001/*
002 *  Copyright (c) 2022-2025, 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 */
016
017package com.mybatisflex.core.activerecord.query;
018
019import com.mybatisflex.core.activerecord.Model;
020import com.mybatisflex.core.field.FieldQueryManager;
021import com.mybatisflex.core.field.QueryBuilder;
022import com.mybatisflex.core.mybatis.MappedStatementTypes;
023import com.mybatisflex.core.query.FieldsBuilder;
024import com.mybatisflex.core.util.LambdaGetter;
025
026import java.io.Serializable;
027import java.util.Collections;
028import java.util.List;
029
030/**
031 * 使用 {@code Fields Query} 的方式进行关联查询。
032 *
033 * @author 王帅
034 * @since 2023-07-30
035 */
036public class FieldsQuery<T extends Model<T>> extends FieldsBuilder<T> {
037
038    public FieldsQuery(Model<T> model) {
039        super(model);
040    }
041
042    @Override
043    public <F> FieldsQuery<T> fieldMapping(LambdaGetter<F> field, QueryBuilder<F> builder) {
044        super.fieldMapping(field, builder);
045        return this;
046    }
047
048    @Override
049    public <F> FieldsBuilder<T> fieldMapping(LambdaGetter<F> field, boolean prevent, QueryBuilder<F> builder) {
050        super.fieldMapping(field, prevent, builder);
051        return this;
052    }
053
054    protected Object pkValue() {
055        // 懒加载，实际用到的时候才会生成 主键值
056        return ((Model<T>) delegate).pkValue();
057    }
058
059    /**
060     * 根据主键查询一条数据。
061     *
062     * @return 一条数据
063     */
064    public T oneById() {
065        List<T> entities = Collections.singletonList(baseMapper().selectOneById((Serializable) pkValue()));
066        FieldQueryManager.queryFields(baseMapper(), entities, fieldQueryMap);
067        return entities.get(0);
068    }
069
070    /**
071     * 根据主键查询一条数据，返回的数据为 asType 类型。
072     *
073     * @param asType 接收数据类型
074     * @param <R>    接收数据类型
075     * @return 一条数据
076     */
077    @SuppressWarnings("unchecked")
078    public <R> R oneByIdAs(Class<R> asType) {
079        try {
080            MappedStatementTypes.setCurrentType(asType);
081            List<R> entities = Collections.singletonList((R) baseMapper().selectOneById((Serializable) pkValue()));
082            FieldQueryManager.queryFields(baseMapper(), entities, fieldQueryMap);
083            return entities.get(0);
084        } finally {
085            MappedStatementTypes.clear();
086        }
087    }
088
089}