Defining Entities › Defining the Project Entity › Using Inheritance to Define the Project Entity

Using Inheritance to Define the Project Entity

You have now defined the fields in which the Project entity will store data, and specified the class library fields from which those fields inherit. In this next step, you give the Project entity a user interface and functionality to interact with a database.

You again use inheritance to add this functionality. The inheritance triple gives your entity the objects necessary to display and process a user interface, and to read data from and write data to a database.

To add functionality to the Project entity:

1. Click the Entity button on the Object Browser.

   Notice that there is no plus sign to the left of the Project entity. This tells you that there are no objects scoped to it.

2. Drag Project from the Object Browser to the source object field of the Model Editor.
3. From the verb list, select is a ENT.
4. In the target object field, enter Grid Maintained Entity and press Enter.

   You just created the triple Project is a OBASE/Grid Maintained Entity. This indicates that Project inherits the structure and functionality of the Grid Maintained Entity object in the OBASE class library.

   For more information on defining entities, look in the online help index. For information on the Grid Maintained Entity object, select the pattern in the Object Browser and press Shift+F1.

   

5. By inheriting from Grid Maintained Entity, the Project entity now has some scoped objects. In the Object Browser, click the Refresh button.
6. The Project entity you just created appears at the top of the Object Browser. Click the plus sign to the left of the entity icon to expand Project:

   

   You can see that among the objects it inherited are several functions (with scoped panels) and views, and a physical table. These objects enable Project to display a user interface, and to store data to and retrieve data from a database.

   Specifically:

• Project.Grid Maintenance Suite.Edit Grid User Interface displays the panel scoped to it
• List Panel, which is scoped to the Edit Grid User Interface function, stores the layout of the Edit Project panel
• The functions scoped to the views access the database to add, delete, and change records

  You will learn more about panels in Modifying the User Interface, and functions and views in the chapter "Defining Owned By Relationships."