// Copyright (c) 2003-present, Jodd Team (http://jodd.org)
// 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.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS 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 COPYRIGHT HOLDER OR 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.
package jodd.joy.page;
import jodd.db.oom.DbOomQuery;
import jodd.db.oom.sqlgen.DbSqlBuilder;
import jodd.util.StringUtil;
import java.util.List;
import java.util.Map;
import static jodd.db.oom.DbOomQuery.query;
import static jodd.db.oom.sqlgen.DbSqlBuilder.sql;
/**
* Database pager.
*/
public abstract class DbPager {
/**
* Returns default page request when passed one is <code>null</code>.
* This usually happens on initial page view, when no page request is created.
* Returned <code>PageRequest</code> defines <i>global</i> defaults.
*/
protected PageRequest getDefaultPageRequest() {
return new PageRequest();
}
/**
* Performs the pagination with given {@link jodd.joy.page.PageRequest}.
*
* @param pageRequest page request, may be <code>null</code>, then the {@link #getDefaultPageRequest() default page request} will be used
* @param sql SQL query that lists <b>all</b> items
* @param params SQL query parameters or <code>null</code>
* @param sortColumns array of all column names
* @param target db entities for mapping (as usual in DbOom)
*
* @see #page(String, java.util.Map, int, int, String, boolean, Class[])
*/
public <T> PageData<T> page(PageRequest pageRequest, String sql, Map params, String[] sortColumns, Class[] target) {
if (pageRequest == null) {
pageRequest = getDefaultPageRequest();
}
// check sort
String sortColumName = null;
boolean ascending = true;
int sort = pageRequest.getSort();
if (sort != 0) {
ascending = sort > 0;
if (!ascending) {
sort = -sort;
}
int index = sort - 1;
if (index >= sortColumns.length) {
index = 1;
}
sortColumName = sortColumns[index];
}
// page
int page = pageRequest.getPage();
int pageSize = pageRequest.getSize();
PageData<T> pageData = page(sql, params, page, pageSize, sortColumName, ascending, target);
// fix the out-of-bounds
if (pageData.getItems().isEmpty() && pageData.currentPage != 0) {
if (pageData.currentPage != page) {
// out of bounds
int newPage = pageData.getCurrentPage();
pageData = page(sql, params, newPage, pageSize, sortColumName, ascending, target);
}
}
return pageData;
}
/**
* Pages given page.
*
* @param sql sql query that lists <b>all</b> items
* @param params map of SQL parameters
* @param page current page to show
* @param pageSize number of items to show
* @param sortColumnName name of sorting column, <code>null</code> for no sorting
* @param ascending <code>true</code> for ascending order
* @param target db entities for mapping (sa usual in DbOom)
*/
protected <T> PageData<T> page(String sql, Map params, int page, int pageSize, String sortColumnName, boolean ascending, Class[] target) {
if (sortColumnName != null) {
sql = buildOrderSql(sql, sortColumnName, ascending);
}
int from = (page - 1) * pageSize;
String pageSql = buildPageSql(sql, from, pageSize);
DbSqlBuilder dbsql = sql(pageSql);
DbOomQuery query = query(dbsql);
query.setMaxRows(pageSize);
query.setFetchSize(pageSize);
query.setMap(params);
List<T> list = query.list(pageSize, target);
query.close();
String countSql = buildCountSql(sql);
dbsql = sql(countSql);
query = query(dbsql);
query.setMap(params);
long count = query.executeCount();
query.close();
return new PageData<>(page, (int) count, pageSize, list);
}
// ---------------------------------------------------------------- abstract
/**
* Builds order SQL string.
* Invoked before all other SQL modification.
*/
protected abstract String buildOrderSql(String sql, String column, boolean ascending);
/**
* Builds page SQL string.
* Returned SQL string may return more than <code>pageSize</code> elements,
* but only <code>pageSize</code> will be consumed.
*/
protected abstract String buildPageSql(String sql, int from, int pageSize);
/**
* Builds SQL for retrieving total number of results.
*/
protected abstract String buildCountSql(String sql);
// ---------------------------------------------------------------- sql manipulation
/**
* Removes the first 'select' from the sql query.
*/
protected String removeSelect(String sql) {
int ndx = StringUtil.indexOfIgnoreCase(sql, "select");
if (ndx != -1) {
sql = sql.substring(ndx + 6); // select.length()
}
return sql;
}
/**
* Removes the first part of the sql up to the relevant 'from'.
* Tries to detect sub-queries in the 'select' part.
*/
protected String removeToFrom(String sql) {
int from = 0;
int fromCount = 1;
int selectCount = 0;
int lastNdx = 0;
while (true) {
int ndx = StringUtil.indexOfIgnoreCase(sql, "from", from);
if (ndx == -1) {
break;
}
// count selects in left part
String left = sql.substring(lastNdx, ndx);
selectCount += StringUtil.countIgnoreCase(left, "select");
if (fromCount >= selectCount) {
sql = sql.substring(ndx);
break;
}
// find next 'from'
lastNdx = ndx;
from = ndx + 4;
fromCount++;
}
return sql;
}
/**
* Removes everything from last "order by".
*/
protected String removeLastOrderBy(String sql) {
int ndx = StringUtil.lastIndexOfIgnoreCase(sql, "order by");
if (ndx != -1) {
int ndx2 = sql.lastIndexOf(sql, ')');
if (ndx > ndx2) {
sql = sql.substring(0, ndx);
}
}
return sql;
}
}