Author: Iqbal M. Khan

[Serializable] public class Employees {     // Some of the private data members     // ...     public Employees() {}     // Properties for Employee object     public String     EmployeeId { get; set;}     public String     FirstName { get; set;}     public int        LastName { get; set; }     //... rest of data member properties     // relationship properties     public Employees                Supervisor { get; set;}     public TDBindingList<Employees> Subordinates { get; set;} } public class EmployeesFactory {     public EmployeesFactory() {}     // Methods for EmployeeFactory object     public void       Load (ref Employees emp, int depth) { /* ... */ }     public void       Insert (ref Employees emp, int depth) { /* ... */ }     public void       Update (ref Employees emp, int depth) { /* ... */ }     public void       Delete (ref Employees emp, int depth) { /* ... */ }     // n-1 relationship methods     public void       LoadSupervisor (ref Employees emp, int depth) { /* ... */ }     public void       LoadSubordinates (ref Employees emp, int depth) { /* ... */ } }

The above code includes a domain object called Employees that keeps all the data of an Employee and also its related Employees (supervisor and subordinates). The second object is a persistence class called EmployeesFactory that contains all the code related to the database access. The third class TDBindingList<Employees> is a Generic class provided by TierDeveloper Framework and therefore not described further here.

The above classes need to be called from the GUI in order to implement the functionality.

Steps for Creating Employees Form with Forms Designer

Now that you know what your form should look like and how does the underlying business and data objects look, you're ready to actually design this form. You'll see how easy it is to design this form. Here is step by step instructions on how to go about this.

Step 1: Create Application

Open Visual Studio 2005 and create a new Windows Application using ‘New Project Wizard’.

Step 2: Add References

Before we start working with Forms Designer, we need to add Domain and Persistence objects assembly references to the project. Code in these assemblies is generated by TierDeveloper. To add references, do the following:

1. Open Solution Explorer and right-click on ‘References’ tree node, an ‘Add Reference’ dialog box will appear.

2. Go to the ‘Browse’ tab and browse to the folder Northwind\Data\Persistence\bin, where Northwind is the root folder name of the generated code.

3. Add references of Northwind.Businsess.Domain.dll, Northwind.Data.Persistence.dll and EnterpriseNonServicedLibEval.dll, which you will find in the said folder. Also, browse to the folder where TierDeveloper 6.0 or later is installed and go to bin folder, add reference to TierDeveloper form designer assembly which would be TierDeveloper.Windows.Forms.dll for Windows Forms applications and TierDeveloper.Web.dll for Web/ASP.NET applications.

4. Copy EnterpriseNonServicedLibEval.dll.config and Northwind.Data.Persistence.dll.config file into your application’s output directory. These files contain configuration information that will be used by application to accomplish certain tasks. For example, Northwind.Data.Persistence.dll.config file holds information of databases used in the Persistence layer. Keeping database information in a config file makes our application more flexible. In case of change of database server, we will not have to modify and re-compile the code. Application will work fine with mere modification in the config file.

Step 3: Design Employees Form

Follow these steps to design a form:

1. Open Windows Form ‘Form1’, which will be generated with the creation of new application in Step 1 above.

2. Go to the toolbox, expand TierDeveloper Win tab and drag ‘EditFormManager’ control on the Form.

3. Rename ‘EditFormManager’ to ‘EmployeeEditFormManager’.

4. Click on the arrow appearing on the top right corner of ‘EmployeeEditFormManager’. A menu will appear containing some tasks.

5. Click on ‘Configure Binding’ as shown in the figure below.

Figure 3: Open Forms Designer Menu Configuration

When you do the above, an ‘Object Selection Wizard’ will appear. ‘Object Selection Wizard’ helps in selecting domain and persistence objects for the form. Select Employees object from Northwind.Business.Domain namespace and EmployeesFactory object from Northwind.Data.Persistence namespace through the wizard. Now select the fields, which you want to map against UI controls, from the ‘Available Fields’. Click ‘Add’ button to add the selected fields to the ‘Mapped fields’. Select appropriate UI controls for the mapped fields.

Figure 4: Forms Designer Field Binding Wizard

Next, add the commands by pressing ‘Add’ button on ‘Commands tab’ as shown below. Specify the ‘Control Type’, ‘Target’ and ‘Dependent’ for the command. Here is a brief description of these options.

1. Command Control Type: Type of control you want to create for your command.

2. Command Target: Three types of targets are supported in Forms Designer.

   1. <Persistence Object>: calls a method residing in Persistence layer. You will also have to specify the method type, name and parameters by clicking the button right next to ‘Target’ dropdown for this option.

   2. Form: Opens another Form available in the Application. We can also pass parameters to this Form by clicking the button right next to ‘Target’ dropdown.

   3. Clear Form Command: Resets all the controls available on the Form

3. Dependent Commands: This option is used when you want to trigger another command(s) explicitly after execution of this command.

Figure 5: Forms Designer with Command and Link Binding

Conclusion

As you have seen, TierDeveloper makes it very simple to quickly design and develop rich GUI and connect the underlying business and data objects to it. This is yet another step toward simplifying and speeding up your development time and improving your code quality. Remember, the less code you have to write by hand, the faster your projects are completed and the better is your code quality.