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    }