Java ->在mybatis和PostgreSQL Json字段作为查询条件的解决方案

读前思考：

　　你没想到解决办法？PostgreSQL 数据库本身就支持还是另有解决办法？

使用JOSNB作为字段类型。现在开始,,,,,,,,,,,,,,,,,,

json如下：

"rule":{
    "tags": {
        "target": "logon"
    },
    "time": "2019-11-15 10:00:00",
    "method": "scheduled",
    "source": "backend",
    "aliases": [],
    "sendType": "tag",
    "registrationIds": []
}

现在我想获取 rule 字段 里面的  sendType="tag",那现在怎么搞？

代码如下：

  #####Mybatis#####
  <select id="selectPushDataList" resultMap="BaseResultMap" parameterType="com.jpc.JpushData" >
    SELECT
      <include refid="Base_Column_List" />
    FROM
        jp_push jpt
    <where>
      delete_flag=1
      and (rule::json->>'sendType')::text = 'tag'
      <if test="name != null and name !=''" >
        and name =#{name,jdbcType=VARCHAR}
      </if>
      ORDER BY
        create_time ASC
         LIMIT ${pageSize} OFFSET ${(currentPage - 1) * pageSize}
    </where>
  </select>
 
  ####PostgreSQL  SQL####
      SELECT
        uuid,create_user,create_time,update_user,update_time,delete_flag,NAME,type,push,rule, STATUS
    FROM
        jp_push jpt
    WHERE
        jpt.delete_flag = 1
        AND ( jpct.rule :: json ->> 'sendType' ) :: text = 'tag'
        AND jpt.NAME = 'testname'
    ORDER BY jpt.create_time ASC LIMIT 20 OFFSET 0

结果如下：

再看如下的json串：

--如何获取title，description呢--------

----------pre- zh en app----------
"pre": {
  "zh": {
     "app": {
       "title": "test",
       "description": "test",
       "images": [
           "https://www.baidu.com/",
           "https://www.baidu.com/1"
   ]
}
},
"en": {
 "app": {
  "title": "test",
   "description": "test",
   "images": [
    "https://www.baidu.com/",
   "https://www.baidu.com/1"
  ]
  }
}
---------------pre zh en web------------------------------------
"pre": {
  "zh": {
   "web": {
   "title": "test",
   "description": "test",
    "images": [
      "https://www.baidu.com/",
      "https://www.baidu.com/1"
   ]
  }
},
"en": {
"web": {
  "title": "test",
  "description": "test",
     "images": [
       "https://www.baidu.com/",
       "https://www.baidu.com/1"
    ]
   }
  }
}

如何写sql？ 把语言和端作为一个变量传进去...

SELECT
　　　　uuid,　address,pre,
　　　　pre :: json -> '${lunguage}' -> '${device}' ->> 'title' AS title,
　　　　pre :: json -> '${lunguage}' -> '${device}' ->> 'description' AS description
FROM
　　"ban".test j

获取 zh-web不为空的内容：

lunguage 传  zh,device传 web

SELECT
　　　　uuid,address,　pre,
　　　　pre :: json -> '${lunguage}' -> '${device}' ->> 'title' AS title,
　　　　pre :: json -> '${lunguage}' -> '${device}' ->> 'description' AS description
FROM
　　"ban".test j  where  pre :: json -> '${lunguage}' -> '${device}' is not null

获取 zh-web-images数组里面的第一个图片信息不为空的内容：

SELECT 
     uuid,address,　pre,
　　　　pre :: json -> '${lunguage}' -> '${device}' ->> 'title' AS title,
　　　　pre :: json -> '${lunguage}' -> '${device}' ->> 'description' AS description,
       pre :: json -> '${lunguage}' -> '${device}' ->>0::'images' AS images
FROM 
   　"ban".test j where pre :: json -> '${lunguage}' -> '${device}' is not null

总结：PostgreSQL 本身就支持以json作为sql的查询条件。