001    // Copyright 2007, 2008 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.tapestry.services;
016    
017    import org.apache.tapestry.Block;
018    
019    /**
020     * A source of {@link Block}s used to display the properties of a bean (used by the {@link
021     * org.apache.tapestry.corelib.components.Grid} component), or to edit the properties of a bean (used by the {@link
022     * org.apache.tapestry.corelib.components.BeanEditForm} component). Contributions to this service (a configuration of
023     * {@link BeanBlockContribution}s) define what properties may be editted.
024     * <p/>
025     * Blocks are accessed in terms of a <strong>data type</strong> a string that identifies the type of data to be editted,
026     * such as "string", "date", "boolean", etc.
027     * <p/>
028     * Tapestry contributes a number of default data types and corresponding edit and display blocks. The {@link
029     * org.apache.tapestry.services.BeanBlockOverrideSource} service allows these to be overridden.
030     *
031     * @see org.apache.tapestry.services.DataTypeAnalyzer
032     * @see org.apache.tapestry.services.TapestryModule#contributeBeanBlockSource(org.apache.tapestry.ioc.Configuration)
033     */
034    public interface BeanBlockSource
035    {
036        /**
037         * Returns a block which can be used to render an editor for the given data type, in the form of a field label and
038         * input field.
039         *
040         * @param datatype logical name for the type of data to be displayed
041         * @return the Block
042         * @throws RuntimeException if no appropriate block is available
043         */
044        Block getEditBlock(String datatype);
045    
046        /**
047         * Returns a block which can be used to render output for the given data type.
048         *
049         * @param datatype logical name for the type of data to be displayed
050         * @return the Block
051         * @throws RuntimeException if no appropriate block is available
052         */
053        Block getDisplayBlock(String datatype);
054    
055        /**
056         * Checks to see if there is a display block for the indicated data type.
057         *
058         * @param datatype to check for
059         * @return true if a block is available
060         */
061        boolean hasDisplayBlock(String datatype);
062    }