詳解mybatis中association和collection的column傳入多個參數問題

這篇文章主要介紹了詳解mybatis中association和collection的column傳入多個參數問題，文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值，需要的朋友們下面隨着小編來一起學習學習吧

項目中在使用association和collection實現一對一和一對多關係時需要對關係中結果集進行篩選，如果使用懶加載模式，即聯合使用select標籤時，主sql和關係映射裏的sql是分開的，查詢參數傳遞成爲問題。

mybatis文檔:

property	description
column	數據庫的列名或者列標籤別名。與傳遞給resultSet.getString(columnName)的參數名稱相同。注意： 在處理組合鍵時，您可以使用column=“{prop1=col1,prop2=col2}”這樣的語法，設置多個列名傳入到嵌套查詢語句。這就會把prop1和prop2設置到目標嵌套選擇語句的參數對象中。

<resultMap id="findCountryCityAddressMap" type="map">
 <result property="country" column="country"/>
 <collection property="cityList"
    column="{cityId=city_id,adr=addressCol, dis=districtCol}" //adr作爲第二個sql查詢條件key,即prop1屬性
    ofType="map"            //addressCol即爲虛擬列名
    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, //爲傳入查詢條件,構造虛擬列，虛擬列爲查詢條件參數值
  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>

測試文件:

@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));
}

測試結果:

[
 {
  "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，確實將查詢條件通過column參數傳入到第二個sql中，並執行成功

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