mybatis- 3.1.1. how to override the resultmap returned from mybatis

Question

we using mybatis 3.1.1.

we found for oracle the result map returned contains column name in Capital letters and in case of mySql the result map returned contains column name in small letters.

My question is : Is there is any way i can to write some sort of interceptor so that i can modify the result returned by result map.

Thanks.

score 4 · Accepted Answer · edited May 23 '17 at 12:03

I'm afraid the answer is that MyBatis doesn't provide any direct way to control the case of the keys in a result map. I asked this question recently on the MyBatis Google Group: https://groups.google.com/forum/?fromgroups#!topic/mybatis-user/tETs_JiugNE

The outcome is dependent on the behavior of the JBDC driver.

It also turns out that doing column aliasing as suggested by @jddsantaella doesn't work in all cases. I've tested MyBatis-3.1.1 with three databases in the past: MySQL, PostgreSQL and H2 and got different answers. With MySQL, the case of the column alias does dictate the case of the key in the hashmap. But with PostgreSQL it is always lowercase and with H2, it is always uppercase. I didn't test whether column aliases will work with Oracle, but by default it appears to return capital letters.

I see two options:

Option 1: Create some helper method that your code will always use to pull the data out of the returned map. For example:

private Object getFromMap(Map<String, Object> map, String key) {
  if (map.containsKey(key.toLowerCase())) {
    return map.get(key.toLowerCase());
  } else {
    return map.get(key.toUpperCase());
  }
}

Option 2: Write a LowerCaseMap class that extends from java.util.AbstractMap or java.util.HashMap and wrappers all calls to put, putAll and/or get to always be lower case. Then specify that MyBatis should use your specific LowerCaseMap rather than a standard HashMap, when populating the data from the query.

If you like this idea and want help on how to tell MyBatis how to use a different concrete collection class, see my answer to this StackOverflow question: https://stackoverflow.com/a/11596014/871012

I was thinking that there could be some way i can change the code of API but finally i have opted for second option. — Zuned Ahmed, Aug 03 '12 at 01:44

score 0 · Answer 2 · answered Jul 30 '12 at 11:49

0

What if you modify the query so you get the exactly column name you need? For example:

select my_column as MY_COLUMN from ...

answered Jul 30 '12 at 11:49

jddsantaella

3,657
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it will be real tedious task to manually modify for each and every query. There are lots select query fired from mybatis. Is there is any way i can do it with some interceptor? – Zuned Ahmed Jul 30 '12 at 11:58
i want to be it in lower case but in oracle it is always coming out to be in caps – Zuned Ahmed Jul 30 '12 at 12:11

score 0 · Answer 3 · edited Aug 05 '20 at 07:35

0

The idea of a LowerCaseMap as the ResultType is sound, but you can probably avoid writing your own. In my case I'm using org.apache.commons.collections4.map.CaseInsensitiveMap:

<select id="getTableValues" 
        resultType="org.apache.commons.collections.map.CaseInsensitiveMap">
      SELECT *
        FROM my_table
       WHERE seq_val=#{seq_val}
</select>

edited Aug 05 '20 at 07:35

Community

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answered Feb 13 '13 at 19:31

pmorken

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mybatis- 3.1.1. how to override the resultmap returned from mybatis

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