Problem with nested groupBy resultMaps
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Key: IBATIS-79
URL: http://issues.apache.org/jira/browse/IBATIS-79
Project: iBatis for Java
Type: Bug
Components: SQL Maps
Versions: 2.0.9b
Environment: iBATIS 2.0.9b.550
java 1.4.2_05
Mac OS X 10.3.8
MySQL 4.1.7
Reporter: Stuart Piltch
(originally posted on ibatis-user-java)
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 on the mailing list 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.
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