[forge-issues] [JBoss JIRA] (FORGE-1616) Command constraint-new-constraint to create a new constraint

[George Gastaldi (JIRA)]

     [ https://issues.jboss.org/browse/FORGE-1616?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

George Gastaldi updated FORGE-1616:
-----------------------------------

    Component/s: Java EE
                     (was: Scaffold)

    
> Command constraint-new-constraint to create a new constraint
> ------------------------------------------------------------
>
>                 Key: FORGE-1616
>                 URL: https://issues.jboss.org/browse/FORGE-1616
>             Project: Forge
>          Issue Type: Sub-task
>          Components: Java EE
>    Affects Versions: 2.1.1.Final
>            Reporter: Antonio Goncalves
>             Fix For: 2.x Future
>
>
> This allows the developer to create a constraint (with or without implementation) with a default error message (as a resource bundle). 
> h2. Constraint with no implementation
> The following command will create a *constraint annotation* with no  implementation, and a default *error message* :
> {code}
> constraint-new-constraint --named URL
> {code}
> This command first creates the constraint annotation (notice validatedBy = {})
> {code}
> @Documented
> @Constraint(validatedBy = {})
> @Target( { METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
> @Retention(RUNTIME)
> @ReportAsSingleViolation
> public @interface URL {
> 	String message() default "{org.mycompany.myproject.constraints.URL.message}";
> 	Class<?>[] groups() default { };
> 	Class<? extends Payload>[] payload() default { };
> 	@Target( { METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
> 	@Retention(RUNTIME)
> 	@Documented
> 	public @interface List {
> 		URL[] value();
> 	}
> }
> {code}
> Then, it creates a message entry in the {{ValidationMessages.properties}} file (the file is created under {{resources}} directory if it doesn't already exist)
> {code}
> org.mycompany.myproject.constraints.URL.message=invalid URL
> {code}
> We could have attributes to the command to change the target
> {code}
> constraint-new-constraint --named URL --targets METHOD FIELD
> {code}
> This will generate the following code only with @Target METHOD, FIELD
> {code}
> @Documented
> @Constraint(validatedBy = {})
> @Target( { METHOD, FIELD })
> @Retention(RUNTIME)
> @ReportAsSingleViolation
> public @interface URL {
> 	String message() default "{org.mycompany.myproject.constraints.URL.message}";
> 	Class<?>[] groups() default { };
> 	Class<? extends Payload>[] payload() default { };
> 	@Target( { METHOD, FIELD })
> 	@Retention(RUNTIME)
> 	@Documented
> 	public @interface List {
> 		URL[] value();
> 	}
> }
> {code}
>  
> h2. Constraint with an implementation
> The {{constraint-new-constraint}} can have a {{validatedBy}} and a {{type}} attribute, it will then create a *constraint annotation*, an *error message*, and a default *implementation* :
> {code}
> constraint-new-constraint --named URL --validatedBy URLValidator --type String
> {code}
> The constraint will now refer to the implementation class {{URLValidator.class}} :
> {code}
> @Documented
> @Constraint(validatedBy = URLValidator.class)
> @Target( { METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
> @Retention(RUNTIME)
> @ReportAsSingleViolation
> public @interface URL {
> 	String message() default "{org.mycompany.myproject.constraints.URL.message}";
> 	Class<?>[] groups() default { };
> 	Class<? extends Payload>[] payload() default { };
> 	@Target( { METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER })
> 	@Retention(RUNTIME)
> 	@Documented
> 	public @interface List {
> 		URL[] value();
> 	}
> }
> {code}
> And the default implementation will look like : 
> {code}
> public class URLValidator implements ConstraintValidator<URL, String> {
>   @Override
>   public void initialize(URL url) {
>   }
>   @Override
>   public boolean isValid(String value, ConstraintValidatorContext context) {
>     return false;
>   }
> }
> {code}

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