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Step 1: Add an EAnnotation to the appropriate EClass.

Right-click on the EClass in the editor and add an EAnnotation. Set the source attribute to http://www.eclipse.org/emf/2002/Ecore. Then add a key/value pair, with constraints as the key and the logical name of the constraint (a valid Java name) as the value. If you need to add several constraints, separate their names with a space.

Step 2: Generate code and locate the validation method stub(s)

Genmodel will generate an EValidator subclass in the util package with one method for each constraints (if there are any) . An example of the generated stub is shown right.named validator_<constraint name>. The method body contains template code for adding a diagnostic for a violated constraint with ERROR severity. The condition is initially false and needs to be replaced by the real constraint logic. An example of the generated stub is shown right.

 

Step 3: Implement the constraint logic in Java

The false condition has been replaced by a call to the hasOnlyNameCharacters helper method. You may also lower the severity if the constraint is more of a suggestion. Notice how NOT is added after @generated, to indicate that we've change generated code. This will prevent the code from being overwritten if the class is regenerated.

Code Block
	/**
	 * Validates the nameCharacters constraint of '<em>Person</em>'.
	 * <!-- begin-user-doc -->
	 * <!-- end-user-doc -->
	 * @generated NOT
	 */

	public boolean validatePerson_nameCharacters(Person person, ...) {
		if (! hasOnlyNameCharacters(person.getName())) {
			if (diagnostics != null) {
				...
			}
			return false;
		}
		return true;
	}

	private boolean hasOnlyNameCharacters(String name) {
		for (int i = 0; i < name.length(); i++) {
			char c = name.charAt(i);
			if (! (Character.isLetter(c) || c == ' ' || c == '-')) {
				return false;
			}
		}
		return true;
	}

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