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詳解mybatis中association和collection的column傳入多個(gè)參數(shù)問(wèn)題

更新時(shí)間：2019年10月02日 11:30:07 作者：iiaythi

這篇文章主要介紹了詳解mybatis中association和collection的column傳入多個(gè)參數(shù)問(wèn)題，文中通過(guò)示例代碼介紹的非常詳細(xì)，對(duì)大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價(jià)值，需要的朋友們下面隨著小編來(lái)一起學(xué)習(xí)學(xué)習(xí)吧

項(xiàng)目中在使用association和collection實(shí)現(xiàn)一對(duì)一和一對(duì)多關(guān)系時(shí)需要對(duì)關(guān)系中結(jié)果集進(jìn)行篩選，如果使用懶加載模式，即聯(lián)合使用select標(biāo)簽時(shí)，主sql和關(guān)系映射里的sql是分開(kāi)的，查詢參數(shù)傳遞成為問(wèn)題。

mybatis文檔:

property	description
column	數(shù)據(jù)庫(kù)的列名或者列標(biāo)簽別名。與傳遞給resultSet.getString(columnName)的參數(shù)名稱相同。注意：在處理組合鍵時(shí)，您可以使用column=“{prop1=col1,prop2=col2}”這樣的語(yǔ)法，設(shè)置多個(gè)列名傳入到嵌套查詢語(yǔ)句。這就會(huì)把prop1和prop2設(shè)置到目標(biāo)嵌套選擇語(yǔ)句的參數(shù)對(duì)象中。

property

description

column

數(shù)據(jù)庫(kù)的列名或者列標(biāo)簽別名。與傳遞給resultSet.getString(columnName)的參數(shù)名稱相同。注意：在處理組合鍵時(shí)，您可以使用column=“{prop1=col1,prop2=col2}”這樣的語(yǔ)法，設(shè)置多個(gè)列名傳入到嵌套查詢語(yǔ)句。這就會(huì)把prop1和prop2設(shè)置到目標(biāo)嵌套選擇語(yǔ)句的參數(shù)對(duì)象中。

<resultMap id="findCountryCityAddressMap" type="map">
 <result property="country" column="country"/>
 <collection property="cityList"
    column="{cityId=city_id,adr=addressCol, dis=districtCol}" //adr作為第二個(gè)sql查詢條件key,即prop1屬性
    ofType="map"            //addressCol即為虛擬列名
    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, //為傳入查詢條件,構(gòu)造虛擬列，虛擬列為查詢條件參數(shù)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(cè)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(cè)試結(jié)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(shí)將查詢條件通過(guò)column參數(shù)傳入到第二個(gè)sql中，并執(zhí)行成功

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