    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 *
    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     * @param writer a MarkupWriter
    092     * @param overrideBlockId the override block id
    093     * @return a Block
    094     */
    095    protected Object renderPropertyValue(MarkupWriter writer, String overrideBlockId)
    096    {
    097        Block override = overrides.getOverrideBlock(overrideBlockId);
    098
    099        if (override != null) return override;
    100
    101        String datatype = model.getDataType();
    102
    103        if (beanBlockSource.hasDisplayBlock(datatype))
    104        {
    105            PropertyOutputContext context = new PropertyOutputContext()
    106            {
    107                public Messages getMessages()
    108                {
    109                    return overrides.getOverrideMessages();
    110                }
    111
    112                public Object getPropertyValue()
    113                {
    114                    return readPropertyForObject();
    115                }
    116
    117                public String getPropertyId()
    118                {
    119                    return model.getId();
    120                }
    121
    122                public String getPropertyName()
    123                {
    124                    return model.getPropertyName();
    125                }
    126            };
    127
    128            environment.push(PropertyOutputContext.class, context);
    129            mustPopEnvironment = true;
    130
    131            return beanBlockSource.getDisplayBlock(datatype);
    132        }
    133
    134        Object value = readPropertyForObject();
    135
    136        String text = value == null ? "" : value.toString();
    137
    138        if (InternalUtils.isNonBlank(text))
    139        {
    140            writer.write(text);
    141        }
    142
    143        // Don't render anything else
    144
    145        return false;
    146    }
    147
    148    Object readPropertyForObject()
    149    {
    150        PropertyConduit conduit = model.getConduit();
    151
    152        try
    153        {
    154            return conduit == null ? null : conduit.get(object);
    155        } catch (NullPointerException ex)
    156        {
    157            throw new TapestryException(String.format("Property '%s' contains a null value in the path.", model.getPropertyName()),
    158                    resources.getLocation(),
    159                    ex);
    160        }
    161    }
    162
    163    /**
    164     * Returns false; there's no template and this prevents the body from rendering.
    165     */
    166    boolean beforeRenderTemplate()
    167    {
    168        return false;
    169    }
    170
    171    void afterRender()
    172    {
    173        if (mustPopEnvironment)
    174        {
    175            environment.pop(PropertyOutputContext.class);
    176            mustPopEnvironment = false;
    177        }
    178    }
    179
    180    // Used for testing.
    181    void inject(final PropertyModel model, final Object object, final ComponentResources resources)
    182    {
    183        this.model = model;
    184        this.object = object;
    185        this.resources = resources;
    186    }
    187}