9.20 mybatis的ResultMap和ResultType

[vieyahn2017]

使用resultType进行输出映射，只有查询出来的列名和pojo中的属性名一致，该列才可以映射成功。

如果查询出来的列名和pojo的属性名不一致，通过定义一个resultMap对列名和pojo属性名之间作一个映射关系。

[vieyahn2017]

Mybatis：resultMap的使用总结
https://www.cnblogs.com/kenhome/p/7764398.html

[vieyahn2017]

关联的嵌套查询（在collection中添加select属性）：

商品结果集映射resultMap：

<resultMap id="BasePlusResultMap" type="com.meikai.shop.entity.TShopSku">
    <id column="ID" jdbcType="BIGINT" property="id" />
    <result column="SKU_NAME" jdbcType="VARCHAR" property="skuName" />
    <result column="CATEGORY_ID" jdbcType="BIGINT" property="categoryId" />
    <collection column="{skuId=ID}" property="attributes" ofType="com.meikai.shop.entity.TShopAttribute" select="getAttribute" > 
    </collection>
</resultMap>

collection的select会执行下面的查询属性语句：

<select id="getAttribute"  resultMap="AttributeResultMap">
    select a.ID,s.ATTRIBUTE_NAME
    from t_shop_attribute a
    where  a.ID = #{skuId,jdbcType =BIGINT};
</select>

属性结果集映射：

<resultMap id="AttributeResultMap" type="com.meikai.shop.entity.TShopAttribute">
    <id column="ID" jdbcType="BIGINT" property="id" />
    <result column="ATTRIBUTE_NAME" jdbcType="VARCHAR" property="attributeName" />
</resultMap>

BasePlusResultMap包含了属性查询语句的Collection

所以通过下面的查询商品语句就可获得商品以及其包含的属性集合：

<select id="getById"  resultMap="BasePlusResultMap">
    select s.ID,s.SKU_NAME,s.CATEGORY_ID
    from t_shop_sku s
    where  s.ID = #{id,jdbcType =BIGINT};
</select>

[vieyahn2017]

11.2 写的一个工具
transResultMap.py

#!/usr/bin/env python
# -*- coding:utf-8 -*-

import re

lines = """
//从java类自动生成mapper.xml的resultMap映射行

public class ABCDS
{
    private String node;

    private String name;

    @Column(name = "first_key")
    private String firstKey;

    @Column(name = "second_key")
    private String secondKey;

    private List links;

    private int num = 0;

}

    <resultMap id="ABCDSMap"
               type="com....ABCDS">
        <result column="node" jdbcType="VARCHAR" property="node"/>
        <result column="name" jdbcType="VARCHAR" property="name"/>
        <result column="first_key" jdbcType="VARCHAR" property="firstKey"/>
        <result column="second_key" jdbcType="VARCHAR" property="secondKey"/>
    </resultMap>

"""


def get_column_name_line(items, pos):
    #最多只倒着往上查五行
    for i in range(5):
        if(len(items[pos-i]) < 3):
            return -1
        if "Column" in items[pos-i]:
            return pos-i
    return -1

def get_column_name_by_line(items, pos):
    # result = re.search("@Column\(name\s+=\s+(\w+)", '@Column(name = "second_key")'.replace('"', ''))
    line = get_column_name_line(items, pos)
    if line != -1:
        pattern = "@Column\(name\s+=\s+(\w+)"
        result = re.search(pattern, items[line].replace('"', ''))
        if result: 
            return result.groups()[0]


def make_result_columns(lines, is_log=True):
    items = lines.split('\n')
    results = []
    # i = 0

    for i, item in enumerate(items):
        if "private" in item:
            pattern = "private\s+(\w+)\s+(\w+)"
            # result = re.search("private\s+(\w+)\s+(\w+)", 'private List links;')
            result = re.search(pattern, item)
            if result: 
                key = result.groups()[1]
                column = get_column_name_by_line(items, i)
                if column:
                    results.append('<result column="{0}" jdbcType="VARCHAR" property="{1}"/>'.format(column, key))
                else:
                    results.append('<result column="{0}" jdbcType="VARCHAR" property="{1}"/>'.format(key, key))
    if is_log:
        print "\n".join(results)
    return "\n".join(results)


if __name__ == "__main__":
    make_result_columns(lines)

运行情况：

python transResultMap.py
<result column="node" jdbcType="VARCHAR" property="node"/>
<result column="name" jdbcType="VARCHAR" property="name"/>
<result column="first_key" jdbcType="VARCHAR" property="firstKey"/>
<result column="second_key" jdbcType="VARCHAR" property="secondKey"/>
<result column="links" jdbcType="VARCHAR" property="links"/>
<result column="num" jdbcType="VARCHAR" property="num"/>