org.objectstyle.cayenne.access.trans.QueryAssembler Maven / Gradle / Ivy

Go to download
/* ====================================================================
 * 
 * The ObjectStyle Group Software License, version 1.1
 * ObjectStyle Group - http://objectstyle.org/
 * 
 * Copyright (c) 2002-2005, Andrei (Andrus) Adamchik and individual authors
 * of the software. All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 
 * 3. The end-user documentation included with the redistribution, if any,
 *    must include the following acknowlegement:
 *    "This product includes software developed by independent contributors
 *    and hosted on ObjectStyle Group web site (http://objectstyle.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 * 
 * 4. The names "ObjectStyle Group" and "Cayenne" must not be used to endorse
 *    or promote products derived from this software without prior written
 *    permission. For written permission, email
 *    "andrus at objectstyle dot org".
 * 
 * 5. Products derived from this software may not be called "ObjectStyle"
 *    or "Cayenne", nor may "ObjectStyle" or "Cayenne" appear in their
 *    names without prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE OBJECTSTYLE GROUP OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 * 
 * This software consists of voluntary contributions made by many
 * individuals and hosted on ObjectStyle Group web site.  For more
 * information on the ObjectStyle Group, please see
 * .
 */
package org.objectstyle.cayenne.access.trans;

import java.sql.PreparedStatement;
import java.util.ArrayList;
import java.util.List;

import org.objectstyle.cayenne.access.QueryLogger;
import org.objectstyle.cayenne.access.QueryTranslator;
import org.objectstyle.cayenne.map.DbAttribute;
import org.objectstyle.cayenne.map.DbEntity;
import org.objectstyle.cayenne.map.DbRelationship;

/**
 * Abstract superclass of Query translators.
 * 
 * @author Andrei Adamchik
 */
public abstract class QueryAssembler extends QueryTranslator {

    /** PreparedStatement values. */
    protected List values = new ArrayList();

    /**
     * PreparedStatement attributes matching entries in values list.
     */
    protected List attributes = new ArrayList();

    /** Processes a join being added. */
    public abstract void dbRelationshipAdded(DbRelationship dbRel);

    /**
     * Translates query into sql string. This is a workhorse method of QueryAssembler. It
     * is called internally from createStatement. Usually there is no need
     * to invoke it explicitly.
     */
    public abstract String createSqlString() throws Exception;

    public String aliasForTable(DbEntity ent, DbRelationship rel) {
        return aliasForTable(ent); // Default implementation
    }

    /**
     * Returns a name that can be used as column alias. This can be one of the following:
     * 
     * an alias for this table, if it uses aliases
     * a fully qualified table name, if not.
     * 
     * CayenneRuntimeException is thrown if a table alias can not be created.
     */
    public abstract String aliasForTable(DbEntity dbEnt);

    /**
     * Returns true if table aliases are supported. Default implementation
     * returns false.
     */
    public boolean supportsTableAliases() {
        return false;
    }

    /**
     * Registers anObject as a PreparedStatement paramter.
     * 
     * @param anObject object that represents a value of DbAttribute
     * @param dbAttr DbAttribute being processed.
     */
    public void addToParamList(DbAttribute dbAttr, Object anObject) {
        attributes.add(dbAttr);
        values.add(anObject);
    }

    /** 
     * Translates internal query into PreparedStatement. 
     */
    public PreparedStatement createStatement() throws Exception {
        long t1 = System.currentTimeMillis();
        String sqlStr = createSqlString();
        QueryLogger.logQuery(sqlStr, values, System.currentTimeMillis() - t1);
        PreparedStatement stmt = connection.prepareStatement(sqlStr);
        initStatement(stmt);
        return stmt;
    }

    /**
     * Initializes prepared statements with collected parameters. Called internally from
     * "createStatement". Cayenne users shouldn't normally call it directly.
     */
    protected void initStatement(PreparedStatement stmt) throws Exception {
        if (values != null && values.size() > 0) {
            int len = values.size();
            for (int i = 0; i < len; i++) {
                Object val = values.get(i);

                DbAttribute attr = (DbAttribute) attributes.get(i);

                // null DbAttributes are a result of inferior qualifier processing
                // (qualifier can't map parameters to DbAttributes and therefore
                // only supports standard java types now)
                // hence, a special moronic case here:
                if (attr == null) {
                    stmt.setObject(i + 1, val);
                }
                else {
                    int type = attr.getType();
                    int precision = attr.getPrecision();
                    adapter.bindParameter(stmt, val, i + 1, type, precision);
                }
            }
        }
    }
}