Databases Reference
In-Depth Information
Validation Rule Design
To find a reasonable compromise between code reuse, complexity, and performance,
without having to do a lot of refactoring later, try the following rules of thumb when
designing validation logic in your application:
.
Implement persistence validation rules with data annotations
.
Make state properties of entities read-only
.
Implement state transitions and validation in business rule methods
.
Implement state-specific persistence validation in separate validation methods
Implement Persistence Validation Rules with Data Annotations
The validation framework discussed in Chapter 8 offers a great way to implement persis-
tence validation rules by applying pre-built validation attributes or writing custom valida-
tion methods for individual properties or entire entities. You can quickly apply the
RequiredAttribute
to the shipping address properties of the Order entity to ensure that
the order is valid before saving it to the database.
Make State Properties of Entities Read-Only
You do not want the users of your application (neither the customers nor the employees)
to edit the
OrderStatus
property directly, even if they initiate the state transition.
Customers will submit orders by clicking a Submit button on a check-out page, and a
background process handling credit card payments will mark the orders as paid. The best
way to ensure that state properties of an entity cannot be changed through the user inter-
face of the application is to make them read-only.
With Entity Framework, you can use the Entity Designer to make the setter of the
OrderStatus
property
internal
, as shown in Figure 9.7.
