001// Copyright 2006, 2008, 2009, 2011 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
015package org.apache.tapestry5.internal.bindings;
016
017import org.apache.tapestry5.Binding;
018import org.apache.tapestry5.ComponentResources;
019import org.apache.tapestry5.Field;
020import org.apache.tapestry5.FieldValidator;
021import org.apache.tapestry5.commons.Location;
022import org.apache.tapestry5.commons.internal.services.StringInterner;
023import org.apache.tapestry5.commons.internal.util.TapestryException;
024import org.apache.tapestry5.services.BindingFactory;
025import 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 */
032public 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(String.format("Component '%s' is not a field (it does not implement the Field interface) and may not be used with the validate: binding prefix.", component.getCompleteId()),
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}