在myBatis< assoctiation>中传递多个列 [英] Passing multiple columns in myBatis <assoctiation>

问题描述

我想知道，我们如何在myBatis关联标签中传递多个列。

例如，我在一个mapper.xml中有以下xml片段file：

 < resultMap type =com.mysite.domain.CourseBuilderCoursesid =ResultMapWithAssmntsextends =BaseResultMap > 
 
< association property =totalAssignmentCntcolumn =course_idselect =selectTotalAssgnmentsCnt/> 
< association property =totalAssessmentCntcolumn =course_idselect =selectTotalAssesmentsCnt/> 
<！ - 查看此关联>> - > < association property =subscriptioncolumn =course_idselect =com.mysite.persistence.mybatis.CourseSubscriptionMapper.selectByUsercId/> 
 
< / resultMap> 
  

如您所见，< association> 属性订阅只有一列 course_id

我想传递2列到它，因此产生的代码，我们如何做呢？

我试过以下组合，没有工作：

  column ={course_id，user_id}// null，null作为参数传递
 column =course_id，user_id // null，null作为参数传递
 column ={COURSE_ID = course_id，USER_ID = user_id}// null，null作为参数传递
  

但如果我通过单一，
column ={course_id}或column =course_id

解决方案

没有任何问题。

>您应该为复合键使用下一个语法：

  column ={prop1 = col1，prop2 = col2}。 
  

其中 prop1，prop2 关联查询和 col1，col2 是传递给该查询的sql列。

在您的情况下：

CourseMapper.xml ：

  column ={courseId = id，userId = user_id}
 ... 
 select id，user_id，.. 。from course ... 
  

CourseSubscriptionMapper.xml ：

 < select id =selectByUsercId...> 
 select ... where course_id =＃{courseId} and user_id =＃{userId} 
< / select> 
  

我只是检查它对我来说工作得很好。
如果您有任何问题，请随时问。

I want to know, how do we pass multiple columns in a myBatis association tag.

For example, I have the following xml snippet in one my mapper.xml file:

<resultMap type="com.mysite.domain.CourseBuilderCourses" id="ResultMapWithAssmnts" extends="BaseResultMap">

    <association property="totalAssignmentCnt" column="course_id" select="selectTotalAssgnmentsCnt"/>
    <association property="totalAssessmentCnt" column="course_id" select="selectTotalAssesmentsCnt"/>  
<!--  see this association >> --> <association property="subscription" column="course_id" select="com.mysite.persistence.mybatis.CourseSubscriptionMapper.selectByUsercId"/> 

  </resultMap>

As you can see, the <association> with property subscription has only one column, course_id

I want to pass 2 columns to it, and therefore the resultant code, how do we do that?

I tried the following combinations, none worked:

column="{course_id,user_id}"   // null,null are passed as parameters 
column="course_id,user_id"   // null,null are passed as parameters 
column="{COURSE_ID=course_id,USER_ID=user_id}"   // null,null are passed as parameters 

but if I pass single, column="{course_id}" or column="course_id"

works without any issues.

Any idea guys?

解决方案

You should use next syntax for composite key:

column="{prop1=col1,prop2=col2}".

Where prop1, prop2 is parameters of the associated query and col1, col2 is sql columns passed to that query.

In your case:

CourseMapper.xml:

column="{courseId=id,userId=user_id}" 
...
select id, user_id, ... from course ...

CourseSubscriptionMapper.xml:

<select id="selectByUsercId" ...>
    select ... where course_id=#{courseId} and user_id=#{userId}
</select>

I just checked it worked fine for me. If you have any questions, please feel free to ask.

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