EntitySelector.java

/*******************************************************************************
 * Copyright (c) 2014 antoniomariasanchez at gmail.com.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Public License v3.0
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/gpl.html
 * 
 * Contributors:
 *     antoniomaria - initial API and implementation
 ******************************************************************************/
/*
 * Copyright 2012 JAXIO http://www.jaxio.com 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 net.sf.gazpachoquest.qbe;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import javax.persistence.metamodel.SingularAttribute;

import net.sf.gazpachoquest.domain.support.Persistable;

import org.apache.commons.lang3.Validate;

/**
 * Used to construct OR predicate for a single foreign key value. In other words
 * you can search all entities E having
 * their x-to-one association value set to one of the selected values. To avoid
 * a join we rely on the foreign key field,
 * not the association itself.
 */
public class EntitySelector<E, T extends Persistable, TPK extends Serializable> {

    /**
     * Import statically this helper for smooth instanciation.
     */
    static public <E2, T2 extends Persistable, TPK2 extends Serializable> EntitySelector<E2, T2, TPK2> entitySelector(
            final SingularAttribute<E2, TPK2> field) {
        return new EntitySelector<E2, T2, TPK2>(field);
    }

    static public <E2, T2 extends Persistable, TPK2 extends Serializable> EntitySelector<E2, T2, TPK2> entitySelector(
            final SingularAttribute<E2, TPK2> field, final T2... values) {
        return new EntitySelector<E2, T2, TPK2>(field, values);
    }

    /**
     * Import statically this helper for smooth instanciation. It is used in the
     * case where the PK is composite AND the
     * pk member(s) are/is also a foreign key.
     */
    static public <E2, T2 extends Persistable, TPK2 extends Serializable, CPK2> EntitySelector<E2, T2, TPK2> newEntitySelectorInCpk(
            final SingularAttribute<E2, CPK2> cpkField, final SingularAttribute<CPK2, TPK2> cpkInnerField) {
        return new EntitySelector<E2, T2, TPK2>(cpkField, cpkInnerField);
    }

    private final SingularAttribute<E, ?> cpkField;

    private final SingularAttribute<?, TPK> cpkInnerField;

    private final SingularAttribute<E, TPK> field;

    private List<T> selected = new ArrayList<T>();

    public EntitySelector(final SingularAttribute<E, ?> cpkField, final SingularAttribute<?, TPK> cpkInnerField) {
        this.cpkField = cpkField;
        this.cpkInnerField = cpkInnerField;
        this.field = null; // not used
    }

    /**
     * @param field
     *            the property holding an foreign key.
     */
    public EntitySelector(final SingularAttribute<E, TPK> field) {
        this.field = field;
        this.cpkField = null;
        this.cpkInnerField = null;
    }

    public EntitySelector(final SingularAttribute<E, TPK> field, final T... values) {
        this(field);
        for (T value : values) {
            Validate.notNull(value);
            selected.add(value);
        }
    }

    public void clearSelected() {
        if (selected != null) {
            selected.clear();
        }
    }

    public SingularAttribute<E, ?> getCpkField() {
        return cpkField;
    }

    public SingularAttribute<?, TPK> getCpkInnerField() {
        return cpkInnerField;
    }

    public SingularAttribute<E, TPK> getField() {
        return field;
    }

    /**
     * Get the possible candidates for the x-to-one association.
     */
    public List<T> getSelected() {
        return selected;
    }

    public boolean isNotEmpty() {
        return selected != null && !selected.isEmpty();
    }

    public void selected(final T... selected) {
        List<T> t = new ArrayList<T>();
        for (T s : selected) {
            t.add(s);
        }
        this.selected = t;
    }

    /**
     * Set the possible candidates for the x-to-one association.
     */
    public void setSelected(final List<T> selected) {
        this.selected = selected;
    }
}