    001    // Copyright 2006, 2008, 2009 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.internal.bindings;
    016
    017    import org.apache.tapestry5.Binding;
    018    import org.apache.tapestry5.ComponentResources;
    019    import org.apache.tapestry5.Field;
    020    import org.apache.tapestry5.FieldValidator;
    021    import org.apache.tapestry5.internal.services.StringInterner;
    022    import org.apache.tapestry5.ioc.Location;
    023    import org.apache.tapestry5.ioc.internal.util.TapestryException;
    024    import org.apache.tapestry5.services.BindingFactory;
    025    import org.apache.tapestry5.services.FieldValidatorSource;
    026
    027    /**
    028     * Factory for bindings that provide a {@link org.apache.tapestry5.FieldValidator} based on a validator specification.
    029     * This binding factory is only useable with components that implement the {@link org.apache.tapestry5.Field}
    030     * interface.
    031     */
    032    public class ValidateBindingFactory implements BindingFactory
    033    {
    034        private final FieldValidatorSource fieldValidatorSource;
    035
    036        private final StringInterner interner;
    037
    038        public ValidateBindingFactory(FieldValidatorSource fieldValidatorSource, StringInterner interner)
    039        {
    040            this.fieldValidatorSource = fieldValidatorSource;
    041            this.interner = interner;
    042        }
    043
    044        public Binding newBinding(String description, ComponentResources container,
    045                                  ComponentResources component, final String expression, Location location)
    046        {
    047            Object fieldAsObject = component.getComponent();
    048
    049            if (!Field.class.isInstance(fieldAsObject))
    050                throw new TapestryException(BindingsMessages.validateBindingForFieldsOnly(component),
    051                                            location, null);
    052
    053            final Field field = (Field) fieldAsObject;
    054
    055            return new InvariantBinding(location, FieldValidator.class, interner.intern(description + ": " + expression))
    056            {
    057                public Object get()
    058                {
    059                    // The expression is a validator specification, such as "required,minLength=5".
    060                    // ValidatorBindingFactory is the odd man out becasuse it needs the binding component (the
    061                    // component whose parameter is to be bound) rather than the containing component, the way
    062                    // most factories work.
    063
    064                    return fieldValidatorSource.createValidators(field, expression);
    065                }
    066            };
    067        }
    068    }