    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005//     http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.corelib.base;
    014
    015import org.apache.tapestry5.*;
    016import org.apache.tapestry5.annotations.Parameter;
    017import org.apache.tapestry5.beaneditor.PropertyModel;
    018import org.apache.tapestry5.ioc.Messages;
    019import org.apache.tapestry5.ioc.annotations.Inject;
    020import org.apache.tapestry5.ioc.internal.util.InternalUtils;
    021import org.apache.tapestry5.ioc.internal.util.TapestryException;
    022import org.apache.tapestry5.services.BeanBlockSource;
    023import org.apache.tapestry5.services.Core;
    024import org.apache.tapestry5.services.Environment;
    025import org.apache.tapestry5.services.PropertyOutputContext;
    026
    027/**
    028 * Base class for components that output a property value using a {@link PropertyModel}. There's a relationship between
    029 * such a component and its container, as the container may provide messages in its message catalog needed by the {@link
    030 * Block}s that render the values. In addition, the component may be passed Block parameters that are output overrides
    031 * for specified properties.
    032 * <p/>
    033 * Subclasses will implement a <code>beginRender()</code> method that invokes {@link #renderPropertyValue(MarkupWriter,
    034 * String)}.
    035 *
    036 * @see BeanBlockSource
    037 */
    038public abstract class AbstractPropertyOutput
    039{
    040    /**
    041     * Model for property displayed by the cell.
    042     */
    043    @Parameter(required = true, allowNull = false)
    044    private PropertyModel model;
    045
    046    /**
    047     * Used to search for block parameter overrides (this is normally the enclosing Grid component's resources).
    048     */
    049    @Parameter(required = true, allowNull = false)
    050    private PropertyOverrides overrides;
    051
    052    /**
    053     * Identifies the object being rendered. The component will extract a property from the object and render its value
    054     * (or delegate to a {@link org.apache.tapestry5.Block} that will do so).
    055     */
    056    @Parameter(required = true)
    057    private Object object;
    058
    059    /**
    060     * Source for property display blocks. This defaults to the default implementation of {@link
    061     * org.apache.tapestry5.services.BeanBlockSource}.
    062     */
    063    @Parameter(required = true, allowNull = false)
    064    private BeanBlockSource beanBlockSource;
    065
    066    @Inject
    067    @Core
    068    private BeanBlockSource defaultBeanBlockSource;
    069
    070    @Inject
    071    private Environment environment;
    072
    073    private boolean mustPopEnvironment;
    074
    075    @Inject
    076    private ComponentResources resources;
    077
    078    BeanBlockSource defaultBeanBlockSource()
    079    {
    080        return defaultBeanBlockSource;
    081    }
    082
    083    protected PropertyModel getPropertyModel()
    084    {
    085        return model;
    086    }
    087
    088    /**
    089     * Invoked from subclasses to do the rendering. The subclass controls the naming convention for locating an
    090     * overriding Block parameter (it is the name of the property possibly suffixed with a value).
    091     */
    092    protected Object renderPropertyValue(MarkupWriter writer, String overrideBlockId)
    093    {
    094        Block override = overrides.getOverrideBlock(overrideBlockId);
    095
    096        if (override != null) return override;
    097
    098        String datatype = model.getDataType();
    099
    100        if (beanBlockSource.hasDisplayBlock(datatype))
    101        {
    102            PropertyOutputContext context = new PropertyOutputContext()
    103            {
    104                public Messages getMessages()
    105                {
    106                    return overrides.getOverrideMessages();
    107                }
    108
    109                public Object getPropertyValue()
    110                {
    111                    return readPropertyForObject();
    112                }
    113
    114                public String getPropertyId()
    115                {
    116                    return model.getId();
    117                }
    118
    119                public String getPropertyName()
    120                {
    121                    return model.getPropertyName();
    122                }
    123            };
    124
    125            environment.push(PropertyOutputContext.class, context);
    126            mustPopEnvironment = true;
    127
    128            return beanBlockSource.getDisplayBlock(datatype);
    129        }
    130
    131        Object value = readPropertyForObject();
    132
    133        String text = value == null ? "" : value.toString();
    134
    135        if (InternalUtils.isNonBlank(text))
    136        {
    137            writer.write(text);
    138        }
    139
    140        // Don't render anything else
    141
    142        return false;
    143    }
    144
    145    Object readPropertyForObject()
    146    {
    147        PropertyConduit conduit = model.getConduit();
    148
    149        try
    150        {
    151            return conduit == null ? null : conduit.get(object);
    152        } catch (NullPointerException ex)
    153        {
    154            throw new TapestryException(String.format("Property '%s' contains a null value in the path.", model.getPropertyName()),
    155                    resources.getLocation(),
    156                    ex);
    157        }
    158    }
    159
    160    /**
    161     * Returns false; there's no template and this prevents the body from rendering.
    162     */
    163    boolean beforeRenderTemplate()
    164    {
    165        return false;
    166    }
    167
    168    void afterRender()
    169    {
    170        if (mustPopEnvironment)
    171        {
    172            environment.pop(PropertyOutputContext.class);
    173            mustPopEnvironment = false;
    174        }
    175    }
    176
    177    // Used for testing.
    178    void inject(final PropertyModel model, final Object object, final ComponentResources resources)
    179    {
    180        this.model = model;
    181        this.object = object;
    182        this.resources = resources;
    183    }
    184}