Hi there,
I've been working on a query that involves two levels of groupBy, similar to the
JPetStore-ish example from the UnitTests that Clinton posted here a while ago
(http://article.gmane.org/gmane.comp.java.ibatisdb.user/383).
It was working most of the time, but would fail under certain cirumstances.
After way too many dead-ends, I found out that if the groupBy from the first
resultMap has the same value as the groupBy from the second resultMap, iBATIS
gets a bit confused and tries to assign the second result to a property from the
first class. Since that makes almost no sense now that I see it in print, let me
copy/paste some examples. The goal is a report that shows "topics" as rows
(grouped into categories), with "months" as columns and the total topics
displayed per month in the table itself.
<resultMap id="reportResult" class="Category" groupBy="categoryName">
<result property="categoryName" column="topic_category_name" />
<result property="topics" resultMap="Report.topicResult" />
</resultMap>
<resultMap id="topicResult" class="Topic" groupBy="topicName">
<result property="topicName" column="topic_name" />
<result property="months" resultMap="Report.monthResult" />
</resultMap>
<resultMap id="monthResult" class="Month">
<result property="monthName" column="month_name" />
<result property="count" column="count" />
</resultMap>
<select id="getTopicsByMonth" parameterClass="Report"
resultMap="reportResult">
SELECT tc.topic_category_name,
t.topic_name,
CONCAT(MONTHNAME(td.display_date), ' ', YEAR(td.display_date)) AS
'month_name',
COUNT(td.topics_displayed_id) AS 'count'
FROM topic t,
topic_category tc,
topics_displayed td
WHERE t.topic_id = td.topic_id
AND t.topic_category_id = tc.topic_category_id
AND td.display_date >= #startDate#
AND td.display_date <= #endDate#
GROUP BY 'category', 'row', 'column'
ORDER BY tc.sort_order,t.sort_order, YEAR(td.display_date),
MONTH(td.display_date)
</select>
Now, everything works perfectly *except* when the topic_category_name happens to
equal the topic_name. In that case, iBATIS fails with:
com.ibatis.common.beans.ProbeException: There is no READABLE property named
'months' in class '[...snip...].Category'
at com.ibatis.common.beans.ClassInfo.getGetter(ClassInfo.java:160)
at com.ibatis.common.beans.JavaBeanProbe.getProperty(JavaBeanProbe.java:263)
at com.ibatis.common.beans.JavaBeanProbe.getObject(JavaBeanProbe.java:252)
at com.ibatis.common.beans.GenericProbe.getObject(GenericProbe.java:55)
at com.ibatis.sqlmap.engine.mapping.result.BasicResultMap.
setNestedResultMappingValue(BasicResultMap.java:334)
[...let me know if you really want to see the rest...]
So, for some reason, when iBATIS is reading the months counts for this
particular topic, it tries to save the months in Category instead of in Topic.
As soon as I changed the one topic_name in the database, everything worked fine.
>From a quick step-through of the code, my first guess is that the problem is
with the single uniqueKeys map per request (used in the
BasicResultMap.setResultObjectValues() method). Can someone verify this? Should
this type of message go in jira instead of here?
I'm using the latest build (2.0.9b.550)
Cheers,
- stuart
ps. I wanted to say thanks to Clinton and the development team! I've been using
iBATIS for almost two years and it's great to see the community
growing (not to mention the features of the framework itself).
