JpaViewScaffoldingStrategy.java

/**
 *
 * Copyright 2010, Lawrence McAlpin.
 *
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 */
package play.modules.scaffold.strategy;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.util.Collection;
import java.util.List;

import javax.persistence.ManyToMany;
import javax.persistence.OneToMany;
import javax.persistence.OneToOne;

import org.apache.commons.lang.StringUtils;

import play.modules.scaffold.form.FormElement;
import play.modules.scaffold.form.FormElementType;
import play.modules.scaffold.utils.Fields;

public class JpaViewScaffoldingStrategy extends DefaultViewScaffoldingStrategy {

    @Override
    public FormElement render(Field field) {
        FormElement defaultValue = super.render(field);
        if (defaultValue == null)
            return null;
        // get the list of annotations
        List<Class<? extends Annotation>> annotations = Fields.annotations(field);
        // also get the list of the names of the annotations -- this is a little
        // redundant, but the reason we do this is because different versions of
        // Play! support different versions of JPA, and we can't know at compile
        // time which classes will be available... particularly, we currently
        // support Play! 1.0 which uses JPA 1 and therefore won't have the
        // ElementCollection annotation, while Play! 1.1, which uses JPA 2,
        // does.
        List<String> annotationNames = Fields.annotationNames(field);
        if (defaultValue.getType() == FormElementType.TEXT && annotations.contains(javax.persistence.Lob.class)) {
            return new FormElement(defaultValue, FormElementType.TEXTAREA);
        }
        if (annotations.contains(javax.persistence.Id.class)) {
            return new FormElement(defaultValue, FormElementType.HIDDEN);
        } else if (annotations.contains(javax.persistence.Embedded.class)) {
            return new FormElement(defaultValue, FormElementType.EMBEDDED);
        } else if (annotations.contains(javax.persistence.OneToOne.class)) {
            OneToOne ann = field.getAnnotation(OneToOne.class);
            if (!StringUtils.isEmpty(ann.mappedBy())) {
                return null;
            }
            return new FormElement(defaultValue, FormElementType.RELATION);
        } else if (annotations.contains(javax.persistence.ManyToOne.class)) {
            return new FormElement(defaultValue, FormElementType.RELATION);
        }
        if (Collection.class.isAssignableFrom(field.getType())) {
            Class<?> parameterizedType = (Class<?>) ((ParameterizedType) field.getGenericType())
                    .getActualTypeArguments()[0];
            if (annotationNames.contains("javax.persistence.ElementCollection")
                    || annotationNames.contains("org.hibernate.annotations.CollectionOfElements")) {
                return new FormElement(defaultValue, parameterizedType, FormElementType.LIST);
            }
            if (annotations.contains(javax.persistence.OneToMany.class)) {
                OneToMany ann = field.getAnnotation(OneToMany.class);
                if (!StringUtils.isEmpty(ann.mappedBy())) {
                    return null;
                }
                return new FormElement(defaultValue, parameterizedType, FormElementType.RELATION).acceptMultiple();
            }
            if (annotations.contains(javax.persistence.ManyToMany.class)) {
                ManyToMany ann = field.getAnnotation(ManyToMany.class);
                if (!StringUtils.isEmpty(ann.mappedBy())) {
                    return null;
                }
                return new FormElement(defaultValue, parameterizedType, FormElementType.RELATION).acceptMultiple();
            }
        }
        return defaultValue;
    }
}