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From "Thomas G. Schuessler" <...@arasoft.de>
Subject iBATIS 3.0 selectOne SessionException if no data found
Date Wed, 26 Aug 2009 15:21:57 GMT

>In my MySQL db, I have a table 'users' with (amongst others) these fields:
>
>   `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
>   `email` varchar(120) NOT NULL,
>
>In UserMapper.java I have the following method
>
>public interface UserMapper {
>   public long getUserId(String email);
>}
>
>In UserMapper.xml I have this:
>
><select id="getUserId" parameterType="string" resultType="long">
>SELECT id FROM users WHERE email = #{email}
></select>
>
>My DAO client code looks like this
>
>public long getUserId(String email) throws SQLException {
>         SqlSession session = sqlSessionFactory.openSession(true);
>         try {
>                 UserMapper mapper = session.getMapper(UserMapper.class);
>                 long userId = mapper.getUserId(email.toLowerCase());
>                 return userId;
>         } catch (SessionException sex) {
>                 throw new SQLException("No data found.", "02000");
>         } finally {
>                 session.close();
>         }
>}
>
>What I am unhappy about is that in order to 
>differentiate between the "no data found" 
>situation and other cases, I  would have to 
>check the SessionException for the string 
>"Expected one result to be returned by selectOne(), but found: 0".
>This is somehow unsatisfactory (at least to me) 
>since I do not like to trust that string to never change...
>
>Is there another way to deal with the situation 
>(without an additional SELECT COUNT...)? Maybe I 
>have not found the optimal way to solve the issue?
>Otherwise, I´d like either a specific exception 
>for this (and similar) cases, or a field with an 
>error code in SessionException.
>
>Thank you for any input on this,
>Thomas


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