There is no getter for property named 'expertGoodAtId' in 'class java.lang.Long'

問題：用mybatis查詢時傳入一個Long參數且進行判斷時報:There is no getter for property named 'expertGoodAtId' in 'class java.lang.Long'

原始xml檔案：

<pre name="code" class="html"><!-- App專家接口查詢：根據搜尋條件查詢，按專家id分組，按專家分數倒叙排序 -->
	<select id="expertByScoreOrderQuery"  parameterType="java.lang.Long" resultType="java.util.Map">
		select ex.id,ex.expert_name AS expertName,ex.phone,ex.header_url AS headerUrl,ex.longitude,ex.latitude,ee.score,
                GROUP_CONCAT(vm.models_name)AS expertGoodAt
		from ykat_expert ex
		LEFT JOIN ykat_expert_evaluate ee ON ex.id=ee.expert_id
		LEFT JOIN ykat_expert_models em ON ee.expert_id=em.expert_id
		LEFT JOIN ykat_vehicle_models vm ON em.vehicle_models_id=vm.id
		where 1=1 and ex.is_del=1
		<if test="expertGoodAtId!=null and expertGoodAtId!='' ">
			and vm.id=#{expertGoodAtId}
		</if>
		GROUP BY ex.id
		ORDER BY ee.score desc
	</select>
           

解決方法：

方法一：無論什麼參數均使用“_parameter”

<!-- App專家接口查詢：根據搜尋條件查詢，按專家id分組，按專家分數倒叙排序 -->
	<select id="expertByScoreOrderQuery"  parameterType="java.lang.Long" resultType="java.util.Map">
		select ex.id,ex.expert_name AS expertName,ex.phone,ex.header_url AS headerUrl,ex.longitude,ex.latitude,ee.score,
                GROUP_CONCAT(vm.models_name)AS expertGoodAt
		from ykat_expert ex
		LEFT JOIN ykat_expert_evaluate ee ON ex.id=ee.expert_id
		LEFT JOIN ykat_expert_models em ON ee.expert_id=em.expert_id
		LEFT JOIN ykat_vehicle_models vm ON em.vehicle_models_id=vm.id
		where 1=1 and ex.is_del=1
		<if test="_parameter!=null and _parameter!='' ">
			and vm.id=#{expertGoodAtId}
		</if>
		GROUP BY ex.id
		ORDER BY ee.score desc
	</select>
           

方法二：dao接口參數添加注釋，說明是對應哪個參數名（實際開發中常用方法）

/**
     * @descript:App查詢專家：根據查詢條件，按專家分數倒叙排序
     * @param expertGoodAtId 專家擅長車輛id
     * @return
     */
     List<Map<String, Object>> expertByScoreOrderQuery(@Param(value="expertGoodAtId")Long expertGoodAtId);
           

原因分析

Mybatis預設采用ONGL解析參數，是以會自動采用對象樹的形式取long.num值引起報錯

備注：

1：mybaties中注解value可以省略不寫如@Param("expertGoodAtId")與@Param(value="expertGoodAtId")是一個意思

2： GROUP_CONCAT(vm.models_name)是mysql對查詢2條相同資料合并成一行顯示，并且必須根據某個字段分組，統計時使用distinct排除重複資料