在日常開發中,查詢資料傳回類型為map,資料庫中有些自動值為空,則傳回的結果中沒有值為空的字段,則如何顯示值為空的字段呢?
1.xml檔案:
<resultMap id="userLoginInfo" type="map" >
<result column="uuid" property="id" />
<result column="uuid2" property="uuid" />
<result column="account" property="phone" />
<result column="login_time" property="loginTime" />
<result column="token" property="token" />
<result column="data_progress" property="dataProgress" />
<result column="account_locked" property="accountLocked" />
<result column="is_delete" property="isDelete" />
<result column="nickname" property="nickname" />
<result column="user_head" property="userHead" />
</resultMap>
傳回結果:
{accountLocked=false, loginTime=1480559610977, phone=18301413850, isDelete=false, dataProgress=0, nickname=,
id=93cd68fcb95043febd28d6ad86666029, uuid=544dc45953e2dcc60e23ecccc52c578b, token=WT1Kgx}
發現傳回結果Map中沒有user_head字段,原來 user_head在資料庫中值為null,是以說資料庫中所有值為null的字段在查詢接收resultMap時都不存在
解決方法:
1、在Mybatis_config.xml檔案中添加配置資訊:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<!--解決,查詢傳回結果含null沒有對應字段值問題-->
<setting name="callSettersOnNulls" value="true"/>
</settings>
</configuration>
備注:注意xml檔案的頭部引入的是mybaties-3-config.dtd
測試結果:
{accountLocked=false, loginTime=1480559610977, userHead=null, phone=18301413850, isDelete=false, dataProgress=0, nickname=,
id=93cd68fcb95043febd28d6ad86666029, uuid=544dc45953e2dcc60e23ecccc52c578b, token=WT1Kgx}
經測試,值為null的結果在map中存在