项目中在使用association和collection实现一对一和一对多关系时需要对关系中结果集进行筛选，如果使用懒加载模式，即联合使用select标签时，主sql和关系映射里的sql是分开的，查询参数传递成为问题。
mybatis文档:
| property | description |
|---|---|
| column | 数据库的列名或者列标签别名。与传递给resultSet.getString(columnName)的参数名称相同。注意： 在处理组合键时，您可以使用column=“{prop1=col1,prop2=col2}”这样的语法，设置多个列名传入到嵌套查询语句。这就会把prop1和prop2设置到目标嵌套选择语句的参数对象中。 |
<resultMap id="findCountryCityAddressMap" type="map">
<result property="country" column="country"/>
<collection property="cityList"
column="{cityId=city_id,adr=addressCol, dis=districtCol}" //adr作为第二个sql查询条件key,即prop1属性
ofType="map" //addressCol即为虚拟列名
javaType="java.util.List" select="selectAddressByCityId"/>
</resultMap>
<resultMap id="selectAddressByCityIdMap" type="map">
<result property="city" column="city"/>
<collection property="addressList" column="city" ofType="map" javaType="java.util.List">
<result property="address" column="address"/>
<result property="district" column="district"/>
</collection>
</resultMap>
<select id="findCountryCityAddress" resultMap="findCountryCityAddressMap">
SELECT
ct.country,
ci.city_id,
IFNULL(#{addressQuery},'') addressCol, //为传入查询条件,构造虚拟列，虚拟列为查询条件参数值
IFNULL(#{districtQuery},'') districtCol
FROM
country ct
LEFT JOIN city ci ON ct.country_id = ci.country_id
ORDER BY ct.country_id
</select>
<select id="selectAddressByCityId" parameterType="java.util.Map" resultMap="selectAddressByCityIdMap">
SELECT
ci.city,
ads.address,
ads.district
FROM
(
SELECT
city,
city_id
FROM
city ci
WHERE
ci.city_id = #{cityId}
) ci
LEFT JOIN address ads ON ads.city_id = ci.city_id
<where>
<if test="adr!=null and adr!=''">
and ads.address RegExp #{adr}
</if>
<if test="dis!=null and dis!=''">
ads.district Regexp #{dis}
</if>
</where>
</select>
测试文件:
@Test
public void findCountryCityAddressTest() throws JsonProcessingException {
Map<String,Object> param = new HashMap<>();
param.put("addressQuery","1168");
List<Map<String, Object>> rs = countryManager.findCountryCityAddress(param);
ObjectMapper mapper = new ObjectMapper();
ObjectWriter writer = mapper.writerWithDefaultPrettyPrinter();
System.out.println(writer.writeValueAsString(rs));
}
测试结果:
[
{
"country": "Afghanistan",
"cityList": [{
"city": "Kabul",
"addressList": [{
"address": "1168 Najafabad Parkway",
"district": "Kabol"
}
]
}
],
"city_id": 251
},
{
"country": "Algeria",
"cityList": [],
"city_id": 59
}
]
可以看到，确实将查询条件通过column参数传入到第二个sql中，并执行成功
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