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 */
016package com.mybatisflex.core.field;
017
018import com.mybatisflex.core.exception.FlexAssert;
019import com.mybatisflex.core.util.LambdaGetter;
020import com.mybatisflex.core.util.LambdaUtil;
021
022import java.io.Serializable;
023
024/**
025 * 属性查询构建者。
026 *
027 * @param <T> 属性所在实体类类型
028 * @author 开源海哥
029 * @author 王帅
030 */
031public class FieldQueryBuilder<T> implements Serializable {
032
033    private FieldQuery.Builder<?> builder;
034
035    /**
036     * 为指定属性创建查询。
037     *
038     * @param fn Lambda 引用
039     * @return {@link FieldQuery.Builder} 构建者
040     */
041    public FieldQuery.Builder<T> field(LambdaGetter<T> fn) {
042        return createBuilder(fn);
043    }
044
045    /**
046     * 为指定嵌套属性创建查询。
047     *
048     * @param <N> 嵌套属性类型
049     * @param fn  Lambda 引用
050     * @return {@link FieldQuery.Builder} 构建者
051     */
052    public <N> FieldQuery.Builder<N> nestedField(LambdaGetter<N> fn) {
053        return createBuilder(fn);
054    }
055
056    /**
057     * <p>创建 {@link FieldQuery.Builder} 用于构建属性类型与 {@code QueryWrapper} 用于查询。
058     *
059     * <p>该方法主要用作于创建构建者对象，以及泛型的转换。
060     */
061    @SuppressWarnings({"rawtypes", "unchecked"})
062    private <R> FieldQuery.Builder<R> createBuilder(LambdaGetter fn) {
063        FlexAssert.notNull(fn, "Field can not be null.");
064        Class<?> entityClass = LambdaUtil.getImplClass(fn);
065        String fieldName = LambdaUtil.getFieldName(fn);
066        builder = new FieldQuery.Builder<>(entityClass, fieldName);
067        return (FieldQuery.Builder<R>) builder;
068    }
069
070    public FieldQuery build() {
071        return builder.build();
072    }
073
074}