001    // Copyright 2007, 2008 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.services;
016    
017    import org.apache.tapestry5.FieldValidator;
018    import org.apache.tapestry5.ioc.AnnotationProvider;
019    import org.apache.tapestry5.ioc.annotations.UsesOrderedConfiguration;
020    
021    import java.util.List;
022    
023    /**
024     * Invoked to generate a list of validation constraint strings for a property. This typically involves scanning the
025     * property for annotations or naming conventions that confer the desired validation. The constraint strings are
026     * ultimately handed to {@link FieldValidatorSource#createValidator(org.apache.tapestry5.Field, String, String, String,
027     * org.apache.tapestry5.ioc.Messages, java.util.Locale)}.
028     */
029    @UsesOrderedConfiguration(ValidationConstraintGenerator.class)
030    public interface ValidationConstraintGenerator
031    {
032        /**
033         * For a given property, identify all the approprite validation constraints. Each returned value is the name of a
034         * validator (i.e., "required") or a validator name and configuration (i.e., "minlength=5"). These contraints are
035         * exactly the individual terms in a {@link FieldValidatorSource#createValidators(org.apache.tapestry5.Field,
036         * String) validate specification}. These will ultimately be used to create {@link FieldValidator}s for the field
037         * that edits the property.
038         *
039         * @param propertyType       the type of the property for which constraints are needed
040         * @param annotationProvider provides access to any annotations concerning the property (for implementations that
041         *                           are based on analysis of property annotations)
042         * @return a list of constraints
043         * @see FieldValidatorSource
044         */
045        List<String> buildConstraints(Class propertyType, AnnotationProvider annotationProvider);
046    }