3. Make an Entity Class Model
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3. Make an Entity Class Model

Using the information design model shown in Figure 7.2 above as the starting point, we make an Entity class model with getters/setters and corresponding Java datatypes.

Figure 9.1. Deriving an Entity class model from an information design model

Deriving an Entity class model from an information design model
Deriving an Entity class model from an information design model
Deriving an Entity class model from an information design model

The entity class model defines getters and setters for all properties and the following property constraint annotations:

  1. Using @Id and @NotNull, the isbn attribute is declared to be a standard identifier, implying that it is mandatory and unique.

  2. Using @Pattern("\\b\\d{10}\\b"), the isbn attribute has a pattern constraint requiring its values to match the ISBN-10 format (simplified to the case of 10-digit strings).

  3. Using @NotNull and @Size( max=50), the title attribute is mandatory and has a string length maximum constraint of at most 50 characters.

  4. Using @NotNull, @Min( 1459) and the custom annotation @UpToNextYear, the year attribute is mandatory and has an interval constraint of a special form where the minimum is 1459 and the maximum is not fixed, but provided by a custom annotation implementing the calendar arithmetic function nextYear().

Since there is no predefined Bean Validation annotation for checking the uniqueness of an ID value provided when creating a new entity object, we define a static method checkIsbnAsId that can be invoked in a corresponding controller method when creating a new entity object.

In addition, the entity class model defines the static CRUD data management methods retrieveAll, create, update and delete.

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2. New Issues Home 4. Write the Model Code