea of how the use of object data sources can help you build three$-$layer applications more quickly. Build the Payment Entry form and complete the application

$11.$ If you think you can learn more by building the rest of this application, you should be able to do so without much trouble. And if you have problems, you can refer to the complete application in the Book applications$\backslash$Chapter $09$ directory.