001/*
002 *  Copyright (c) 2022-2023, Mybatis-Flex (fuhai999@gmail.com).
003 *  <p>
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *  <p>
008 *  http://www.apache.org/licenses/LICENSE-2.0
009 *  <p>
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package com.mybatisflex.core.query;
017
018
019import com.mybatisflex.core.constant.SqlConsts;
020import com.mybatisflex.core.dialect.IDialect;
021import com.mybatisflex.core.exception.FlexExceptions;
022import com.mybatisflex.core.util.ObjectUtil;
023
024import java.util.List;
025
026/**
027 * 排序字段
028 * @author michael
029 */
030public class QueryOrderBy implements CloneSupport<QueryOrderBy> {
031
032    private QueryColumn queryColumn;
033
034    /**
035     * asc, desc
036     */
037    private String orderType = SqlConsts.ASC;
038
039    private boolean nullsFirst = false;
040    private boolean nullsLast = false;
041
042    protected QueryOrderBy() {
043    }
044
045    public QueryOrderBy(QueryColumn queryColumn, String orderType) {
046        this.queryColumn = queryColumn;
047        this.orderType = orderType;
048    }
049
050
051    public QueryOrderBy(QueryColumn queryColumn) {
052        this.queryColumn = queryColumn;
053    }
054
055
056    public QueryOrderBy nullsFirst() {
057        this.nullsFirst = true;
058        this.nullsLast = false;
059        return this;
060    }
061
062
063    public QueryOrderBy nullsLast() {
064        this.nullsFirst = false;
065        this.nullsLast = true;
066        return this;
067    }
068
069
070    public String toSql(List<QueryTable> queryTables, IDialect dialect) {
071        String sql = queryColumn.toConditionSql(queryTables, dialect) + orderType;
072        if (nullsFirst) {
073            sql = sql + SqlConsts.NULLS_FIRST;
074        } else if (nullsLast) {
075            sql = sql + SqlConsts.NULLS_LAST;
076        }
077        return sql;
078    }
079
080
081    @Override
082    public QueryOrderBy clone() {
083        try {
084            QueryOrderBy clone = (QueryOrderBy) super.clone();
085            // deep clone ...
086            clone.queryColumn = ObjectUtil.clone(this.queryColumn);
087            return clone;
088        } catch (CloneNotSupportedException e) {
089            throw FlexExceptions.wrap(e);
090        }
091    }
092
093}