    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}