linneo

Annotations

Four annotations in io.github.devbpm.linneo.annotation declare what a data model holds. All are @Documented, @Retention(RUNTIME) and @since 0.1.0. They are read by the Classifier, which never reads field values.

Annotation	Target	Declares	Page
@Category	field, record component	the data category of one field, optionally with stricter levels and its identifiability	category.md
@DefaultCategory	type	the non-personal category of every unannotated field of a class, with the reason	default-category.md
@CategoryByRow	field, record component	a field whose category depends on each row, with the most protective category a row may hold	category-by-row.md
@Exempt	field, record component	a field that holds no data of the model, with the reason	exempt.md

On a record component, the annotations also apply to the component’s field, which is what the classifier reads.

Which fields are classified

The classifier walks the class and its superclasses (stopping before Object, Record and Enum) and considers every field declared by them except static, transient and synthetic fields (and those named $$_..., added by Hibernate), which are always skipped without any annotation. See Classifier.

Resolution order

For each considered field, the first rule that applies wins:

#	Rule	Result (FieldClassification.basis())
1	The field has @Exempt	skipped: no classification
2	The field has @Category	the declared category (DECLARED)
2	The field has @CategoryByRow	the ceiling category (BY_ROW)
3	The class that declares the field has @DefaultCategory	that default (CLASS_DEFAULT)
4	The class being classified has @DefaultCategory	that default (CLASS_DEFAULT)
5	none of the above	error UNCLASSIFIED_FIELD

Consequences:

• An annotation on a field always overrides a class default.
• A superclass’s @DefaultCategory covers the fields that superclass declares, even when you classify a subclass.
• A subclass’s @DefaultCategory covers the fields it declares and the unannotated fields inherited from superclasses that have no default of their own.
• @DefaultCategory is not inherited: a subclass without its own default does not get its superclass’s default for the fields the subclass declares.
• A deprecated key in any annotation still classifies the field, with the current replacement, and produces a DEPRECATED_CATEGORY warning.

Conflicts

Combination on one field	Violation	Effect
@Exempt + @Category and/or @CategoryByRow	CONFLICTING_ANNOTATIONS: @Exempt cannot be combined with @Category or @CategoryByRow	field skipped (the @Exempt reason is still checked)
@Category + @CategoryByRow	CONFLICTING_ANNOTATIONS: @Category and @CategoryByRow cannot be used together	field not classified
@Category or @CategoryByRow + class @DefaultCategory	none	the field annotation wins

All conflicts are errors. See Violations for every code.

Example

import io.github.devbpm.linneo.annotation.*;
import static io.github.devbpm.linneo.Categories.*;

@DefaultCategory(value = SYSTEM_CONFIGURATION, reason = "menu configuration")
public class MenuGroup {
    private String code;                      // CLASS_DEFAULT: system.configuration
    private String label;                     // CLASS_DEFAULT: system.configuration

    @Category(USER_UNIQUE_ID)                 // DECLARED: overrides the class default
    private Long createdBy;

    @Exempt("computed from code")
    private String displayKey;                // skipped

    private transient String cache;           // skipped: transient
}

See also: @Category · @DefaultCategory · @CategoryByRow · @Exempt · Classifier · course: Annotating models

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