On Wed, Aug 26, 2009 at 11:07 AM,= Rick <rickcr@gmai= l.com> wrote:

Maybe a bit of a hack but ...

public interface UserMapper {
=A0public List<Long> getUserIds(String email);
}

Keep the dao method the same...

public long getUserId(Strin= g email) {

but just do a quick check in there on the size of the Li= st returned, and do what you want with it (throw you own exception if over = size 1?)

and then just always return list.get(0)

On Wed, Aug 26, 2009 at 11:21 AM= , Thomas G. Schuessler <tgs@arasoft.de> wrote:

In my MySQL db, I have a table 'users' with (amongst others) these = fields:

=A0`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
=A0`email` varchar(120) NOT NULL,

In UserMapper.java I have the following method

public interface UserMapper {
=A0public long getUserId(String email);
}

In UserMapper.xml I have this:

<select id=3D"getUserId" parameterType=3D"string" re= sultType=3D"long">
SELECT id FROM users WHERE email =3D #{email}
</select>

My DAO client code looks like this

public long getUserId(String email) throws SQLException {
=A0 =A0 =A0 =A0SqlSession session =3D sqlSessionFactory.openSession(true);=
=A0 =A0 =A0 =A0try {
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0UserMapper mapper =3D session.getMapper(Use= rMapper.class);
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0long userId =3D mapper.getUserId(email.toLo= werCase());
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0return userId;
=A0 =A0 =A0 =A0} catch (SessionException sex) {
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0throw new SQLException("No data found.= ", "02000");
=A0 =A0 =A0 =A0} finally {
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0session.close();
=A0 =A0 =A0 =A0}
}

What I am unhappy about is that in order to differentiate between the "= ;no data found" situation and other cases, I =A0would have to check th= e 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 trus= t that string to never change...

Is there another way to deal with the situation (without an additional SELE= CT COUNT...)? Maybe I have not found the optimal way to solve the issue? Otherwise, I=B4d like either a specific exception for this (and similar) ca= ses, or a field with an error code in SessionException.

Thank you for any input on this,
Thomas

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Rick R